Driving-force effects on the rate of long-range electron transfer in ruthenium-modified cytochrome C

Journal Article · Wed Jun 07 04:00:00 EDT 1989 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00194a030· OSTI ID:6971186

Meade, T J; Gray, H B ^[1]; Winkler, J R ^[2]

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1. Arthur Amos Noyes Lab., Pasadena, CA (USA)
2. Brookhaven National Lab., Upton, NY (USA)

Two new Ru-modified, Zn-substituted derivatives of horse heart cytochrome c have been prepared, Rua{sub 4}L(histidine-33)-Zn-cyt c (a = NH{sub 3}; L = pyridine, isonicotinamide). Molecular mechanics modeling indicates that the 11.7 {angstrom} edge-to-edge separation between the redox centers is virtually identical with that reported for the Ru-pentaammine derivative. Rates of photoinduced charge separation and recombination in Rua{sub 4}L (His-33)-Zn-cyt c lie in the range of 2.0 {times} 10{sup 5}-3.3 {times} 10{sup 6} s{sup {minus}1} (22{degree}C). These kinetics, along with those already reported, provide a total of eight intramolecular electron-transfer reactions that have been measured in Ru-M-cyt c (M = Fe, Zn) at driving forces (-{Delta}G{degree}) ranging from 0.18 to 1.05 eV. The variation of the rate with driving force is in general agreement with the semiclassical theory of electron-transfer reactions. Fitting the Ru-Zn-cyt c charge-separation data yields a reorganization energy ({lambda}) of 1.15 (5) eV and an electronic coupling matrix element (H{sub AB}) of 0.13 (1) cm{sup {minus}1}. The charge-recombination data are fit with the parameters {lambda} = 1.24 (5) eV and H{sub AB} = 0.10 (1) cm{sup {minus}1}, and the Ru-Fe cyt c electron-transfer rate can be described with {lambda} = 1.2 eV and H{sub AB} = 0.03 cm{sup {minus}1}.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6971186
• Journal Information: Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:12; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
550000 -- Biomedical Sciences
Basic Studies
550500 -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
CALCULATION METHODS
CYTOCHROMES
DATA
DATA ANALYSIS
ELECTRON TRANSFER
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MEASURING METHODS
METALLOPROTEINS
METALS
MOLECULAR MODELS
NUMERICAL DATA
ORGANIC COMPOUNDS
PIGMENTS
PLATINUM METALS
PROTEINS
RUTHENIUM
TRANSITION ELEMENTS