Publications by authors named "Cheng-Han Yang"

35 Publications

NOTCH1 mutations as prognostic marker in oral squamous cell carcinoma.

Pathol Res Pract 2021 Jul 10;223:153474. Epub 2021 May 10.

Department of Anatomic Pathology, Chang Gung Memorial Hospital at Keelung, Taiwan.

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity with poor prognosis. The dysregulation of Notch signaling pathway has been implicated in the OSCC tumorigenesis. However, the clinical implication of NOTCH1 mutation status in OSCC remains unelucidated. We extracted the NOTCH1 gene mutations from a whole exome sequencing dataset of 168 frozen OSCC tumor specimens and validated these NOTCH1 gene mutations by Sanger sequencing. We also assessed these NOTCH1 gene mutations and its pathological significance in our OSCC tumor tissues using immunohistochemistry. Univariate and multivariate analyses were also used to determine whether the association between NOTCH1 mutation status and prognostic factors was independent of other parameters. In this study, we have identified 44 (26.19 %) NOTCH1 gene mutations from a whole-exome sequencing of 168 OSCC formalin-fixed, paraffin-embedded (FFPE) tissue specimen. These mutations distributed in different NOTCH1 function domains, including the EGF-like repeats region, negative regulatory region, and Ankyrin repeats region. The immunohistochemical staining analysis revealed that NOTCH1 expression was increased in oral cancer tissues. In addition, of the 43 OSCC tumors with NOTCH1 mutations, we observed that the majority were negative for NOTCH1 intracellular domain 1 (NICD1) staining (76.74 %), and 10 tumors were positive for NICD1 staining (23.26 %). In conclusion, our study suggested that NOTCH1 expression is associated with the progression of OSCC. We also demonstrated that presence of a mutated NOTCH1 gene will help prognostic stratification in OSCC when combined with other clinicopathologic parameters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.prp.2021.153474DOI Listing
July 2021

The Fibronectin Expression Determines the Distinct Progressions of Malignant Gliomas via Transforming Growth Factor-Beta Pathway.

Int J Mol Sci 2021 Apr 6;22(7). Epub 2021 Apr 6.

Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.

Due to the increasing incidence of malignant gliomas, particularly glioblastoma multiforme (GBM), a simple and reliable GBM diagnosis is needed to screen early the death-threaten patients. This study aimed to identify a protein that can be used to discriminate GBM from low-grade astrocytoma and elucidate further that it has a functional role during malignant glioma progressions. To identify proteins that display low or no expression in low-grade astrocytoma but elevated levels in GBM, glycoprotein fibronectin (FN) was particularly examined according to the mining of the Human Protein Atlas. Web-based open megadata minings revealed that FN was mainly mutated in the cBio Cancer Genomic Portal but dominantly overexpressed in the ONCOMINE (a cancer microarray database and integrated data-mining platform) in distinct tumor types. Furthermore, numerous different cancer patients with high FN indeed exhibited a poor prognosis in the PrognoScan mining, indicating that FN involves in tumor malignancy. To investigate further the significance of FN expression in glioma progression, tumor specimens from five malignant gliomas with recurrences that received at least two surgeries were enrolled and examined. The immunohistochemical staining showed that FN expression indeed determined the distinct progressions of malignant gliomas. Furthermore, the expression of vimentin (VIM), a mesenchymal protein that is strongly expressed in malignant cancers, was similar to the FN pattern. Moreover, the level of epithelial-mesenchymal transition (EMT) inducer transforming growth factor-beta (TGF-β) was almost recapitulated with the FN expression. Together, this study identifies a protein FN that can be used to diagnose GBM from low-grade astrocytoma; moreover, its expression functionally determines the malignant glioma progressions via TGF-β-induced EMT pathway.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms22073782DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038731PMC
April 2021

Correction to: An anatomical perspective on clinicopathological characteristics and treatment outcomes of dorsal and ventrolateral tongue leukoplakia after carbon dioxide laser surgery.

BMC Oral Health 2021 Feb 15;21(1):70. Epub 2021 Feb 15.

Department of Otolaryngology Head and Neck Surgery, Chang Gung Memorial Hospital, Keelung. No. 222, Mai Chin Road, Keelung, 204, Taiwan, ROC.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12903-021-01430-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7885359PMC
February 2021

An anatomical perspective on clinicopathological characteristics and treatment outcomes of dorsal and ventrolateral tongue leukoplakia after carbon dioxide laser surgery.

BMC Oral Health 2021 01 28;21(1):45. Epub 2021 Jan 28.

Department of Otolaryngology Head and Neck Surgery, Chang Gung Memorial Hospital, Keelung. No. 222, Mai Chin Road, Keelung, 204, Taiwan, ROC.

Background: The tongue has been identified as a high-risk site for malignant transformation of oral leukoplakia. The purpose of this study was to investigate the clinicopathological characteristics and treatment outcomes of the dorsal and ventrolateral tongue leukoplakia.

Methods: Demographic data and pathological results of patients who underwent carbon dioxide laser surgery for tongue leukoplakia from 2002 to 2019 were retrospectively reviewed and analyzed statistically.

