A5031683170- Carbohydrate Chemistry and Synthesis
- Microbial Natural Products and Biosynthesis
- Enzyme Production and Characterization
- Glycosylation and Glycoproteins Research
- Pesticide and Herbicide Environmental Studies
- Enzyme Catalysis and Immobilization
- Biochemical and Molecular Research
- Metalloenzymes and iron-sulfur proteins
- Natural Antidiabetic Agents Studies
- Metal-Catalyzed Oxygenation Mechanisms
- Seaweed-derived Bioactive Compounds
- HIV/AIDS drug development and treatment
- Genomics and Phylogenetic Studies
- Microbial Metabolites in Food Biotechnology
- Legume Nitrogen Fixing Symbiosis
- Enzyme Structure and Function
- Biochemical and Structural Characterization
- Synthetic Organic Chemistry Methods
- Metal complexes synthesis and properties
- DNA and Nucleic Acid Chemistry
- Porphyrin Metabolism and Disorders
- Metabolism and Genetic Disorders
- Marine Sponges and Natural Products
- RNA and protein synthesis mechanisms
- Chemical Synthesis and Characterization
Queens University
2015-2025
Queen's University
2015-2024
Bridge University
2024
University of Richmond
2024
Chemnitz University of Technology
2008
University of York
2002-2007
The University of Western Australia
2003-2007
ETH Zurich
2007
University of Zurich
2003-2004
University of British Columbia
1998-2003
In order to accelerate the hydrolysis of glycosidic bonds by factors approaching 10(17)-fold, glycosidases have evolved finely tuned active sites optimally configured for transition-state stabilization. Structural analyses various enzyme complexes representing stable intermediates along reaction coordinate, in conjunction with detailed mechanistic studies on wild-type and mutant enzymes, delineated contributions nucleophilic general acid/base catalysis, as well roles noncovalent...
Abstract Bacterial natural products are a diverse and valuable group of small molecules, genome sequencing indicates that the vast majority remain undiscovered. The prediction product structures from biosynthetic assembly lines can facilitate their discovery, but highly automated, accurate, integrated systems required to mine broad spectrum sequenced bacterial genomes. Here we present genome-guided discovery tool automatically predict, combinatorialize identify polyketides nonribosomal...
The design and synthesis of transition-state mimics reflects the growing need both to understand enzymatic catalysis influence strategies for therapeutic intervention. Iminosugars are among most potent inhibitors glycosidases. Here, binding 1-deoxynojirimycin (+)-isofagomine "family GH-1" beta-glucosidase Thermotoga maritima is investigated by kinetic analysis, isothermal titration calorimetry, X-ray crystallography. these iminosugar driven a large favorable enthalpy. greater inhibitory...
The inhibition of glycoside hydrolases, through transition-state mimicry, is important both as a probe enzyme mechanism and in the continuing quest for new drugs, notably treatment cancer, HIV, influenza, diabetes. high affinity with which these enzymes are known to bind transition state provides framework upon design potent inhibitors. Recent work [for example, Bülow, A. et al. J. Am. Chem. Soc. 2000, 122, 8567-8568; Zechel, D. L. 2003, 125, 14313-14323] has revealed quite confusing...
The conformational reaction pathway for β-mannosidases proposed here is distinct from that of glucosidases and cellulases. proposal based on substrate distortions along the a β-mannosidase (see picture) were revealed by X-ray crystallography are close in space to known inhibitors.
The mechanism by which polysaccharide-hydrolyzing enzymes manifest specificity toward heterogeneous substrates, in the sequence of sugars is variable, unclear. An excellent example such heterogeneity provided plant structural polysaccharide glucomannan, comprises a backbone beta-1,4-linked glucose and mannose units. beta-Mannanases, located glycoside hydrolase (GH) families 5 26, hydrolyze glucomannan cleaving glycosidic bond mannosides at -1 subsite. these select for or distal subsites,...
The sequential activities of PhnY, an α-ketoglutarate/Fe(II)-dependent dioxygenase, and PhnZ, a Fe(II)-dependent enzyme the histidine-aspartate motif hydrolase family, cleave carbon-phosphorus bond organophosphonate natural product 2-aminoethylphosphonic acid. PhnY adds hydroxyl group to α-carbon, yielding 2-amino-1-hydroxyethylphosphonic acid, which is oxidatively converted by PhnZ inorganic phosphate glycine. reaction represents new mechanism for metabolic cleavage bond.
Glycosynthases are nucleophile mutants of retaining glycosidases that catalyze the glycosylation sugar acceptors using glycosyl fluoride donors, thereby synthesizing oligosaccharides. The ‘original’ glycosynthase, derived from Agrobacterium sp. β‐glucosidase (Abg) by mutating glutamate to alanine (E358A), synthesizes oligosaccharides in yields exceeding 90% [Mackenzie, L.F., Wang, Q., Warren, R.A.J. and Withers, S.G. (1998) J. Am. Chem. Soc. 120, 5583–5584]. This mutant has now been...
For the first time, new technique of time-resolved electrospray ionization mass spectrometry (ESI-MS) has been used to accurately measure pre-steady state kinetics an enzymatic reaction by monitoring a transient enzyme intermediate. The illustrate this approach, Bacillus circulans xylanase, is retaining glycosidase that hydrolyzes xylan or beta-xylobiosides through double-displacement mechanism involving covalent xylobiosyl-enzyme A low steady level intermediate formed during hydrolysis...
Engineering enzymes: The glutamic acid nucleophile of a retaining β-mannosidase has been replaced with serine residue to form β-mannosynthase. When the new enzyme is provided an α-mannosyl fluoride donor and appropriate acceptor, β-mannoside linkages are synthesized (see scheme). Remarkably, can be generated in situ by providing mannosynthase excess ion. Supporting information for this article available on WWW under http://www.angewandte.com or from author. Please note: publisher not...
Organophosphonate utilization by Escherichia coli requires the 14 cistrons of phnCDEFGHIJKLMNOP operon, which carbon-phosphorus lyase has been postulated to consist seven polypeptides specified phnG phnM. A 5,660-bp DNA fragment encompassing phnGHIJKLM is cloned, followed expression in E. and purification Phn-polypeptides. PhnG, PhnH, PhnI, PhnJ, PhnK copurify as a protein complex ion-exchange, size-exclusion, affinity chromatography. The five also comigrate native-PAGE. Cross-linking...
Abstract Nucleocidin is one of the very few natural products known to contain fluorine. Mysteriously, nucleocidin producer Streptomyces calvus ATCC 13382 has not been observed synthesize compound since its discovery in 1956. Here, we report that complementation S. with a functional bldA ‐encoded Leu‐tRNA UUA molecule restores production nucleocidin. was detected culture extracts by 19 F NMR spectroscopy, HPLC‐ESI‐MS, and HPLC‐continuum source molecular absorption spectroscopy for...
The silicon-bridged [1]ferrocenophanes Fe(η-C5H4)2SiRR' [3 (R = Me, R' Cl), 4 Cl)] with chlorine substituent(s) at silicon were prepared via the reaction of Fe(η-C5H4Li)2·TMEDA (TMEDA tetramethylethylenediamine) chlorinated silanes MeSiCl3 and SiCl4, respectively. An X-ray diffraction study indicated that cyclopentadienyl rings in this species are tilted by an angle 19.2(4)°, typical other structurally characterized [1]ferrocenophanes. Thermal ring-opening polymerization (ROP) 3 250 °C...
Glycosidases are some of the most ubiquitous enzyme in nature. Their biological significance, coupled to their enormous catalytic prowess derived from tight binding transition state, is reflected importance as therapeutic targets. Many glycosidase inhibitors known. Imino sugars often potent inhibitors, yet many facets mode action, such degree, if any, transition-state "mimicry" and protonation state when bound target remain unclear. Atomic resolution analysis endoglucanase, Cel5A, complex...
In Escherichia coli, internalization and catabolism of organophosphonicacids are governed by the 14-cistron phnCDEFGHIJKLMNOP operon. The phnP gene product was previously shown to encode a phosphodiesterase with unusual specificity toward ribonucleoside 2′,3′-cyclic phosphates. Furthermore, displays shared synteny phnN across bacterial phn operons. Here role PhnP examined 31P NMR spectrometry on culture supernatants E. coliphn mutants grown in presence alkylphosphonic acid or phosphite....
The enzymes PhnY and PhnZ comprise an oxidative catabolic pathway that enables marine bacteria to use 2-aminoethylphosphonic acid as a source of inorganic phosphate. is notable for catalyzing the cleavage carbon-phosphorus bond using Fe(II) dioxygen, despite belonging large family hydrolytic enzymes, HD-phosphohydrolase superfamily. We have determined high-resolution structures bound its substrate, (R)-2-amino-1-hydroxyethylphosphonate (2.1 Å), buffer additive, l-tartrate (1.7 Å). reveal...
Potato is prone to many drastic diseases like potato common scab (CS). As no highly effective methods exist for managing CS, this study explored the possibility of using biological control. Ten bacterial strains were isolated from CS-infected tubers four different locations Punjab, Pakistan, and identified based on biochemical molecular analysis. Analysis 16s rDNA sequences amplified by PCR revealed be Streptomyces scabies, S. turgidiscabies stelliscabiei. Pathogenic islands also confirmed...