PMID: 6988217Mar 1, 1980Paper

Flavocytochrome b2 (Baker's yeast). Deuterium isotope effect studied by rapid-kinetic methods as a probe for the mechanism of electron transfer

European Journal of Biochemistry
D PomponF Lederer

Abstract

The use of DL-[2-2H]lactate in steady-state measurements of ferricyanide reduction by flavocytochrome b2 at 30 degrees C has previously yielded an isotope effect of 5 [F. Lederer (1974) Eur. J. Biochem. 46, 393--399]. We report here studies carried out at 5 degrees C with L-[2-2H]lactate, where flavin and heme reduction were observed in the stopped-flow apparatus, in the absence of acceptor. The generally biphasic reduction curves were analysed according to a new mathematical treatment which allowed us to derive microscopic constants from initial reduction rates. It has thus been possible to determine an isotope effect of 8 on flavin reduction, 6 on heme reduction, compared to 4 in the steady state. Consequently, two slightly rate-limiting steps occur after the first one where the alpha-hydrogen is abstracted. It has also been possible to calculate the substrate association and dissociation rate constants for intact enzyme. The studies were carried out in parallel on intact and cleaved cytochrome b2. The results suggest that proteolysis affects essentially the steps involved in flavin reduction, and not intramolecular electron transfer steps. Moreover, the experimental data obtained at low rates of electron entry have led us to...Continue Reading

References

Sep 15, 1973·Biochimica Et Biophysica Acta·K YagiN Oishi
Jan 31, 1972·European Journal of Biochemistry·C Jacq, F Lederer
Jan 16, 1974·European Journal of Biochemistry·C Jacq, F Lederer
Jul 23, 1969·Biochemical and Biophysical Research Communications·D J Porter, H J Bright
Mar 1, 1959·The Biochemical Journal·C A APPLEBY, R K MORTON

Citations

Jan 1, 1994·Protein Science : a Publication of the Protein Society·A Balme, F Lederer
Feb 1, 1994·Protein Science : a Publication of the Protein Society·M Tegoni, C Cambillau
Jul 31, 1998·Protein Science : a Publication of the Protein Society·K S Rao, F Lederer
Jul 15, 1984·Experientia·J L Dreyer
Jan 1, 1994·Biochimie·F Lederer
May 3, 2001·Journal of Photochemistry and Photobiology. B, Biology·D BhattacharyaP C Mandal
Mar 27, 1999·Journal of Photochemistry and Photobiology. B, Biology·D BhattacharyaP C Mandal
May 1, 1987·Proceedings of the National Academy of Sciences of the United States of America·Z X XiaF S Mathews
Nov 1, 1981·European Journal of Biochemistry·R Ghrir, F Lederer
Aug 1, 1983·European Journal of Biochemistry·P UrbanF Lederer
Oct 15, 1984·European Journal of Biochemistry·P Urban, F Lederer
Dec 15, 1988·European Journal of Biochemistry·G A ReidS K Chapman
Apr 1, 1992·Protein Science : a Publication of the Protein Society·F Lederer
May 26, 2016·Physical Chemistry Chemical Physics : PCCP·N GilletV Moliner
Jul 3, 1995·Biochimica Et Biophysica Acta·D BhattacharyaP C Mandal

Related Concepts

Deuterons
Respiratory Chain
Flavoproteins
Isotope Labeling, Stable
Lactate Dehydrogenase
Lactates
Mathematics
Saccharomyces cerevisiae
L-Lactate dehydrogenase (cytochrome)

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