Results: Of the 111 patients enrolled, 80 were males and 31 females, with a mean age of 51.86 ± 11.84 years. The follow-up time was 3.74 ± 4.19 years. Fifteen patients had a postoperative recurrence (13.51%). Four (3.6%) patients developed malignant transformation. Annual transformation rate was 4.03%. There were no differences in the time to develop carcinoma (3.19 ± 1.94 vs. 3.51 ± 2.12 years, P = 0.83), overall cumulative malignant transformation rates (7.41% vs. 2.25%, P = 0.12), and annual transformation rates (2.32% vs. 0.64%, P = 0.099). The prevalence of the ventrolateral tongue leukoplakia was higher than that of the dorsal tongue leukoplakia (P < 0.001). The results of multivariate logistic regression analysis showed that the degree of pathology was the only independent prognostic factor related to postoperative malignant transformation (P = 0.045).

Conclusions: Dorsal tongue leukoplakia is not as frequently encountered clinically as ventrolateral tongue leukoplakia. The response of the dorsal tongue and ventrolateral tongue leukoplakia to laser therapy of are comparable in postoperative recurrence and postoperative malignant transformation. Clinicians should take a more aggressive attitude toward oral tongue leukoplakia with higher grade of dysplasia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12903-021-01403-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7844937PMC
January 2021

Identification of fidelity-governing factors in human recombinases DMC1 and RAD51 from cryo-EM structures.

Nat Commun 2021 01 14;12(1):115. Epub 2021 Jan 14.

Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.

Both high-fidelity and mismatch-tolerant recombination, catalyzed by RAD51 and DMC1 recombinases, respectively, are indispensable for genomic integrity. Here, we use cryo-EM, MD simulation and functional analysis to elucidate the structural basis for the mismatch tolerance of DMC1. Structural analysis of DMC1 presynaptic and postsynaptic complexes suggested that the lineage-specific Loop 1 Gln244 (Met243 in RAD51) may help stabilize DNA backbone, whereas Loop 2 Pro274 and Gly275 (Val273/Asp274 in RAD51) may provide an open "triplet gate" for mismatch tolerance. In support, DMC1-Q244M displayed marked increase in DNA dynamics, leading to unobservable DNA map. MD simulation showed highly dispersive mismatched DNA ensemble in RAD51 but well-converged DNA in DMC1 and RAD51-V273P/D274G. Replacing Loop 1 or Loop 2 residues in DMC1 with RAD51 counterparts enhanced DMC1 fidelity, while reciprocal mutations in RAD51 attenuated its fidelity. Our results show that three Loop 1/Loop 2 residues jointly enact contrasting fidelities of DNA recombinases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-20258-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809202PMC
January 2021

Oral tongue leukoplakia: analysis of clinicopathological characteristics, treatment outcomes, and factors related to recurrence and malignant transformation.

Clin Oral Investig 2021 Jun 7;25(6):4045-4058. Epub 2021 Jan 7.

Department of Otolaryngology-Head and Neck Surgery, Chang Gung Memorial Hospital, Keelung, No. 222, Mai Chin Road, Keelung, 204, Taiwan, Republic of China.

Objectives: The tongue is identified as a high-risk site for oral leukoplakia and malignant transformation. The purpose of this study is to investigate the clinicopathological characteristics and treatment outcomes of tongue leukoplakia and assess the factors related to recurrence and malignant transformation.

Materials And Methods: One hundred and forty-four patients who received carbon dioxide laser surgery for tongue leukoplakia from 2002 to 2019 were analyzed statistically.

Results: The follow-up period was 54.90 ± 54.41 months. Thirty patients showed postoperative recurrence (20.83%), and 12 patients developed malignant transformation (8.33%). The annual transformation rate was 2.28%. Univariate analysis showed that a history of head and neck cancer, size of lesion area, clinical appearance, and pathology were significant factors for both recurrence and malignant transformation. In the multivariate logistic regression, a history of head and neck cancer and size of lesion area were independent prognostic factors for recurrence, and a history of head and neck cancer was the only independent factor for postoperative malignant change.

Conclusions: Clinicians should adopt more aggressive strategies for tongue leukoplakia patients with a history of head and neck cancer.

Clinical Relevance: These results may help clinicians gain a better understanding of oral tongue leukoplakia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00784-020-03735-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8137631PMC
June 2021

Fibronectin in Cancer: Friend or Foe.

Cells 2019 12 20;9(1). Epub 2019 Dec 20.

The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.

The role of fibronectin (FN) in tumorigenesis and malignant progression has been highly controversial. Cancerous FN plays a tumor-suppressive role, whereas it is pro-metastatic and associated with poor prognosis. Interestingly, FN matrix deposited in the tumor microenvironments (TMEs) promotes tumor progression but is paradoxically related to a better prognosis. Here, we justify how FN impacts tumor transformation and subsequently metastatic progression. Next, we try to reconcile and rationalize the seemingly conflicting roles of FN in cancer and TMEs. Finally, we propose future perspectives for potential FN-based therapeutic strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells9010027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7016990PMC
December 2019

Surface-Initiated Initiators for Continuous Activator Regeneration (SI ICAR) ATRP of MMA from 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) Oxidized Cellulose Nanofibers for the Preparations of PMMA Nanocomposites.

Polymers (Basel) 2019 Oct 9;11(10). Epub 2019 Oct 9.

Department of Chemical Engineering, National Chung Hsing University, 145 Xingda Road, South District, Taichung 40227, Taiwan.

An effective method of oxidation from paper pulps via 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) compound to obtain TEMPO-oxidized cellulose nanofibers (TOCNs) was demonstrated. Following by acylation, TOCN having an atom transfer radical polymerization (ATRP) initiating site of bromoisobutyryl moiety (i.e., TOCN-Br) was successfully obtained. Through a facile and practical technique of surface-initiated initiators for continuous activator regeneration atom transfer radical polymerization (SI ICAR ATRP) of methyl methacrylate (MMA) from TOCN-Br, controllable grafting polymer chain lengths ( = ca. 10k-30k g/mol) with low polydispersity (PDI < 1.2) can be achieved to afford TOCN--Poly(methyl methacrylate) (PMMA) nanomaterials. These modifications were monitored by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), and water contact angle analysis. Eventually, TOCN--PMMA/PMMA composites were prepared using the solvent blending method. Compared to the pristine PMMA ( = 100 °C; tensile strength () = 17.1 MPa), the composites possessed high transparency with enhanced thermal properties and high tensile strength ( = 110 °C and = 37.2 MPa in 1 wt% TOCN containing case) that were investigated by ultraviolet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile tests. We demonstrated that minor amounts of TOCN--PMMA nanofillers can provide high efficacy in improving the mechanical and thermal properties of PMMA matrix.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym11101631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835816PMC
October 2019

Vaccinia viral A26 protein is a fusion suppressor of mature virus and triggers membrane fusion through conformational change at low pH.

PLoS Pathog 2019 06 20;15(6):e1007826. Epub 2019 Jun 20.

Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.

Vaccinia mature virus requires A26 envelope protein to mediate acid-dependent endocytosis into HeLa cells in which we hypothesized that A26 protein functions as an acid-sensitive membrane fusion suppressor. Here, we provide evidence showing that N-terminal domain (aa1-75) of A26 protein is an acid-sensitive region that regulates membrane fusion. Crystal structure of A26 protein revealed that His48 and His53 are in close contact with Lys47, Arg57, His314 and Arg312, suggesting that at low pH these His-cation pairs could initiate conformational changes through protonation of His48 and His53 and subsequent electrostatic repulsion. All the A26 mutant mature viruses that interrupted His-cation pair interactions of His48 and His 53 indeed have lost virion infectivity. Isolation of revertant viruses revealed that second site mutations caused frame shifts and premature termination of A26 protein such that reverent viruses regained cell entry through plasma membrane fusion. Together, we conclude that viral A26 protein functions as an acid-sensitive fusion suppressor during vaccinia mature virus endocytosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.ppat.1007826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6605681PMC
June 2019

The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues.

J Vis Exp 2018 06 16(136). Epub 2018 Jun 16.

The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University; Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University;

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 μM of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3791/56761DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6101755PMC
June 2018

Exceeding the theoretical fermentation yield in mixotrophic Rubisco-based engineered Escherichia coli.

Metab Eng 2018 05 26;47:445-452. Epub 2018 Apr 26.

Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan. Electronic address:

Rubisco-based engineered Escherichia coli MZLFB (E. coli BL21(DE3) Δzwf, Δldh, Δfrd) containing heterologous phosphoribulokinase (Prk) and Ribulose-1,5- bisphosphate carboxylase/oxygenase (Rubisco) was constructed for the mixotrophic growth. However, in situ CO recycling was hindered by clogs of pyruvate during glucose metabolism, which consequently resulted in an insufficient regeneration of NAD through the pflB-mediated ethanol production. Recombinant plasmid pLOI295 (encodes pyruvate decarboxylase and alcohol dehydrogenase II, referred to as the Pdc-based carbon tap valve (CTV) for convenience) was introduced into E. coli MZLFB + CTV to bypass the pflB-mediated ethanol production. Results show that while the C-2/C-1 ratio (i.e., the molar ratio of ethanol and acetate to formate and total CO) for parental strain MZLFB was 1.0 ± 0.1, the C-2/C-1 for MZLFB + CTV increased to 1.6 ± 0.1. This indicates that the Pdc-based CTV enhanced the performance of in situ CO recycling. By simultaneously utilizing glucose and CO, the fermentation product yield of MZLFB + CTV exceeded the normal theoretical yield and reached 2.2 ± 0.0 (mol/mol). In silico analysis shows that 61% of the glucose consumption went through the Rubisco-based engineered pathway when the CTV was equipped. Also shown are the average CO consumption rate of 55.3 mg L·h and an average ethanol production rate of 144.8 mg L·h. The conversion of CO to ethanol through the Rubisco-based engineered pathway and the Pdc-based carbon tap valve is important for mixotrophic growth, since these two modules serve as the energy sink to achieve intracellular energy balance. Also, during mixotrophic growth, ATP production from a certain percentage (39% in this study) of the EMP pathway activity is needed for mixotrophic growth.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ymben.2018.04.018DOI Listing
May 2018

Co-Expression of ORF with PHB Depolymerase (PhaZ ) in Escherichia coli Induces Efficient Whole-Cell Biodegradation of Polyesters.

Biotechnol J 2018 Apr 9;13(4):e1700560. Epub 2018 Feb 9.

Department of Chemical Engineering, National Chung Hsing University, Taichung, 402, Taiwan.

