1,899 results match your criteria bonds ultrastructure

Biflavonoid-Induced Disruption of Hydrogen Bonds Leads to Amyloid-β Disaggregation.

Int J Mol Sci 2021 Mar 12;22(6). Epub 2021 Mar 12.

Department of Pharmacology, A.T. Still University, Kirksville, MO 63501, USA.

Deposition of amyloid β (Aβ) fibrils in the brain is a key pathologic hallmark of Alzheimer's disease. A class of polyphenolic biflavonoids is known to have anti-amyloidogenic effects by inhibiting aggregation of Aβ and promoting disaggregation of Aβ fibrils. In the present study, we further sought to investigate the structural basis of the Aβ disaggregating activity of biflavonoids and their interactions at the atomic level. Read More

View Article and Full-Text PDF

Water-Soluble Carbon Dots in Cigarette Mainstream Smoke: Their Properties and the Behavioural, Neuroendocrinological, and Neurotransmitter Changes They Induce in Mice.

Int J Nanomedicine 2021 16;16:2203-2217. Epub 2021 Mar 16.

Beijing Institute of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 100029, People's Republic of China.

Background: It is well known that smoking is harmful to health; however, it can also ameliorate anxiety. To date, it is unclear whether any nanoparticles found in cigarette mainstream smoke (CS) contribute to this effect.

Aim: The aim of this study was to assess the particle composition of CS to identify novel anti-anxiety components. Read More

View Article and Full-Text PDF

Tumour-Targeted and Redox-Responsive Mesoporous Silica Nanoparticles for Controlled Release of Doxorubicin and an siRNA Against Metastatic Breast Cancer.

Int J Nanomedicine 2021 8;16:1961-1976. Epub 2021 Mar 8.

Biobank, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, People's Republic of China.

Introduction: Metastatic breast cancer seriously harms women's health and is currently the tumour type with the highest mortality rate in women. Recently, the combinatorial therapeutic approaches that integrate anti-cancer drugs and genetic agents is an attractive and promising strategy for the treatment of metastatic breast cancer. Moreover, such a combination strategy requires better drug carriers that can effectively deliver the cargo to the breast cancer cells and achieve controlled release in the cells to achieve better therapeutic effects. Read More

View Article and Full-Text PDF

Antioxidant and Hepatoprotective Effects of Acidic-Hydrolysis Residue Polysaccharides from Shiitake Culinary-Medicinal Mushroom Lentinus edodes (Agaricomycetes) in Mice.

Int J Med Mushrooms 2021 ;23(2):85-96

College of Life Sciences, Shandong Agricultural University, Tai'an 271018, People's Republic of China.

The present work was designed to investigate the antioxidant and hepatoprotective effects of acidic-hydrolysis Lentinus edodes residue polysaccharides (Ac-LRP) on lipopolysaccharide-induced liver injury in mice. Hepatoprotective effects were observed in liver treated with Ac-LRP at doses of 200, 400, and 600 mg/kg body weight, respectively. Activities of superoxide dismutase, glutathione peroxide, catalase, total antioxidant capacity, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase and levels of total cholesterol, triglyceride, malondialdehyde, and lipid peroxidation in liver or serum samples were analyzed. Read More

View Article and Full-Text PDF
January 2021

Biochemical Characterization and Structural Insight into Interaction and Conformation Mechanisms of Lysine Decarboxylase (SmcadA).

Molecules 2021 Jan 29;26(3). Epub 2021 Jan 29.

The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 LiHu Boulevard, Wuxi 214122, China.

Inducible lysine decarboxylases (LDCs) are essential in various cellular processes of microorganisms and plants, especially under acid stress, which induces the expression of genes encoding LDCs. In this study, a novel LDC (SmcadA) was successfully expressed in , purified and characterized. The protein had an optimal pH of 6 and a temperature of 40 °C and phylogenetic analysis to determine the evolution of SmcadA, which revealed a close relation to sp. Read More

View Article and Full-Text PDF
January 2021

Structural analysis of rice Os4BGlu18 monolignol β-glucosidase.

PLoS One 2021 20;16(1):e0241325. Epub 2021 Jan 20.

School of Chemistry, Institute of Science and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Muang, Nakhon Ratchasima, Thailand.

Monolignol glucosides are storage forms of monolignols, which are polymerized to lignin to strengthen plant cell walls. The conversion of monolignol glucosides to monolignols is catalyzed by monolignol β-glucosidases. Rice Os4BGlu18 β-glucosidase catalyzes hydrolysis of the monolignol glucosides, coniferin, syringin, and p-coumaryl alcohol glucoside more efficiently than other natural substrates. Read More

View Article and Full-Text PDF

Crystal structure of steroid reductase SRD5A reveals conserved steroid reduction mechanism.

