LIGHT-ABSORPTION, ELECTRON-PARAMAGNETIC RESONANCE AND RESONANCE RAMAN CHARACTERISTICS OF NITRIDOCHROMIUM(V) PROTOPORPHYRIN-IX AND ITS RECONSTITUTED HEMOPROTEINS

被引:8
作者
HORI, H
TSUBAKI, M
YU, NT
YONETANI, T
机构
[1] GEORGIA INST TECHNOL,SCH CHEM,ATLANTA,GA 30332
[2] HIMEJI INST TECHNOL,FAC SCI,DEPT LIFE SCI,HIMEJI,HYOGO 67122,JAPAN
[3] UNIV PENN,SCH MED,DEPT BIOCHEM & BIOPHYS,PHILADELPHIA,PA 19104
关键词
EPR; RESONANCE RAMAN; NITRIDOCHROMIUM(V)-PORPHYRIN; HEMOPROTEIN;
D O I
10.1016/0167-4838(91)90556-F
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
A surprisingly stable complex of the photolyzed product of azidochromium(III)protoporphyrin-IX was prepared and examined by light absorption, electron paramagnetic resonance (EPR) and resonance Raman spectroscopies. The characteristic EPR spectrum for this complex was consistent with a nitridochromium(V)-porphyrin complex which was two oxidation equivalents above the resting Cr(III) complex. The Cr(V)-N stretching mode was observed at 1010 cm-1 by resonance Raman spectroscopy. A simple diatomic harmonic oscillation model gave a force constant of 6.7 mdyn/angstrom for the Cr(V)-N bond, in the region characteristic for the metal-nitrogen triple bond. Nitridochromium(V) protoporphyrin-IX reconstituted myoglobin and cytochrome c peroxidase were prepared for the first time. The nitridochromium(V)-porphyrins in these apo-proteins were unstable in contrast with the protein-free chromium(V)porphyrin. Upon irradiation of the azide complexes of the chromium(III) protoporphyrin-IX reconstituted myoglobin and cytochrome c peroxidase with ultraviolet light aerobically at room temperature, the characteristic optical and EPR spectra for nitridochromium(V) derivatives were observed. The optical spectra of these photo-induced products were different from those of the nitridochromium(V) protoporphyrin-IX reconstituted hemoproteins. The electrochemical structures of the unusual metalloporphyrin seemed to be modulated by the heme surrounding amino acid residues.
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页码:392 / 399
页数:8
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