Whole-cell degradation of polyesters not only avoids the tedious process of enzyme separation, but also allows the degraded product to be reused as a carbon source. In this study, Escherichia coli BL21(DE3) harboring phaZ , a gene encoding poly(3-hydroxybutyrate) (PHB) depolymerase from Caldimonas manganoxidans, is constructed. The extra-cellular fraction of E. coli/pPHAZ exhibits a fast PHB degradation rate where it only took 35 h to completely degrade PHB films, while C. manganoxidans takes 81 h to do the same. The co-expression of ORF (a putative periplasmic substrate binding protein that is within the same operon of phaZ ) further improves the PHB degradation. While 28 h is needed for E. coli/pPHAZ to cause an 80% weight loss in PHB films, E. coli/pORFPHAZ needs only 21 h. Furthermore, it is able to degrade at-least four different polyesters, PHB, poly(lactic acid) (PLA), polycaprolactone (PCL), and poly(butylene succinate-co-adipate) (PBSA). Testing of the time course of 3-hydroxybutyrate concentration and the turbidity of the degradation solutions over time shows that PhaZ has both exo- and endo-enzymatic activity. The whole-cell E. coli/pORFPHAZ can be used for recycling various polyesters while ORF can potentially be a universal element for enhancing the secretion of recombinant protein.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/biot.201700560DOI Listing
April 2018

Homology Modeling and Molecular Dynamics Simulation Combined with X-ray Solution Scattering Defining Protein Structures of Thromboxane and Prostacyclin Synthases.

J Phys Chem B 2017 12 8;121(50):11229-11240. Epub 2017 Dec 8.

National Synchrotron Radiation Research Center , Hsinchu Science Park, Hsinchu 30076, Taiwan.

A combination of molecular dynamics (MD) simulations and X-ray scattering (SAXS) has emerged as the approach of choice for studying protein structures and dynamics in solution. This approach has potential applications for membrane proteins that neither are soluble nor form crystals easily. We explore the water-coupled dynamic structures of thromboxane synthase (TXAS) and prostacyclin synthase (PGIS) from scanning HPLC-SAXS measurements combined with MD ensemble analyses. Both proteins are heme-containing enzymes in the cytochrome P450 family, known as prostaglandin H (PGH) isomerase, with counter-functions in regulation of platelet aggregation. Currently, the X-ray crystallographic structures of PGIS are available, but those for TXAS are not. The use of homology modeling of the TXAS structure with ns-μs explicit water solvation MD simulations allows much more accurate estimation of the configuration space with loop motion and origin of the protein behaviors in solution. In contrast to the stability of the conserved PGIS structure in solution, the pronounced TXAS flexibility has been revealed to have unstructured loop regions in connection with the characteristic P450 structural elements. The MD-derived and experimental-solution SAXS results are in excellent agreement. The significant protein internal motions, whole-molecule structures, and potential problems with protein folding, crystallization, and functionality are examined.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jpcb.7b08299DOI Listing
December 2017

Pulmonary sclerosing pneumocytoma remains a diagnostic challenge using frozen sections: a clinicopathological analysis of 59 cases.

Histopathology 2018 Feb 28;72(3):500-508. Epub 2017 Nov 28.

Department of Pathology, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan.

Aims: Using intraoperative frozen sections to diagnose pulmonary sclerosing pneumocytoma is always challenging. However, an accurate diagnosis is needed to guide surgical management and prevent unnecessary treatment. The aim of this study was to investigate the most frequently misdiagnosed histological patterns and evaluate the potential diagnostic pitfalls of using frozen sections.

Methods And Results: We reviewed retrospectively 59 cases of sclerosing pneumocytoma that underwent an intraoperative frozen section examination. All original frozen section slides and permanent section slides were reviewed. The rate of accurate diagnosis using frozen sections was 44.1%, the deferral rate was 15.3% and 10 cases (16.9%) were misdiagnosed as malignancy. A solid-predominant pattern is misdiagnosed more frequently than other growth patterns. We also summarised the five major diagnostic pitfalls, including hypercellularity, glandular spaces, desmoplasia-like sclerosis, cellular atypia and coagulative necrosis.

Conclusions: In addition to evaluating the tumour circumscription and identifying the various growth patterns, we propose that the key to avoiding a misdiagnosis is to recognise the dual-cell populations in a tumour, i.e. cuboidal surface cells and stromal round cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/his.13391DOI Listing
February 2018

The comprehensive profile of fermentation products during in situ CO2 recycling by Rubisco-based engineered Escherichia coli.

Microb Cell Fact 2016 Aug 2;15(1):133. Epub 2016 Aug 2.

Department of Chemical Engineering, National Chung Hsing University, Taichung, 402, Taiwan.

Background: In our previous study, the feasibility of Rubisco-based engineered E. coli (that contains heterologous phosphoribulokinase (PrkA) and Rubisco) for in situ CO2 recycling during the fermentation of pentoses or hexoses was demonstrated. Nevertheless, it is perplexing to see that only roughly 70 % of the carbon fed to the bacterial culture could be accounted for in the standard metabolic products. This low carbon recovery during fermentation occurred even though CO2 emission was effectively reduced by Rubisco-based engineered pathway.

Results: In this study, the heterologous expression of form I Rubisco was found to enhance the accumulation of pyruvate in Escherichia coli MZLF [E. coli BL21(DE3) Δzwf, Δldh, Δfrd]. This may be attributed to the enhanced glycolytic reaction supported by the increased biomass and the ethanol/acetate ratio. Besides, it was found that the transcription of arcA (encodes the redox-dependent transcriptional activators ArcA that positively regulates the transcription of pyruvate formate-lyase) was down-regulated in the presence of Rubisco. The enhanced accumulation of pyruvate also occurs when PrkA is co-expressed with Rubisco in E. coli MZLF. Furthermore, E. coli containing Rubisco-based engineered pathway has a distinct profile of the fermentation products, indicating CO2 was converted into fermentation products. By analyzing the ratio of total C-2 (2-carbon fermentation products) to total C-1 (1-carbon fermentation product) of MZLFB (MZLF containing Rubisco-based engineered pathway), it is estimated that 9 % of carbon is directed into Rubisco-based engineered pathway.