Nat Commun 2021 01 19;12(1):449. Epub 2021 Jan 19.

Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China.

Steroid hormones are essential in stress response, immune system regulation, and reproduction in mammals. Steroids with 3-oxo-Δ structure, such as testosterone or progesterone, are catalyzed by steroid 5α-reductases (SRD5As) to generate their corresponding 3-oxo-5α steroids, which are essential for multiple physiological and pathological processes. SRD5A2 is already a target of clinically relevant drugs. Read More

View Article and Full-Text PDF
January 2021

Heme-binding enables allosteric modulation in an ancient TIM-barrel glycosidase.

Nat Commun 2021 01 15;12(1):380. Epub 2021 Jan 15.

Departamento de Quimica Fisica. Facultad de Ciencias, Unidad de Excelencia de Quimica Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada, 18071, Granada, Spain.

Glycosidases are phylogenetically widely distributed enzymes that are crucial for the cleavage of glycosidic bonds. Here, we present the exceptional properties of a putative ancestor of bacterial and eukaryotic family-1 glycosidases. The ancestral protein shares the TIM-barrel fold with its modern descendants but displays large regions with greatly enhanced conformational flexibility. Read More

View Article and Full-Text PDF
January 2021

Myosin Binding Protein-C Forms Amyloid-Like Aggregates In Vitro.

Int J Mol Sci 2021 Jan 13;22(2). Epub 2021 Jan 13.

Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia.

This work investigated in vitro aggregation and amyloid properties of skeletal myosin binding protein-C (sMyBP-C) interacting in vivo with proteins of thick and thin filaments in the sarcomeric A-disc. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) found a rapid (5-10 min) formation of large (>2 μm) aggregates. sMyBP-C oligomers formed both at the initial 5-10 min and after 16 h of aggregation. Read More

View Article and Full-Text PDF
January 2021

Cellulose nanocrystalline hydrogel based on a choline chloride deep eutectic solvent as wearable strain sensor for human motion.

Carbohydr Polym 2021 Mar 7;255:117443. Epub 2020 Dec 7.

College of Energy, Xiamen University, Xiamen, 361102, China; Fujian Engineering and Research Center of Clean and High-valued Technologies for Biomass, Xiamen Key Laboratory of High-valued Utilization of Biomass, Xiamen University, Xiamen, 361102, China. Electronic address:

Owning to the viscoelastic properties, good biocompatibility and high strain sensitivity, choline chloride-based deep eutectic solvent (DES) hydrogels have been considered to be promising wearable strain sensors for human motion. However, traditional hydrogels are far away from the wearable strain sensor applications caused by their unsatisfied conductivity and weak mechanical properties. Herein, the strategy for functional ionic inorganic/organic interpenetrating (IPN) hydrogels preparation by cyclic freezing/thawing method was successfully developed. Read More

View Article and Full-Text PDF

Redox-responsive nanoparticles based on Chondroitin Sulfate and Docetaxel prodrug for tumor targeted delivery of Docetaxel.

Carbohydr Polym 2021 Mar 10;255:117393. Epub 2020 Nov 10.

Department of Pharmaceutics, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong Province, 250012, China. Electronic address:

In this paper, a novel redox-responsive nanoparticles has been designed for targeted delivery of docetaxel (DTX). Chondroitin sulfate (CS) was used to construct the nanoparticles due to the ability of tumor targeting through binding with CD44 receptor that overexpresses on the surfaces of various tumor cells. A redox-responsive small-molecular DTX prodrug was prepared through modifying with cystamine containing disulfide bonds (Cys-DTX). Read More

View Article and Full-Text PDF

Structural basis for nucleotide-independent regulation of acyl-CoA thioesterase from Bacillus cereus ATCC 14579.

Int J Biol Macromol 2021 Feb 28;170:390-396. Epub 2020 Dec 28.

School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea; KNU Institute for Microorganisms, Kyungpook National University, Daegu 41566, Republic of Korea. Electronic address:

Acyl-CoA thioesterase is an enzyme that catalyzes the cleavage of thioester bonds and regulates the cellular concentrations of CoASH, fatty acids, and acyl-CoA. In this study, we report the crystal structure of acyl-CoA thioesterase from Bacillus cereus ATCC 14579 (BcACT1) complexed with the CoA product. BcACT1 possesses a monomeric structure of a hotdog-fold and forms a hexamer via the trimerization of three dimers. Read More

View Article and Full-Text PDF
February 2021

Fast green FCF inhibits Aβ fibrillogenesis, disintegrates mature fibrils, reduces the cytotoxicity, and attenuates Aβ-induced cognitive impairment in mice.

