25 results match your criteria Australian Journal Of Chemistry[Journal]

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Determination of Sample Concentrations by PULCON NMR Spectroscopy.

Jeffrey Y W Mak

Aust J Chem 2022 16;75(2):160-164. Epub 2021 Nov 16.

Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.

PULCON (Pulse Length Based Concentration Determination) is a powerful, versatile, non-invasive, and accurate technique for measuring solution concentrations during routine NMR spectroscopy. As solutes are quantified directly by their unique resonances, this technique avoids weight-based errors caused by contaminants (e.g. Read More

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November 2021

A theoretical assessment of structure determination of multi-span membrane proteins by oriented sample solid-state NMR spectroscopy.

Aust J Chem 2020 20;73(3):246-251. Epub 2019 Sep 20.

Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.

Oriented sample solid state NMR (OS-ssNMR) spectroscopy allows direct determination of the structure and topology of membrane proteins reconstituted into aligned lipid bilayers. While OS-ssNMR theoretically has no upper size limit, its application to multi-span membrane proteins has not been established since most studies have been restricted to single or dual span proteins and peptides. Here, we present a critical assessment of the application of this method to multi-span membrane proteins. Read More

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September 2019

Efficient flow synthesis of human antimicrobial peptides.

Aust J Chem 2020 Apr 8;73(4):380-388. Epub 2020 Apr 8.

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.

Organisms from all kingdoms of life have evolved a vast array of peptidic natural products to defend against microbes. These are known collectively as antimicrobial peptides (AMPs) or host defense peptides, reflecting their abilities to not only directly kill microbes, but also to modulate host immune responses. Despite decades of investigation, AMPs have yet to live up to their promise as lead therapeutics, a reality that reflects, in part, our incomplete understanding of these diverse agents in their various physiological contexts. Read More

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On-resin strategy to label α-conotoxins: Cy5-RgIA, a potent α9α10 nicotinic acetylcholine receptor imaging probe.

Aust J Chem 2020 3;73(4):327-333. Epub 2019 Dec 3.

Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.

In-solution conjugation is the most commonly used strategy to label peptides and proteins with fluorophores. However, lack of site-specific control and high costs of fluorophores are recognised limitations of this approach. Here, we established facile access to grams of Cy5-COOH a two-step synthetic route, demonstrated that Cy5 is stable to HF treatment and therefore compatible with Boc-SPPS, and coupled Cy5 to the N-terminus of α-conotoxin RgIA while still attached to the resin. Read More

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December 2019

The Mechanism of Membrane Permeabilization by Peptides: Still an Enigma.

Aust J Chem 2019 11;73(3):96-103. Epub 2019 Nov 11.

Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD 21218.

Peptide-induced permeabilization of lipid vesicles has been measured for decades and has provided many insights into the sequence-structure-function relationships of membrane-active peptides. However, researchers in the field have noted that many experiments show transient permeabilization, in which a burst of leakage occurs immediately after peptide addition, followed by a slowdown or cessation of leakage before all contents have been released. This widely observed, but rarely studied, phenomenon is not explained by standard equilibrium pore models that are commonly invoked in both experimental and computational studies. Read More

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November 2019

Synthetic Models for Nickel-Iron Hydrogenase Featuring Redox-Active Ligands.

Aust J Chem 2017 May 11;70(5):505-515. Epub 2017 Jan 11.

Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Goodwin Ave., Urbana, IL 61801, USA.

The nickel-iron hydrogenase enzymes efficiently and reversibly interconvert protons, electrons, and dihydrogen. These redox proteins feature iron-sulfur clusters that relay electrons to and from their active sites. Reported here are synthetic models for nickel-iron hydrogenase featuring redox-active auxiliaries that mimic the iron-sulfur cofactors. Read More

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Total Solid-Phase Synthesis of Biologically Active Drosophila Insulin-Like Peptide 2 (DILP2).

Aust J Chem 2017 12;70(2):208-212. Epub 2016 Dec 12.

Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria 3010, Australia.

In the fruit fly , there are eight insulin-like peptides (DILPs) with DILPs 1-7 interacting with a sole insulin-like receptor tyrosine kinase (DInR) while DILP8 interacts with a single G protein-coupled receptor (GPCR), Lgr3. Loss-of-function mutation studies show that the neuropeptide DILP2 has a key role in carbohydrate and lipid metabolism as well as longevity and reproduction. A better understanding of the processes whereby DILP2 mediates its specific actions is required. Read More

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December 2016

Thienyl Difluoroboron β-Diketonates in Solution and Polylactide Media.

Aust J Chem 2016 7;69(5):537-545. Epub 2016 Mar 7.

Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22904.

Difluoroboron β-diketonates have impressive optical properties in both solution and the solid state. In particular, both fluorescence and room-temperature phosphorescence are present when the dyes are confined to a rigid matrix, such as poly(lactic acid) (PLA). To expand current knowledge and color range capabilities of this unique type of multi-emitting chromophore, a series of thienyl-substituted BFbdk complexes have been synthesized. Read More

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: Thinking outside "the box".

Aust J Chem 2015 Sep 28;68(9):1319-1328. Epub 2015 Aug 28.

Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA.

The logic of total synthesis transformed a stagnant state of medicinal and synthetic organic chemistry when there was a paucity of methods and reagents to synthesize drug molecules and/or natural products. Molecular imaging by positron emission tomography (PET) is now experiencing a renaissance in the way radiopharmaceuticals for molecular imaging are synthesized, however, a paradigm shift is desperately needed in the discovery pipeline to accelerate in vivo imaging studies. A significant challenge in radiochemistry is the limited choice of labeled reagents (or building blocks) available for the synthesis of novel radiopharmaceuticals with the most commonly used short-lived radionuclides carbon-11 (C; half-life ~20 minutes) and fluorine-18 (F; half-life ~2 hours). Read More

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September 2015

On the Mechanism of Berberine-INF55 (5-Nitro-2-phenylindole) Hybrid Antibacterials.

Aust J Chem 2015;67:1471-1480

School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.

Berberine-INF55 hybrids are a promising class of antibacterials that combine berberine and the NorA multidrug resistance pump inhibitor INF55 (5-nitro-2-phenylindole) together in one molecule via a chemically stable linkage. Previous studies demonstrated the potential of these compounds for countering efflux-mediated antibacterial drug resistance but they didn't establish whether the compounds function as originally intended, i.e. Read More

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January 2015

Photoinduced Cycloadditions in the Diversity-Oriented Synthesis Toolbox: Increasing Complexity with Straightforward Postphotochemical Modifications.

Aust J Chem 2015 24;68(11):1672-1681. Epub 2015 Jul 24.

Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208.

Rapid growth of complexity and unprecedented molecular architectures are realized via the excited-state intramolecular proton transfer (ESIPT) in -acylamidobenzaldehydes and ketones followed by [4+2] or [4+4] cycloadditions with subsequent postphotochemical modifications. The approach is congruent with Diversity-Oriented Synthesis: photoprecursors are synthesized in a modular fashion allowing for up to four diversity inputs. The complexity of the primary photoproducts is further enhanced using straightforward and high-yielding postphotochemical modification steps such as reactions with nitrile oxides, nitrones, Povarov reaction, and oxa-Diels-Alder reaction. Read More

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Molecular Characterization of Collagen Hydroxylysine -Glycosylation by Mass Spectrometry: Current Status.

Aust J Chem 2013 Jul;66(7):760-769

Mass Spectrometry Group, National Institutes of Health/National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, NC 27709, USA.

The most abundant proteins in vertebrates - the collagen family proteins - play structural and biological roles in the body. The predominant member, type I collagen, provides tissues and organs with structure and connectivity. This protein has several unique post-translational modifications that take place intra- and extra-cellularly. Read More

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Progress Towards Simple and Direct Detection of Adenylosuccinate Lyase Deficiency in Human Urine.

