Cytochrome P450 plays a central role in drug metabolism and steroid biosynthesis. Among heme enzymes, cytochrome P450 and NO synthase (NOS) have strong oxidizing ability and unusual structure, in that their heme iron has thiolate coordination. We previously succeeded in synthesizing the first synthetic heme thiolate (SR complex)¹ which retains thiolate coordination during catalytic oxidation and found several remarkable axial ligand effects on catalytic oxidation. However, alcoholate and selenolate ligand, which are belonged to chalcogen group same as thiolate, have not ever been examined for researching such relative effect of axial ligand by us and other investigators. Manganese porphyrin coordinated by alkanethiolate also has not yet been reported as an isolated form.
   Now we prepared the first isolable heme alcoholate 1, heme selenolate 2 and manganese heme thiolate 3 in order to investigate the effect of elemental substitution on SR complex on spectroscopic and catalytic properties. We have succeeded in the synthesis of the first heme-alcoholate complexes and the first manganese porphyrin coordinated by thiolate that can retain axial coordination during catalytic oxidizing reaction. We obtained UV-Vis spectra, FT-IR and EPR spectra of these complexes. The N-O stretching mode of complex 1-NO was 60 cm^-1 higher than that of SR-NO and 38 cm^-1 lower than that of an alcohol-ligated heme². Complex 1 had 0.2 V higher E_1/2 (Fe(II)/Fe(III)) than that of SR complex. These two results indicate that electron donative ability of alcoholate is much less than that of thiolate. Catalytic activity of 1 was much lower than that of SR on the oxidation of 2,4,6-tri-tert-butylphenol with perphenylacetic acid, whereas, catalytic activity of complex 3 was comparable to that of SR.

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