Int J Biol Macromol 2021 Feb 19;170:33-41. Epub 2020 Dec 19.

State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology of Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin 300457, China. Electronic address:

Fast green FCF (FGF) is often used in foods, pharmaceuticals, and cosmetics. However, little is known about the interactions of FGF with amyloid-β protein (Aβ) associated with Alzheimer's disease. In this study, the inhibitory effects of FGF on Aβ fibrillogenesis, the disruption of preformed Aβ fibrils, the reduction of Aβ-induced cytotoxicity, and the attenuation of Aβ-induced learning and memory impairments in mice were investigated. Read More

View Article and Full-Text PDF
February 2021

Improvement of production yield and extraction efficacy of recombinant protein by high endosperm-specific expression along with simultaneous suppression of major seed storage proteins.

Plant Sci 2021 Jan 29;302:110692. Epub 2020 Sep 29.

PrevenTec inc. Ami-chuo 3-21-1, Inashiki, Ibaraki 300-0395, Japan.

Human transforming growth factor-β1 (hTGF-β1) was produced in transgenic rice seeds. To boost its production yield and to extract it simply, it was expressed under the control of seed-specific promoters along with the simultaneous suppression of endogenous seed storage proteins (SSPs) through RNA interference (RNAi). When driven by the 26 kDa α-globulin endosperm-specific promoter, it accumulated up to the markedly high level of 452 μg/grain. Read More

View Article and Full-Text PDF
January 2021

Molecular structure and interactions within amyloid-like fibrils formed by a low-complexity protein sequence from FUS.

Nat Commun 2020 11 12;11(1):5735. Epub 2020 Nov 12.

Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, 20892-0520, USA.

Protein domains without the usual distribution of amino acids, called low complexity (LC) domains, can be prone to self-assembly into amyloid-like fibrils. Self-assembly of LC domains that are nearly devoid of hydrophobic residues, such as the 214-residue LC domain of the RNA-binding protein FUS, is particularly intriguing from the biophysical perspective and is biomedically relevant due to its occurrence within neurons in amyotrophic lateral sclerosis, frontotemporal dementia, and other neurodegenerative diseases. We report a high-resolution molecular structural model for fibrils formed by the C-terminal half of the FUS LC domain (FUS-LC-C, residues 111-214), based on a density map with 2. Read More

View Article and Full-Text PDF
November 2020

The biology of corneal cross-linking derived from ultraviolet light and riboflavin.

Exp Eye Res 2021 01 7;202:108355. Epub 2020 Nov 7.

Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, USA; Cole Eye Institute, Cleveland Clinic, USA.

Over the past 20 years, corneal crosslinking (CXL) has been used by surgeons to halt progression in eyes with keratoconus. We reviewed the literature regarding the mechanism of action of CXL, the role of each of its components the strong biologic reaction, and their effects on cell interaction, proteins involved, wound healing, and cytotoxic reaction. CXL surgery involves a photochemical response in which ultraviolet light at a given wavelength and riboflavin participate. Read More

View Article and Full-Text PDF
January 2021

G-quadruplex-R-loop interactions and the mechanism of anticancer G-quadruplex binders.

Nucleic Acids Res 2020 12;48(21):11942-11957

Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126 Bologna, Italy.

Genomic DNA and cellular RNAs can form a variety of non-B secondary structures, including G-quadruplex (G4) and R-loops. G4s are constituted by stacked guanine tetrads held together by Hoogsteen hydrogen bonds and can form at key regulatory sites of eukaryote genomes and transcripts, including gene promoters, untranslated exon regions and telomeres. R-loops are 3-stranded structures wherein the two strands of a DNA duplex are melted and one of them is annealed to an RNA. Read More

View Article and Full-Text PDF
December 2020

Extracellular adsorption, intracellular accumulation and tolerance mechanisms of Cyclotella sp. to Cr(VI) stress.

Chemosphere 2021 May 17;270:128662. Epub 2020 Oct 17.

College of Safety and Environment Engineering, Shandong University of Science and Technology, Qingdao, 266510, China. Electronic address:

Heavy metals have caused widespread concern due to their adverse effects on aquatic organisms. However, there are few studies on their tolerance mechanism. In this study, the tolerance mechanisms of Cyclotella sp. Read More

View Article and Full-Text PDF

Adeno-Associated Virus (AAV-DJ)-Cryo-EM Structure at 1.56 Å Resolution.

Viruses 2020 10 20;12(10). Epub 2020 Oct 20.

Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.

Adeno-associated virus is the leading viral vector for gene therapy. AAV-DJ is a recombinant variant developed for tropism to the liver. The AAV-DJ structure has been determined to 1. Read More

View Article and Full-Text PDF
October 2020

The response surface methodology for optimization of tyrosinase immobilization onto electrospun polycaprolactone-chitosan fibers for use in bisphenol A removal.

Int J Biol Macromol 2020 Dec 18;165(Pt B):2049-2059. Epub 2020 Oct 18.

Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.

Composite polycaprolactone-chitosan material was produced by an electrospinning method and used as a support for immobilization of tyrosinase by mixed ionic interactions and hydrogen bonds formation. The morphology of the fibers and enzyme deposition were confirmed by SEM images. Further, multivariate polynomial regression was used to model the experimental data and to determine optimal conditions for immobilization process, which were found to be pH 7, temperature 25 °C and 16 h process duration. Read More

View Article and Full-Text PDF
December 2020

A nanoplatform based on mesoporous silica-coated gold nanorods for cancer triplex therapy.

J Mater Chem B 2020 11;8(42):9686-9696

Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China.

To enhance the efficacy of nanoparticle-based cancer therapy with reduced side effects and promote its clinical translation, a biocompatible nanocomposite based on mesoporous silica-coated gold nanorods (AuNR@MSN) for triple tumor therapy is reported in this study. The gold core served as a hyperthermia agent, while the MSN shell acted as a reservoir of chemotherapeutics owing to its excellent loading capacity. Cytochrome c with the apoptosis inducing function was anchored on the surface of AuNR@MSN to prevent drug leakage through redox-responsive disulfide bonds. Read More

View Article and Full-Text PDF
November 2020

Arginine-259 of UGT2B7 Confers UDP-Sugar Selectivity.

Mol Pharmacol 2020 12 2;98(6):710-718. Epub 2020 Oct 2.

Department of Clinical Pharmacology (P.C.N., N.C., J.O.M.) and Flinders Health and Medical Research Institute (FHMRI) Cancer Program (P.C.N., R.A.M., J.O.M.), Flinders Health and Medical Research Institute, Flinders University College of Medicine and Public Health, Flinders Medical Centre, South Australia, Australia.

Enzymes of the human UDP-glycosyltransferase (UGT) superfamily typically catalyze the covalent addition of the sugar moiety from a UDP-sugar cofactor to relatively low-molecular weight lipophilic compounds. Although UDP-glucuronic acid (UDP-GlcUA) is most commonly employed as the cofactor by UGT1 and UGT2 family enzymes, UGT2B7 and several other enzymes can use both UDP-GlcUA and UDP-glucose (UDP-Glc), leading to the formation of glucuronide and glucoside conjugates. An investigation of UGT2B7-catalyzed morphine glycosidation indicated that glucuronidation is the principal route of metabolism because the binding affinity of UDP-GlcUA is higher than that of UDP-Glc. Read More

View Article and Full-Text PDF
December 2020

Functional characterization of the ATPase-like activity displayed by a catalytic amyloid.

Biochim Biophys Acta Gen Subj 2021 01 9;1865(1):129729. Epub 2020 Sep 9.

Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Electronic address:

Background: Amyloids are highly ordered polypeptide aggregates stabilized by a beta-sheet structural core. Though classically associated to pathology, reports on novel functional roles of these proteins have increasingly emerged in the past decade. Moreover, the recent discovery that amyloids formed with rationally designed small peptides can exhibit catalytic reactivity has opened up new opportunities in both biology and biotechnology. Read More

View Article and Full-Text PDF
January 2021

Developing multicomponent edible films based on chitosan, hybrid of essential oils, and nanofibers: Study on physicochemical and antibacterial properties.

Int J Biol Macromol 2020 Dec 7;164:4065-4072. Epub 2020 Sep 7.

Department of Food science and Technology, Shahrood Branch, Islamic Azad University, Shahrood, Iran.

Plastic waste is one of the major threats to the environment, and an urgent need to replace synthetic plastics with sustainable materials is progressively growing. Herein, sustainable films based on chitosan, Satureja, and Thyme essential oils (EOs), and chitosan nanofibers (NF) were developed for the first time. To this end, 1% (w/w) of EOs and 2 wt% of NF were incorporated into the chitosan solution. Read More

View Article and Full-Text PDF
December 2020

NIR-responsive multi-healing HMPAM/dextran/AgNWs hydrogel sensor with recoverable mechanics and conductivity for human-machine interaction.

