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Titolo:
Kinetics and mechanism of the outer-sphere oxidation of horse-heart cytochrome c by an anionic chromium(v) complex - Kinetic evidence for precursor formation and a late electron-transfer transition state
Autore:
Korner, M; van Eldik, R;
Indirizzi:
Univ Erlangen Nurnberg, Inst Inorgan Chem, D-91058 Erlangen, Germany Univ Erlangen Nurnberg Erlangen Germany D-91058 -91058 Erlangen, Germany
Titolo Testata:
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
fascicolo: 10, , anno: 1999,
pagine: 1805 - 1812
SICI:
1434-1948(199910):10<1805:KAMOTO>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
CARBOXYLATO-BOUND CHROMIUM(V); LIGAND-EXCHANGE REACTIONS; FERRICYTOCHROME-C; REACTION VOLUMES; INDUCED CANCERS; REDOX REACTIONS; DNA CLEAVAGE; REDUCTION; ELECTROCHEMISTRY; PH;
Keywords:
cytochrome c; chromium(v); saturation kinetics; separation of K and k(ET); volume profile; kinetics;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
71
Recensione:
Indirizzi per estratti:
Indirizzo: Korner, M Univ Erlangen Nurnberg, Inst Inorgan Chem, Egerlandstr 1, D-91058 Erlangen, Germany Univ Erlangen Nurnberg Egerlandstr 1 Erlangen Germany D-91058 y
Citazione:
M. Korner e R. van Eldik, "Kinetics and mechanism of the outer-sphere oxidation of horse-heart cytochrome c by an anionic chromium(v) complex - Kinetic evidence for precursor formation and a late electron-transfer transition state", EUR J INORG, (10), 1999, pp. 1805-1812

Abstract

The irreversible outer-sphere electron-transfer reaction between trans-bis(2-ethyl-2-hydroxybutanoato(2-))oxochromate(v) and cytochrome c(II) was investigated as a function of pH, concentration, temperature and pressure. The plot of the observed pseudo-first order rate constant as a function of the Cr-V concentration shows a clear trend towards saturation at higher Cr-V concentrations, from which the precursor formation constant and the electron-transfer rate constant could be separated (K = 37 +/- 5 M-1 and k(ET) = 1510 +/- 180 s(-1) at pH 4.8 and 279 K). In the low CrV concentration range the second-order electron-transfer rate contants were measured as a function of temperature (Delta H-double dagger = 20.9 +/- 0.6 kJ mol(-1); Delta S-double dagger = -79.9 +/- 2.1 J K-1 mol(-1); Delta G(double dagger) (279 K)= 43.2 kJ mol(-1)). High-pressure experiments were performed at two different pH values. The kinetic (stopped-flow) and thermodynamic (electrochemical) measurements as a function of pressure enabled the construction of a volume profile for the system at 279 K. The activation volumes for the redox process are 9.2 +/- 0.2 (pH 5.0) and -11.1 +/- 0.8 cm(3) mol(-1) (pH 4.7), and the overall reaction volumes were estimated to be -7 +/- 2 (pH 5.0) and -10 +/- 2 cm(3) mol(-1) (pH 4.7). The transition state of the redox reaction Lies to a large extent on the product side and can be described as "late". The results are discussed in comparison to earlier measurements using cobalt and ruthenium complexes as reaction partners for cytochrome c.

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Documento generato il 26/09/20 alle ore 08:28:15