Resonance Raman study on yeast cytochrome c peroxidase. Effect of coordination and axial ligands

Abstract

Resonance Raman spectra are reported for native ferric cytochrome c peroxidase, its cyanide and fluoride compounds, those of the ferrous enzyme and its cyanide and carbonyl compounds, and the spectrum of the hydrogen peroxide compound, compound I. Band frequencies of ferric horseradish peroxidase isoenzyme C2 and its derivatives are also given. Comparison of the frequencies of the bands around 1400, 1500, 1560-1580, and 1610-1640 cm-1 with those of other hemoproteins and heme model compounds showed that in ferric highspin compounds in particular the bands are not only spin and oxidation sensitive, as has previously been reported, but that they also reflect the coordination of the heme iron. It is suggested that ferric cytochrome c peroxidase and horseradish peroxidase are pentacoordinated. In the hexacoordinated fluoride, cyanide and carbon monoxide derivatives the bands reflect the spin state and the out-of-plane position of the heme iron. The spectrum of cytochrome c peroxidase compound I supports previous studies that suggest that it has a lowspin heme iron in the Fe(IV) oxidation state.