Carbohydr Polym 2020 Nov 25;247:116686. Epub 2020 Jun 25.

National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, Sichuan 610064, PR China. Electronic address:

Conductive and self-healing hydrogel sensor is perspective in human-machine interaction applications. However, the design of ideal self-healing hydrogels are always challenging. Herein, by introducing disulfide modified Ag nanowires (AgNWs), we show a novel self-healing hydrogel strain sensor with superior mechanics, conductivity, antibacterial property, and firstly realizing of self-healing with both recovery of mechanics and sensing properties. Read More

View Article and Full-Text PDF
November 2020

AgsA oligomer acts as a functional unit.

Biochem Biophys Res Commun 2020 09 28;530(1):22-28. Epub 2020 Jul 28.

Department of Biochemistry and Biophysics, The Health Science Center, Peking University, Beijing, 100191, China; Electron Microscopy Analysis Laboratory, Center of Medical and Health Analysis, Peking University, Beijing, 100191, China. Electronic address:

AgsA (aggregation-suppressing protein) is an ATP-independent molecular chaperone machine belonging to the family of small heat shock proteins (sHSP), and it can prevent the aggregation of non-natural proteins. However, the substrate-binding site of AgsA and the functional unit that captures and binds the substrate remain unknown. In this study, different N-terminal and C-terminal deletion mutants of AgsA were constructed and their effects on AgsA oligomer assembly and chaperone activity were investigated. Read More

View Article and Full-Text PDF
September 2020

CryoEM structure of the low-complexity domain of hnRNPA2 and its conversion to pathogenic amyloid.

Nat Commun 2020 08 14;11(1):4090. Epub 2020 Aug 14.

Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.

hnRNPA2 is a human ribonucleoprotein (RNP) involved in RNA metabolism. It forms fibrils both under cellular stress and in mutated form in neurodegenerative conditions. Previous work established that the C-terminal low-complexity domain (LCD) of hnRNPA2 fibrillizes under stress, and missense mutations in this domain are found in the disease multisystem proteinopathy (MSP). Read More

View Article and Full-Text PDF

Frequency and hydrogen bonding of nucleobase homopairs in small molecule crystals.

Nucleic Acids Res 2020 09;48(15):8302-8319

Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warszawa, Poland.

We used the high resolution and accuracy of the Cambridge Structural Database (CSD) to provide detailed information regarding base pairing interactions of selected nucleobases. We searched for base pairs in which nucleobases interact with each other through two or more hydrogen bonds and form more or less planar structures. The investigated compounds were either free forms or derivatives of adenine, guanine, hypoxanthine, thymine, uracil and cytosine. Read More

View Article and Full-Text PDF
September 2020

The effect of pre and post-ultrasonication on the aggregation structure and physicochemical characteristics of tapioca starch containing sucrose, isomalt and maltodextrin.

Int J Biol Macromol 2020 Nov 30;163:485-496. Epub 2020 Jun 30.

Department of Food Science and Technology, College of Agriculture, Fasa University, Fasa, Iran. Electronic address:

The present research investigated the aggregation behaviors of different levels (4, 8 and 12%) of incorporation of sucrose, isomalt and maltodextrin to pre or post- ultrasonication (400 W, 10 min at 60 °C) by fourier transform infrared spectroscopy (FTIR), microstructure by scanning electron microscopy (SEM), water absorption, pasting by rapid visco analysis (RVA), and thermal by differential scanning calorimetry (DSC). FTIR results showed that the aggregation process between polyol and starch after ultrasonication is more effective than before ultrasonication owning to more hydroxyl groups of polyols are engaged with the hydrogen bonds of starch which is more pronounced peaks at 1500-1750 cm, 1700-2700 cm and 3000-3700 cm. These findings are in line with the results from SEM analysis. Read More

View Article and Full-Text PDF
November 2020

Dynamic Covalent Chemistry Enables Reconfigurable All-Polysaccharide Nanogels.

Macromol Rapid Commun 2020 Aug 25;41(15):e2000213. Epub 2020 Jun 25.

Univ. Grenoble Alpes, (CERMAV)-CNRS, 601 rue de la Chimie, BP 53, Grenoble, Cedex 9 38041, France.

Dynamic covalent bonds are established upon molecular recognition of sugar derivatives by boronic acid molecules. These reversible links can be used in a cross-linking method to fabricate polymer-based responsive nanosystems. Herein, the design of the first dynamic nanogels made entirely of polysaccharides (PS) is reported. Read More

View Article and Full-Text PDF