title: Zinc-bound thiolate-disulfide exchange: a strategy for inhibiting metallo-beta-lactamases.
abstract: The mononuclear zinc thiolate complexes [(Tp(PhMe))Zn(S-R)], where Tp(PhMe) is hydrotris((3-methyl-5-phenyl)pyrazolyl)borate and (S-R) is benzyl thiolate, 4-nitrophenylthiolate, 4-trifluoromethylphenylthiolate, 4-chlorophenylthiolate, phenylthiolate, 2-methylphenylthiolate, 4-methylphenylthiolate, 4-methoxyphenylthiolate, or 4-hydroxyphenylthiolate, were synthesized. Representative members of the class were also characterized structurally. The benzyl thiolate complex undergoes a thiolate-disulfide exchange reaction with a variety of diphenyl and dipyridyl disulfides. Kinetic studies revealed that the reaction shows saturation behavior in both complex and disulfide for most of the disulfides studied. Combined with studies of the lability of the coordinated thiolate, a mechanism is proposed where the reactive species is the zinc-coordinated thiolate. When the free benzyl thiol was allowed to react with the same disulfides, the reaction was slower by a factor of 20-200 than that for the zinc-thiolate complex, depending on the particular disulfide employed. Since most metallo-beta-lactamases contain one or more cysteine residues, the one in the active site being coordinated to zinc, the present study was extended to examine whether disulfides can be used as inhibitors of these enzymes by selective oxidation of the metal-bound cysteine. Several disulfides allowed to react with metallo-beta-lactamase CcrA from Bacteroides fragilis were moderate to potent irreversible inhibitors of the enzyme.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Boerzel
authors.forename: Margery
authors.initials: M
authors.lastname: Koeckert
authors.forename: Weiming
authors.initials: W
authors.lastname: Bu
authors.forename: Bernhard
authors.initials: B
authors.lastname: Spingler
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D001426:Bacterial Proteins; D001441:Bacteroides fragilis / Q000201:enzymology*; D002384:Catalysis; D004220:Disulfides; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D004791:Enzyme Inhibitors; D008024:Ligands; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases; C063912:carbapenemase; D015032:Zinc