A Stable Ferryl Porphyrin at the Active Site of Y463M BthA

BthA is a diheme enzyme that is a member of the bacterial cytochrome c peroxidase superfamily, capable of generating a highly unusual Fe(IV)Fe(IV)=O oxidation state, known to be responsible for long-range oxidative chemistry in the enzyme MauG. Here we show that installing a canonical Met ligand in lieu of the Tyr found at the heme of MauG associated with electron transfer, results in a construct that yields an unusually stable Fe(IV)=O porphyrin at the peroxidatic heme. This state is spontaneously formed at ambient conditions using either molecular O(2) or H(2)O(2). The resulting data illustrate how a ferryl iron, with unforeseen stability, may be achieved in biology.