TIME-RESOLVED MAGNETIC CIRCULAR-DICHROISM SPECTROSCOPY OF PHOTOLYZED CARBONMONOXY CYTOCHROME-C-OXIDASE (CYTOCHROME-AA3)

被引：23

作者：

GOLDBECK, RA ^{[1
]}

DAWES, TD ^{[1
]}

EINARSDOTTIR, O ^{[1
]}

WOODRUFF, WH ^{[1
]}

KLIGER, DS ^{[1
]}

机构：

[1] UNIV CALIF LOS ALAMOS SCI LAB,ISOTOPE & STRUCT CHEM GRP INC 4,LOS ALAMOS,NM 87545

来源：

BIOPHYSICAL JOURNAL | 1991年 / 60卷 / 01期

关键词：

D O I：

10.1016/S0006-3495(91)82036-7

中图分类号：

Q6 [生物物理学];

学科分类号：

071011 ;

摘要：

Nanosecond time-resolved magnetic circular dichroism (TRMCD) and time-resolved natural circular dichroism (TRCD) measurements of photolysis products of the CO complex of eukaryotic cytochrome c oxidase (CcO-CO) are presented. TRMCD spectra obtained at 100 ns and 10-mu-s after photolysis are diagnostic of pentacoordinate cytochrome a3 Fe2+, as would be expected for simple photodissociation. Other time-resolved spectroscopies (UV-visible and resonance Raman), however, show evidence for unusual Fe(a3)2+ coordination after CO photolysis (Woodruff, W. H., O. Einarsdottir, R. B. Dyer, K. A. Bagley, G. Palmer, S. J. Atherton, R. A. Goldbeck, T. D. Dawes, and D. S. Kliger. 1991. Proc. Nat. Acad. Sci, U.S.A. 88:2588-2592). Furthermore, time-resolved IR experiments have shown that photodissociated CO binds to Cu(b)+ prior to recombining with Fe(a3)2+ (Dyer, R. B., O. Einarsdottir, P. M. Killough, J. J. Lopez-Garriga, and W. H. Woodruff. 1989. J. Am. Chem. Soc. 111:7657-7659). A model of the CcO-CO photolysis cycle which is consistent with all of the spectroscopic results is presented. A novel feature of this model is the coordination of a ligand endogenous to the protein to the Fe axial site vacated by the photolyzed CO and the simultaneous breaking of the Fe-imidazole(histidine) bond.

引用

页码：125 / 134

页数：10

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