Dissecting peroxiredoxin catalysis: separating binding, peroxidation, and resolution for a bacterial AhpC.

摘要: Peroxiredoxins make up a ubiquitous family of cysteine-dependent peroxidases that reduce hydroperoxide or peroxynitrite substrates through formation cysteine sulfenic acid (R-SOH) at the active site. In 2-Cys peroxiredoxins, second (resolving) reacts with to form disulfide bond. For all structural rearrangements in vicinity site cysteine(s) are necessary allow bond and subsequent reductive recycling. this study, we evaluated rate constants for individual steps catalytic cycle Salmonella typhimurium AhpC. Conserved Trp residues situated close both peroxidatic resolving cysteines AhpC give rise large changes fluorescence during cycle. recycling, AhpF very efficiently reduces disulfide, single discernible step constant 2.3 × 107 M–1 s–1. Peroxide reduction was more complex could be modeled as three steps, beginning reversi...