Apolar distal pocket mutants of yeast cytochrome c peroxidase: Hydrogen peroxide reactivity and cyanide binding of the TriAla, TriVal, and TriLeu variants

► CcP mutants with apolar heme pockets retain detectable catalytic activity. ► CcP mutants react with H2O2 104- to 107-times more slowly than wild-type CcP. ► Cyanide binding affinity is 103-fold less than wild-type CcP. ► Rates of the H2O2 and HCN reactions correlate over 7 orders of magnitude for 11 CcP mutants.