SUBSTITUTED TETRAAMMINERUTHENIUM CYTOCHROME-C DERIVATIVES - CHEMISTRY AND ELECTRON-TRANSFER REACTIONS

被引：18
作者：
SUN, J
WISHART, JF
GARDINEER, MB
CHO, MOP
ISIED, SS
机构：
[1] RUTGERS STATE UNIV,DEPT CHEM,NEW BRUNSWICK,NJ 08903
[2] BROOKHAVEN NATL LAB,UPTON,NY 11973
来源：
INORGANIC CHEMISTRY | 1995年 / 34卷 / 12期
关键词：
D O I：
10.1021/ic00116a024
中图分类号：
O61 [无机化学];
学科分类号：
070301 ; 081704 ;
摘要：
Horse-heart (hh) cytochrome c, modified at His-33, and Candida krusei (Ck) cytochrome c, modified at His-39, with a series of cis- and trans-[L(NH3)(4)Ru(III)cyt c] derivatives, where L is isonicotinamide (isn) or pyridine (py), have been prepared and characterized. Rate constants for intramolecular electron transfer from the heme(II) to Ru(III) in the [L(NH3)(4)Ru(III)cyt c(II)] intermediates generated by oxidative pulse radiolysis of the fully reduced modified protein species were as follows (k (s(-1)), Delta H-double dagger (kcal mol(-1)), Delta S-double dagger (cal deg(-1)mol(-1)), -Delta G degrees (eV)): 440, 7.3, -22, 0.18 for L = trans-isn (hh); 440, 6.2, -26, 0.18 for L = cis-isn (hh); 126, 8.8, -19, 0.11 for L = trans-py (hh); 220, 6.4, -27, 0.13 for L = trans-isn (Ck); 154, 2.3, -41, 0.18 for L = NH3 (Ck). Relative differences in the rates are accounted for by variations in the driving force and reorganization energies in these ruthenium-modified proteins resulting from the nature of the ligands around the ruthenium center and from the different sites of modification on the cytochrome. The fully oxidized [L(NH3)(4)Ru(III)cyt c(III)] species undergo slow redox disproportionation reactions (k = 35 M(-1) s(-1), pH 7.0) which have been studied by optical and electrochemical methods. The Ru(IV) species thus created subsequently rearranges in an irreversible manner. In the presence of excess oxidant, all of the bound ruthenium is converted to the rearranged form. To avoid this problem, the [L(NH3)(4)Ru(III)cyt c(II)] intermediates for intramolecular electron-transfer studies were generated from the stable [L(NH3)(4)Ru(II)cyt c(II)] form.
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页码：3301 / 3309
页数：9
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