Conclusions: Here, we report for the first time the complete profile of fermentation products using E. coli MZLF and its derived strains. It has been shown that the expression of Rubisco alone in MZLF enhances the accumulation of pyruvate. By including the contribution of pyruvate accumulation, the perplexing problem of low carbon recovery during fermentation by E. coli containing Rubisco-based engineered pathway has been solved. 9 % of glucose consumption is directed from glycolysis to Rubisco-based engineered pathway in MZLFB. The principle characteristics of mixotroph MZLFB are the high bacterial growth and the low CO2 emission.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12934-016-0530-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4971712PMC
August 2016

The In Situ Tryptophan Analogue Probes the Conformational Dynamics in Asparaginase Isozymes.

Biophys J 2016 04;110(8):1732-1743

Department of Chemistry and Center for Emerging Material and Advanced Devices, National Taiwan University, Taipei, Taiwan. Electronic address:

Dynamic water solvation is crucial to protein conformational reorganization and hence to protein structure and functionality. We report here the characterization of water dynamics on the L-asparaginase structural homology isozymes L-asparaginases I (AnsA) and II (AnsB), which are shown via fluorescence spectroscopy and dynamics in combination with molecular dynamics simulation to have distinct catalytic activity. By use of the tryptophan (Trp) analog probe 2,7-diaza-tryptophan ((2,7-aza)Trp), which exhibits unique water-catalyzed proton-transfer properties, AnsA and AnsB are shown to have drastically different local water environments surrounding the single Trp. In AnsA, (2,7-aza)Trp exhibits prominent green N(7)-H emission resulting from water-catalyzed excited-state proton transfer. In stark contrast, the N(7)-H emission is virtually absent in AnsB, which supports a water-accessible and a water-scant environment in the proximity of Trp for AnsA and AnsB, respectively. In addition, careful analysis of the emission spectra and corresponding relaxation dynamics, together with the results of molecular dynamics simulations, led us to propose two structural states associated with the rearrangement of the hydrogen-bond network in the vicinity of Trp for the two Ans. The water molecules revealed in the proximity of the Trp residue have semiquantitative correlation with the observed emission spectral variations of (2,7-aza)Trp between AnsA and AnsB. Titration of aspartate, a competitive inhibitor of Ans, revealed an increase in N(7)-H emission intensity in AnsA but no obvious spectral changes in AnsB. The changes in the emission profiles reflect the modulation of structural states by locally confined environment and trapped-water collective motions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bpj.2016.03.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4850355PMC
April 2016

The coupling of glycolysis and the Rubisco-based pathway through the non-oxidative pentose phosphate pathway to achieve low carbon dioxide emission fermentation.

Bioresour Technol 2015 25;187:189-197. Epub 2015 Mar 25.

Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan. Electronic address:

In this study, Rubisco-based engineered Escherichia coli, containing two heterologous enzymes of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoribulokinase (PrkA), has been shown to be capable of the in situ recycling of carbon dioxide (CO2) during glycolysis. Two alternative approaches have been proposed to further enhance the carbon flow from glycolysis to a Rubisco-based pathway through the non-oxidative pentose phosphate pathway (NOPPP). The first is achieved by elevating the expression of transketolase I (TktA) and the second by blocking the native oxidation-decarboxylation reaction of E. coli by deleting the zwf gene from the chromosome (designated as JB/pTA and MZB, respectively). Decreases in the CO2 yield and the CO2 evolution per unit mole of ethanol production by at least 81% and 40% are observed. It is demonstrated in this study that the production of one mole of ethanol using E. coli strain MZB, the upper limit of CO2 emission is 0.052mol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biortech.2015.03.090DOI Listing
January 2016

Sterically hindered luminescent Pt(II) -phosphite complexes for electroluminescent devices.

Chemistry 2015 Mar 20;21(13):5161-72. Epub 2015 Feb 20.

Westfälische Wilhelms-Universität Münster, Physikalisches Institut, Center for Nanotechnology (CeNTech), Heisenbergstr. 11, 48149 Münster (Germany).

Pt(II) complexes with one bulky, sterically demanding, tertiary phosphite ancillary ligand and a coordinating chromophore are herein presented. The phosphite ligand, tris(2,4-di-tert-butylphenyl) acts as a bidentate ligand coordinating the platinum ion through the central phosphorus atom and a cyclometalating carbon atom of one of the substituents. The two free phenoxy moieties lie above and below the coordination plane, leading to steric hindrance that avoids aggregation and provides solubility in organic solvents. The other two coordination sites on the central metal ion are occupied by a chromophoric ligand, which is responsible for the energy of the luminescent excited state. This separation of functions, on the two coordinated ligands, allows the use of a wider range of luminophores with good luminescent properties, maintaining the control of the intermolecular interactions with the non-chromophoric ligand. Based on this approach we were able to achieve a bright deep blue emission (λ=444 nm, Φem =0.38) from a complex with a tailored ligand, which was then used for the fabrication of an electroluminescent device. In addition commercially available luminophores were also employed to synthesize green emitters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.201405839DOI Listing
March 2015

Luminescent dinuclear Cu(I) complexes containing rigid tetraphosphine ligands.

Inorg Chem 2014 Oct 1;53(20):10944-51. Epub 2014 Oct 1.

Physikalisches Institut and CeNTech, University of Münster , Heisenbergstrasse 11, D-48149, Münster, Germany.

The synthesis and the photophysics of three dinuclear copper(I) complexes containing bis(bidentate)phosphine ligands are described. The steric constraint imposed by tetrakis(di(2-methoxyphenyl)phosphanyl)cyclobutane) (o-MeO-dppcb) in combination with 2,9-dimethyl-1,10-phenanthroline in one of the complexes leads to interesting photophysical properties. The compound shows an intense emission at room temperature in deoxygenated acetonitrile solution (Φ = 49%) and a long excited-state lifetime (13.8 μs). Interestingly, at low temperature, 77 K, the emission maximum shifts to lower energy, and the excited-state lifetime increases. This observation leads to the conclusion that a mixing between the excited triplet and singlet states is possible and that the degree of mixing and population of state strongly depends on temperature, as the energy difference is quite small. The electroluminescent properties of this compound were therefore tested in light-emitting electrochemical cells (LEECs), proving that the bright emission can also be obtained by electrically driven population of the singlet state.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic5012204DOI Listing
October 2014

Probing water environment of Trp59 in ribonuclease T1: insight of the structure-water network relationship.

J Phys Chem B 2015 Feb 28;119(6):2157-67. Epub 2014 Jul 28.

Department of Chemistry and Center for Emerging Material and Advanced Devices, National Taiwan University , Taipei 10617, Taiwan.

In this study, we used the tryptophan analogue, (2,7-aza)Trp, which exhibits water catalyzed proton transfer isomerization among N(1)-H, N(7)-H, and N(2)-H isomers, to probe the water environment of tryptophan-59 (Trp59) near the connecting loop region of ribonuclease Tl (RNase T1) by replacing the tryptophan with (2,7-aza)Trp. The resulting (2,7-aza)Trp59 triple emission bands and their associated relaxation dynamics, together with relevant data of 7-azatryptophan and molecular dynamics (MD) simulation, lead us to propose two Trp59 containing conformers in RNase T1, namely, the loop-close and loop-open forms. Water is rich in the loop-open form around the proximity of (2,7-aza)Trp59, which catalyzes (2,7-aza)Trp59 proton transfer in the excited state, giving both N(1)-H and N(7)-H isomer emissions. The existence of N(2)-H isomer in the loop-open form, supported by the MD simulation, is mainly due to the specific hydrogen bonding between N(2)-H proton and water molecule that bridges N(2)-H and the amide oxygen of Pro60, forming a strong network. The loop-close form is relatively tight in space, which squeezes water molecules out of the interface of α-helix and β2 strand, joined by the connecting loop region; accordingly, the water-scant environment leads to the sole existence of the N(1)-H isomer emission. MD simulation also points out that the Trp-water pairs appear to preferentially participate in a hydrogen bond network incorporating polar amino acid moieties on the protein surface and bulk waters, providing the structural dynamic features of the connecting loop region in RNase T1.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp503914sDOI Listing
February 2015

Efficient near-UV emitters based on cationic bis-pincer iridium(III) carbene complexes.

Inorg Chem 2013 Oct 9;52(19):10756-65. Epub 2013 Sep 9.

NRW Graduate School of Chemistry, University of Münster , D-48149 Münster, Germany.

We report on the photophysical studies of two cationic near-UV emitters based on bis-pincer Ir(III) carbene complexes: [Ir(nBu)(C(NHC)(Me)CC(NHC))2]X, where Ir(nBu)(C(NHC)(Me)CC(NHC)) is (4,6-dimethyl-1,3-phenylene-κC(2))bis(1-butylimidazol-2-ylidene) and X = I(-) or PF6(-)). The compounds are highly emitting in deaerated CH3CN solution with emission maxima at 384 and 406 nm, and photoluminescence quantum yields of 0.41 and 0.38, for [Ir(nBu)(C(NHC)(Me)CC(NHC))2]I and Ir(nBu)(C(NHC)(Me)CC(NHC))2]PF6, respectively. In order to gain deeper understandings into their structural and electronic features, as well as to ascertain the nature of the excited states involved into the electronic absorption processes, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been performed on the ground and excited states of the closely related complex [Ir(Me)(C(NHC)(Me)CC(NHC))2](+). In the solid state, an emission at low energy is observed (λ(max) = 500 nm) for both complexes. However, the intensity of the emission at high energy versus the intensity of the new emission at low energy is dependent on the nature of counterions. The origin of this emission is not completely clear, but the experimental data point to the formation of trapping sites induced by aggregation processes involving the interaction between the cationic emitter and the counterion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic302695qDOI Listing
October 2013

Phosphorescent organic light-emitting diodes with outstanding external quantum efficiency using dinuclear rhenium complexes as dopants.

Adv Mater 2012 Apr 19;24(15):2054-8. Epub 2012 Mar 19.

Physicaliches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms Universität Münster, Münster, Germany.

The photophysical and electroluminescence properties of two dinuclear rhenium(I) carbonyl complexes bearing 1,2-diazines are comprehensively investigated. The bromo-bridged complex is successfully used as triplet emitter for the preparation of vacuum-processed OLEDs with outstanding external quantum efficiencies, reaching a value of 10%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201104831DOI Listing
April 2012

Control of the mutual arrangement of cyclometalated ligands in cationic iridium(III) complexes. Synthesis, spectroscopy, and electroluminescence of the different isomers.

