Abstract
We have used zinc-substituted hemoproteins to study long-range electron transfer between redox centers at fixed and known distances. The photo-excited zinc triplet state in one subunit of the α1-β2 electron transfer complex of [Zn,Fe] hybrid hemoglobin transfers an electron to its partner aquoferriheme subunit at a rate, kt=100 s-1. The temperature dependence of this electron transfer from 77K to 313K is indicative of non-adiabatic electron tunnelling in which the accompanying nuclear rearrangements proceed by nuclear tunnelling. For the complex between zinc-substituted yeast cytochrome c peroxidase (CCP) and native yeast cytochrome c, electron transfer occurs at a rate, kt=138 s-1, compared to kt = 17 s-1 in the complex between the yeast enzyme and horse cyt c. The difference demonstrates the species specificity involved in physiological electron transfer. Oxidation of ferroporphyrin by the zinc porphyrin radical is more rapid, and, for the yeast cytochrome, occurs with a rate, kh ∼ 104 s-1.
Original language | English (US) |
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Pages (from-to) | 125-133 |
Number of pages | 9 |
Journal | Coordination Chemistry Reviews |
Volume | 64 |
Issue number | C |
DOIs | |
State | Published - May 1985 |
Funding
This work has been supported by NIH Grant HL13531'and NSF Grant PCM 76-81304. It has been encouraged by stimulating discussions with H.B. Gray, S. Iseid, G. McLendon, J. Miller, M.A. Ratner, and R.P. Van Duyne.
ASJC Scopus subject areas
- General Chemistry
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry