title: Oxygen exchange between the Fe(IV) = O heme and bulk water for the A2 isozyme of horseradish peroxidase.
abstract: Resonance Raman spectra were observed for compound II of horseradish peroxidase A2, and the Fe(IV) = O stretching Raman line was identified at 775 cm-1. This Raman line shifted to 741 cm-1 upon a change of solvent from H2(16)O to H2(18)O, indicating occurrence of the oxygen exchange between the Fe(IV) = O heme and bulk water. The oxygen exchange took place only at the acidic side of the heme-linked ionization with pKa = 6.9.
mesh_terms: D002384:Catalysis; D006418:Heme; D006735:Horseradish Peroxidase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron; D007527:Isoenzymes; D010100:Oxygen / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D013059:Spectrum Analysis, Raman; D014867:Water
chemical_list: D007527:Isoenzymes; D014867:Water; D006418:Heme; D007501:Iron; D006735:Horseradish Peroxidase; D010544:Peroxidases; D010100:Oxygen