Electron-transfer kinetics of Zn substituted cytochrome c and its Ru(NH/sub 3/)/sub 5/(Histidine-33) derivative

Journal Article · Wed Jan 20 04:00:00 EST 1988 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00210a019· OSTI ID:5648887

Elias, H; Chou, M H; Winkler, J R

The kinetics of the bimolecular electron transfers from triplet-excited zinc-substituted horse heart cytochrome c (Zn-cyt c*) to Ru(NH/sub 3/)/sub 5/L/sup 3 +/ have been measured (L = NH/sub 3/, k(298 K) = 1.4 x 10/sup 7/ M/sup -1/ s/sup -1/; L = histidine, k(298 K) = 2.4 x 10/sup 7/ M/sup -1/ s/sup -1/), along with those of the corresponding thermal back-reactions (L = NH/sub 3/, k(298 K) = 1.5 x 10/sup 8/ M/sup -1/ s/sup -1/; L = histidine, k(298 K) = 3.6 x 10/sup 8/ M/sup -1/ s/sup -1/). The derivatized metalloprotein ruthenium pentaammine histidine-33-zinc-substituted cytochrome c (Ru-Zn-cyt c) has been prepared and characterized by atomic absorption spectroscopy and HPLC analysis of its tryptic digestion fragments. The rate of intraprotein electron transfer from the triplet-excited Zn-porphyrin moiety to the 11.8-A distant Ru(NH/sub 3/)/sub 5/(His-33)/sup 3 +/ residue (k(298 K) = 7.7 x 10/sup 5/ s/sup -1/), as well as that of the thermal back-reaction (k(298 K) = 1.6 x 10/sup 6/ s/sup -1/), has been measured by transient spectroscopy. Intraprotein electron transfer from Ru(II) quenches Zn-cyt c* with a rate constant of 2.4 x 10/sup 2/ s/sup -1/. These kinetics are discussed in terms of the semiclassical theory of electron-transfer reactions.

• Research Organization: Brookhaven National Lab., Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5648887
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:2; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHROMATOGRAPHY
COMPLEXES
CYTOCHROMES
DATA
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
INFORMATION
KINETICS
LIQUID COLUMN CHROMATOGRAPHY
MULTIPLETS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
REACTION KINETICS
RUTHENIUM COMPLEXES
SEPARATION PROCESSES
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
TRIPLETS
ZINC COMPOUNDS