Aust J Chem 2011 Oct;64(11):1470-1473

Department of Chemistry, Portland State University, Portland, Oregon 97207, USA.

A rhodamine based boronic acid linearly responds to increasing 5-aminoimidazole-4-carboxamide riboside (AICAr) concentrations in human urine. This method is thus an advance in detecting adenylosuccinate lyase (ADSL) deficiency as AICAr is a model riboside for the ADSL substrates succinyladenosine (S-Ado) and succinylaminoimidazolecarboxamide riboside (SAICAr). ADSL deficiency is a rare but devastating disease of de novo purine synthesis in infants. Read More

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October 2011

N-Heterocyclic Carbene-Promoted Rauhut]Currier Reactions between Vinyl Sulfones and α,β-Unsaturated Aldehydes.

Aust J Chem 2011 Aug;64(8):1158-1164

Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Silverman Hall, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.

N-heterocyclic carbenes (NHCs) promote the addition of 1,1-bis(phenylsulfonyl)ethylene to the α-position of α,β-unsaturated aldehydes. The proposed reaction pathway for this Rauhut-Currier-type reaction includes an unusual conjugate addition of an NHC to a bis-vinyl sulfone. Read More

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Synthesis and Pharmacological Evaluation of 4-Iminothiazolidinones for Inhibition of PI3 Kinase.

Aust J Chem 2012 Jan;65(10):1396-1404

Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Vic. 3052, Australia.

The thiazolidinedione, compound , has previously shown pan-inhibition of the phosphoinositide 3-kinase (PI3K) class I isoforms. We hypothesized the derivatization of the thiazolidinedione core of compound could introduce isoform selectivity. We report the synthesis, characterization, and inhibitory activity of a novel series of 4-iminothiazolidin-2-ones for inhibition of the class I PI3K isoforms. Read More

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January 2012

Chemically Specific Imaging Through Stimulated Raman Photoexcitation and Ultrasound Detection: Minireview.

Aust J Chem 2012 Jan;65(3):260-265

Department of Physics, University of Wisconsin - Milwaukee, Milwaukee, WI 53211, USA. ; Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA.

A powerful combination of chemically specific Raman excitation and deep tissue ultrasound imaging holds the promise to attain spatially resolved distribution of chemical compounds inside the scattering medium. In this report, an attempt is made to evaluate the recent achievements and possible challenges with an eye on potential clinical applications. Read More

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January 2012

Photocatalytic Water Oxidation Using Manganese Compounds Immobilized in Nafion Polymer Membranes.

Aust J Chem 2011 Sep;64(9):1221-1228

Department of Chemistry, Yale University, New Haven, CT 06520, USA.

Robust water oxidation catalysts using earth abundant metals are required as part of an overall scheme to convert sunlight into fuels. Here, we report the immobilization of [[Formula: see text]O(5)(terpy)(4)(H(2)O)(2)](ClO(4))(6) (terpy = 2,2';6',2″-terpyridine), [Mn(4)O(6)(tacn)(4)](ClO(4))(4) (tacn = 1,4,7-triazacyclononane), and manganese dioxide nanoparticles in Nafion on fluorine-doped tin oxide conducting glass electrodes. The electrodes are illuminated with white light in the presence of an applied potential and the resulting photocurrent is assigned to the oxidation of solvent water. Read More

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September 2011

NHC-Based Self-Assembled Monolayers on Solid Gold Substrates.

Aust J Chem 2011 Aug;64(8):1177-1179

National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO), Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, Washington 98195, USA.

Thin films of 1,3-diethylbenzimidazol-2-ylidene (BIEt) were fabricated from THF solution on solid gold substrates and characterised by high-resolution X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. The surface-analytical data are in accord with the formation of self-assembled monolayers of BIEt molecules exhibiting an approximately vertical orientation on the substrate. The crystal structure of (BIEt)(2) was also determined. Read More

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Raman Spectroscopic Imaging of Cholesterol and Docosahexaenoic Acid Distribution in the Retinal Rod Outer Segment.

Aust J Chem 2011 May;64(5):611-616

Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46566.

Raman vibrational spectroscopic imaging was performed on retinal rod cells isolated from bullfrogs (Rana catesbeiana). The Raman spectra enable determination of the lipid and protein rich rod outer segment (ROS) from the nucleus and inner segment of the cell. Peak fitting analysis of spectra obtained from individual rod photoreceptor cells show characteristic vibrational modes that can be associated with cholesterol and docosahexaenoic acid containing lipids. Read More

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An Oxidized Abasic Lesion as an Intramolecular Source of DNA Adducts.

Aust J Chem 2011 Apr;64(4):438-442

Department of Chemistry, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA.

5'-(2-Phosphoryl-1,4-dioxobutane) (DOB) is a lesion produced in DNA via a variety of damaging agents. The DOB lesion spontaneously generates - and -but-2-en-1,4-dial () via β-elimination. - and -but-2-en-1,4-dial forms exocyclic adducts with nucleosides. Read More

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New Class of Hydroxy-Substituted Squaraine Rotaxane.

Aust J Chem 2010 ;63(5):792-796

Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46545, USA.

A templated macrocyclization reaction was used to permanently encapsulate a highly fluorescent hydroxy-substituted squaraine dye inside a tetralactam macrocycle. The free squaraine dye is quite rigid due to internal hydrogen bonding and its photophysical properties hardly change upon encapsulation. A combination of X-ray and NMR data show that the surrounding tetralactam macrocycle adopts an unusually rigid chair conformation and does not undergo rapid pirouetting. Read More

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January 2010

Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance[].

Aust J Chem 2009 Oct;62(10):1300-1307

Chemical Sciences Division, Lawrence Berkeley National Laboratories, 1 Cyclotron Road, Mail Stop 70A1150, Berkeley, CA, 94720.

The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV/visible and then efficiently transfer the energy to the lanthanoid center. The synthesis and the complexation of Ln(III) cations (Ln=Eu; Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)](-)) has been evaluated in terms of its thermodynamic stability, UV/visible absorption and luminescence properties. Read More

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October 2009

Saliniquinones A-F, New Members of the Highly Cytotoxic Anthraquinone-γ-Pyrones from the Marine Actinomycete

Aust J Chem 2010 Jun;63(6)

Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, CA 92093-0204, USA.

Six new anthraquinone-γ-pyrones, saliniquinones A-F (-), which are related to metabolites of the pluramycin/altromycin class, were isolated from a fermentation broth of the marine actinomycete (strain CNS-325). Their structures were determined by analysis of one- and two-dimensional NMR spectroscopic and high-resolution mass spectrometric data. The relative and absolute configurations of compounds - were determined by analysis of NOESY NMR spectroscopic data and by comparison of circular dichroism and optical rotation data with model compounds found in the literature. Read More

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Synthesis of Michael Acceptor Ionomers of Poly(4-Sulfonated Styrene-co-Poly(Ethylene Glycol) Methyl Ether Acrylate).

Aust J Chem 2009 Nov;62(11):1496-1500

Department of Chemistry and Biochemistry & California NanoSystems Institute, University of California, Los Angeles, 607 Charles E. Young Drive South, Los Angeles, California 90095-1569.

Ionomers containing sodium 4-styrene sulfonate (4SS) and poly(ethylene glycol) methyl ether acrylate (PEGA) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization was mediated by 1-phenylethyl dithiobenzoate chain transfer agent in a dimethylformamide/water solvent system. Well-defined copolymers of pPEGA-co-4SS were produced with molecular weights ranging from 10 kDa to 40 kDa and polydispersity indices (PDIs) of 1. Read More

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November 2009

Total Synthesis of (±)-Vibsanin E.

Aust J Chem 2009 ;62(9):980-982

School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072, Queensland, Australia.

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January 2009
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