J Am Chem Soc 2011 Jul 16;133(27):10543-58. Epub 2011 Jun 16.

Physikalisches Institut, Mendelstrasse 7, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.

Synthetic control of the mutual arrangement of the cyclometalated ligands (C^N) in Ir(III) dimers, [Ir(C^N)(2)Cl](2), and cationic bis-cyclometalated Ir(III) complexes, [Ir(C^N)(2)(L^L)](+) (L^L = neutral ligand), is described for the first time. Using 1-benzyl-4-(2,4-difluorophenyl)-1H-1,2,3-triazole (HdfptrBz) as a cyclometalating ligand, two different Ir(III) dimers, [Ir(dfptrBz)(2)Cl](2), are synthesized depending on the reaction conditions. At 80 °C, the dimer with an unusual mutual cis-C,C and cis-N,N configuration of the C^N ligands is isolated. In contrast, at higher temperature (140 °C), the geometrical isomer with the common cis-C,C and trans-N,N arrangement of the C^N ligand is obtained. In both cases, an asymmetric bridge, formed by a chloro ligand and two adjacent nitrogens of the triazole ring of one of the cyclometalated ligands, is observed. The dimers are cleaved in coordinating solvents to give the solvento complexes [Ir(dfptrBz)(2)Cl(S)] (S = DMSO or acetonitrile), which maintain the C^N arrangement of the parent dimers. Controlling the C^N ligand arrangement in the dimers allows for the preparation of the first example of geometrical isomers of a cationic bis-cyclometalated Ir(III) complex. Thus, N,N-trans-[Ir(dfptrBz)(2)(dmbpy)](+) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine), with cis-C,C and trans-N,N arrangement of the C^N ligands, as well as N,N-cis-[Ir(dfptrBz)(2)(dmbpy)](+), with cis-C,C and cis-N,N C^N ligand orientation, are synthesized and characterized. Interestingly, both isomers show significantly different photophysical and electroluminescent properties, depending on the mutual arrangement of the C^N ligands. Furthermore, quantum chemical calculations give insight into the observed photophysical experimental data.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ja201691bDOI Listing
July 2011

Iridium metal complexes containing N-heterocyclic carbene ligands for blue-light-emitting electrochemical cells.

Inorg Chem 2010 Nov;49(21):9891-901

Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany.

A new series of cationic blue-emitting, heteroleptic iridium(III)-based metal complexes were systematically synthesized using two 4,6-difluorophenylpyridine ligands as well as one methyl- or n-butyl-substituted bisimidazolium salt carbene-type ligand. In degassed CH(2)Cl(2), all complexes display highly efficient, blue phosphorescence (λ(max) ∼ 452 nm; emission quantum yield ∼ 0.30) at room temperature and also show blue emission in a thin film. The measured photophysical properties of the complexes have been rationalized with the help of quantum-chemical calculations. Because of the high solubility of the complexes, solution-processed devices, light-emitting electrochemical cells (LEECs), were made. The results showed that true blue emission and short turn-on time is achieved when an ionic conductor, tetrabutylammonium trifluoromethanesulfonate, was used as the matrix for the film containing the emitters. These iridium complexes and the described devices are the bluest materials ever reported and the first case of LEECs based on carbene ligands.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic1009253DOI Listing
November 2010

Highly emissive metal-organic framework composites by host-guest chemistry.

Photochem Photobiol Sci 2010 Jun 17;9(6):846-53. Epub 2010 May 17.

Chair of Inorganic Chemistry II-Organometallics and Materials Chemistry, Ruhr-Universität Bochum, D-44870, Bochum, Germany.

The unique host-guest chemistry of metal-organic frameworks (MOFs) can be used to implement additional properties by loading the cavities with functional molecules or even nanoparticles. We describe the gas-phase loading of MOFs featuring either a three-dimensional (MOF-5, MOF-177 and UMCM-1) or one-dimensional channel system (MIL-53(Al)) with the highly emissive perylene derivative N,N-bis(2,6-dimethylphenyl)-3,4:9,10-perylene tetracarboxylic diimide (DXP) or an iridium complex, (2-carboxypyridyl)bis(3,5-difluoro-2-(2-pyridyl)phenyl)iridium(III) (FIrpic). The resulting host-guest composites show strong luminescence, with their optical properties being dominated by the guest species. DXP-loaded MOFs exhibit a high stability towards guest displacement by solvent molecules, while the interaction of FIrpic with the host is weaker. The emissive properties of intercalated DXP also indicate host-guest interactions such as caging effects, strong quenching of the MOF host emission, as well as aggregate formation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c0pp00070aDOI Listing
June 2010

Homoleptic tris(pyridyl pyrazolate) Ir(III) complexes: en route to highly efficient phosphorescent OLEDs.

Chemistry 2010 Apr;16(14):4315-27

Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan.

Treatment of the metal reagent IrCl(3)nH(2)O with two equivalents of 2-pyridyl pyrazole (N;N)H (3-tert-butyl-5-(2-pyridyl) pyrazole, (bppz)H and 3-trifluoromethyl-5-(2-pyridyl) pyrazole, (fppz)H), afforded the isomeric Ir(III) metal complexes with a general formula cis-[Ir(bppz)(2)Cl(2)]H (2 a), trans-[Ir(bppz)(2)Cl(2)]H (3 a), cis-[Ir(fppz)(2)Cl(2)]H (2 b), and trans-[Ir(fppz)(2)Cl(2)]H (3 b). Single-crystal X-ray diffraction studies on 2 b and 3 a revealed the coexistence of two pyrazolate chelates and two terminal chloride ligands on the coordination sphere. Subsequent reactivity studies confirmed their intermediacy to the preparation of homoleptic mer-[Ir(bppz)(3)] (1 a) and mer-[Ir(fppz)(3)] (1 b) that showed dual intraligand and ligand-to-ligand charge-transfer phosphorescence at room temperature. To attain bright, room-temperature phosphorescence further, we then synthesized two isoquinolinyl pyrazolate complexes, mer-[Ir(bipz)(3)] (4 a) and mer-[Ir(fipz)(3)] (4 b) ((bipz)H=3-tert-butyl-5-(1-isoquinolyl) pyrazole and (fipz)H=3-trifluoromethyl-5-(1-isoquinolyl) pyrazole). Their orange luminescence is mainly attributed to the mixed MLCT/pipi* transition, and the quantum yields were as high as 86 (4 a) and 50 % (4 b) in degassed CH(2)Cl(2) solution at RT. The organic light-emitting diodes (OLEDs) were then fabricated by using 4 a as a dopant, giving orange luminescence with CIE(x,y)=0.55, 0.45 (CIE(x,y)=the 1931 Commission Internationale de L'Eclairage (x,y) coordinates) and peak efficiencies of 14.6 % photon/electron, 34.8 cd A(-1), 26.1 lm W(-1). The device data were then compared with the previously reported heteroleptic complex [Ir(dfpz)(2)(bipz)] (5) ((dfpz)H=1-(2,4-difluorophenyl) pyrazole), revealing the possible effect of the bipz chelate and phosphor design on the overall electrophosphorescent performance, which can be understood by the differences in the carrier-transport properties.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.200902902DOI Listing
April 2010

Color tuning associated with heteroleptic cyclometalated Ir(III) complexes: influence of the ancillary ligand.

Dalton Trans 2007 May(19):1881-90

Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan.

We report the preparation of a series of new heteroleptic Ir(III) metal complexes chelated by two cyclometalated 1-(2,4-difluorophenyl)pyrazole ligands (dfpz)H and a third ancillary bidentate ligand (L=X). Such an intricate design lies in a core concept that the cyclometalated dfpz ligands always warrant a greater pi pi* gap in these series of iridium complexes. Accordingly, the lowest one-electron excitation would accommodate the pi* orbital of the ancillary L=X ligands, the functionalization of which is then exploited to fine-tune the phosphorescent emission wavelengths. Amongst the L=X ligands designed, three classes (series 1-3) can be categorized, and remarkable bathochromic shifts of phosphorescence were observed by (i) replacing the 2-benzoxazol-2-yl substituent (1a) with the 2-benzothiazol-2-yl group (1b) in the phenolate complexes, (ii) converting the pyridyl group (2a) to the pyrazolyl group (2b) and even to the isoquinolyl group (2c) in the pyrazolate complexes and (iii) extending the pi-conjugation of the benzimidazolate ligand from 3a to 3b. Single-crystal X-ray diffraction study on complex [(dfpz)Ir(bzpz)] (2b) was conducted to confirm their general molecular architectures. Complex 2b was also used as a representative example for fabrication of multilayered, green-emitting phosphorescent OLEDs using the direct thermal evaporation technique.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b700998dDOI Listing
May 2007

Iridium(I) pyridyl azolate complexes with saturated red metal-to-ligand charge transfer phosphorescence; fundamental and potential applications in organic light-emitting diodes.

Chemistry 2007 ;13(9):2686-94

Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan.

Preparation of a new series of neutral metal complexes [(cod)Ir(fppz)] (1), [(cod)Ir(bppz)] (2), [(cod)Ir(fptz)] (3) and [(cod)Ir(bptz)] (4), bearing one cod ligand and a pyridyl azolate chelate are reported. A single-crystal X-ray diffraction study of 3 reveals the expected distorted square-planar geometry. The lowest absorption band consists of IrI atom increased triplet dpi-->pi* transitions (3MLCT), the assignment of which is firmly supported by the theoretical approaches. Complexes 1-4 exhibit weak phosphorescence in degassed solution at room temperature, whereas much more intense, solid-state phosphorescence appears in the range 622-649 nm. The pure MLCT emission was used as a prototypical model to address its remarkable spectral differences from the IrIII isoquinoline pyrrolide complex (5), which has mainly 3pipi phosphorescence. Complex 3 was used as a dopant to fabricate red-emitting phosphorescent organic light-emitting diodes (OLEDs). For the 7 % doped device, a maximum brightness of 3010 cd m-2 was achieved at an applied voltage of 15 V and with CIE coordinates of (0.56, 0.33), demonstrating for the first time the potential of neutral IrI complexes in OLED applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.200601019DOI Listing
June 2007

A new family of homoleptic Ir(III) complexes: tris-pyridyl azolate derivatives with dual phosphorescence.

Chemphyschem 2006 Nov;7(11):2294-7

Department of Chemistry and Instrumentation Center, National Taiwan University, Taipei 106, Taiwan.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cphc.200600461DOI Listing
November 2006
-->