title: Mechanism-based inhibition of yeast alpha-glucosidase and human pancreatic alpha-amylase by a new class of inhibitors. 2-Deoxy-2,2-difluoro-alpha-glycosides.
abstract: 2-Deoxy-2,2-difluoroglycosides are a new class of mechanism-based inhibitors of alpha-glycosidases, which function via the accumulation of a stable difluoroglycosyl-enzyme intermediate. Two members of this new class of inhibitor have been synthesized and kinetic studies performed with their target glycosidases. Thus 2,4,6-trinitrophenyl 2-deoxy-2,2-difluoro-alpha-glucoside is shown to inactivate yeast alpha-glucosidase with a second order rate constant of ki/Ki = 0.25 min-1 mM-1. The equivalent difluoromaltoside inactivates human pancreatic alpha-amylase with ki/Ki = 0.0073 min-1 mM-1. Competitive inhibitors protect the enzyme against inactivation in each case, showing reaction to occur at the active site. A burst of release of one equivalent of trinitrophenolate observed upon inactivation of human pancreatic alpha-amylase proves the required 1:1 stoichiometry. These are the first mechanism-based inhibitors of this class to be described, and the first mechanism-based inhibitors of any sort for the medically important alpha-amylase. In addition to having potential as therapeutics, compounds of this class should prove useful in subsequent structural and mechanistic studies of these enzymes.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Braun
authors.forename: G D
authors.initials: GD
authors.lastname: Brayer
authors.forename: S G
authors.initials: SG
authors.lastname: Withers
mesh_terms: D002240:Carbohydrate Sequence; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000145:classification / Q000494:pharmacology*; D065089:Glycoside Hydrolase Inhibitors; D006027:Glycosides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010179:Pancreas / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D006027:Glycosides; D000516:alpha-Amylases