Effect of alternative distal residues on the reactivity of cytochrome c peroxidase: Properties of CcP mutants H52D, H52E, H52N, and H52Q

► Four CcP mutants (H52D, H52E, H52Q, H52N) have been characterized. ► The mutants retain between 0.01 and 0.4% of the catalytic activity of CcP. ► The CcP(H52Q)-H2O2 reaction is the slowest yet observed for any CcP mutant. ► The endogenous decay of Compound I for the mutants is distinct from that of wtCcP. ► The rates of Compound I formation and HCN binding are correlated in 9 CcP mutants.