Differential Kinetics of Two-Cysteine Peroxiredoxin Disulfide Formation Reveal a Novel Model for Peroxide Sensing.

ABSTRACT: Two-cysteine peroxiredoxins (Prx) have a three-step catalytic cycle consisting of (1) reduction of peroxide and formation of sulfenic acid on the enzyme, (2) condensation of the sulfenic acid with a thiol to form disulfide, also known as resolution, and (3) reduction of the disulfide by a reductant protein. By following changes in protein fluorescence, we have studied the pH dependence of reaction 2 in human peroxiredoxins 1, 2, and 5 and in Salmonella typhimurium AhpC and obtained rate constants for the reaction and p K_a values of the thiol and sulfenic acid involved for each system. The observed reaction 2 rate constant spans 2 orders of magnitude, but in all cases, reaction 2 appears to be slow compared to the same reaction in small-molecule systems, making clear the rates ar

SUBMITTER: Portillo-Ledesma S 

PROVIDER: S-EPMC6383210 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature