Inhibition by active site directed covalent modification of human glyoxalase I

Mechanism-Based Studies of the Active Site-Directed Inhibition and Activation of Enzyme Transketolase

Derivatives of phenyl-keto butenoic acids have been reported to be inhibitors of pyruvate decarboxylase, (PDC). The inhibition of transketolase, a thiamine requiring enzyme such as PDF, by meta nitrophenyl derivative of 2-oxo-3-butenoic acid (MNPB) is reported here. These studies indicate that the inhibitor binds to the enzyme at the active site. A two-step inhibition was observed, first th...

Site-Directed Covalent Immobilization

Covalent modification of reduced flavin mononucleotide in type-2 isopentenyl diphosphate isomerase by active-site-directed inhibitors.

Evidence for an unusual catalysis of protonation/deprotonation by a reduced flavin mononucleotide cofactor is presented for type-2 isopentenyl diphosphate isomerase (IDI-2), which catalyzes isomerization of the two fundamental building blocks of isoprenoid biosynthesis, isopentenyl diphosphate and dimethylallyl diphosphate. The covalent adducts formed between irreversible mechanism-based inhibi...

Human apolipoprotein A-I. Post-translational modification by covalent phosphorylation.

In vitro phosphorylation of purified human plasma apolipoprotein A-I (apoA-I) by a recently characterized Ca2+/calmodulin-dependent kinase (Beg, Z. H., Stonik, J. A., and Brewer, H. B., Jr. (1987) J. Biol. Chem. 262, 13228-13240) was time-, Ca2+-, and calmodulin-dependent. Maximal phosphorylation of human apoA-I revealed a stoichiometry of approximately 1 mol of PO4/mol of apoA-I. Phosphorylati...

1-Bromopinacolone, an active site-directed covalent inhibitor for acetylcholinesterase.

1-Bromopinacolone, BrPin, acts initially as a reversible competitive inhibitor for acetylcholinesterase, KI = 0.18 mM in hydrolysis of acetylcholine. Unlike bromoacetone, with time it acts as an irreversible covalent inhibitor. BrPin has a hydrolytic half-life of 30 h at the pH of incubation, 7.8. The enzyme-BrPin complex is 50% inactivated in 2 h. First order kinetics are observed; the rate co...