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Mechanistic studies with general acyl-CoA dehydrogenase and butyryl-CoA dehydrogenase : evidence for the transfer of the beta-hydrogen to the flavin N(5)-position as a hydride

Mechanistic studies with general acyl-CoA dehydrogenase and butyryl-CoA dehydrogenase : evidence for the transfer of the beta-hydrogen to the flavin N(5)-position as a hydride

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GHISLA, Sandro, Colin THORPE, Vincent MASSEY, 1984. Mechanistic studies with general acyl-CoA dehydrogenase and butyryl-CoA dehydrogenase : evidence for the transfer of the beta-hydrogen to the flavin N(5)-position as a hydride. In: Journal of Biochemistry. 23(14), pp. 3154-3161. ISSN 0006-2960. eISSN 1520-4995

@article{Ghisla1984Mecha-8162, title={Mechanistic studies with general acyl-CoA dehydrogenase and butyryl-CoA dehydrogenase : evidence for the transfer of the beta-hydrogen to the flavin N(5)-position as a hydride}, year={1984}, doi={10.1021/bi00309a008}, number={14}, volume={23}, issn={0006-2960}, journal={Journal of Biochemistry}, pages={3154--3161}, author={Ghisla, Sandro and Thorpe, Colin and Massey, Vincent} }

Massey, Vincent Ghisla, Sandro application/pdf Ghisla, Sandro Thorpe, Colin eng Thorpe, Colin Massey, Vincent deposit-license First publ. in: Journal of Biochemistry 23 (1984), 14, pp. 3154-3161 Butyryl-CoA dehydrogenase from Megasphera elsdenii catalyzes the exchange of the α- and β-hydrogens of substrate with solvent [Gomes, B., Fendrich, G., & Abeles, R. H. (1981) Biochemistry 20,1481-1490]. The stoichiometry of this exchange was determined by using 3H20 label as 1.94 ± 0.1 per substrate molecule. The rate of 3H label incorporation into substrate under anaerobic conditions is monophasic, indicating that both the α- and β-hydrogens exchange at the same rate. The exchange in ,HzO leads to incorporation of one 2H each into the α- and the β-positions of butyryl-CoA, as determined by companion 'H NMR experiments and confirmed by mass spectroscopic analysis. In contrast, with general acyl-CoA dehydrogenase from pig kidney, only exchange of the a-hydrogen was found. The β-hydrogen is the one that is transferred (reversibly) to the flavin 5-position during substrate dehydrogenation. This was demonstrated by reacting 5-3H- and 5-2H-reduced 5-deaza-FAD-general acyl-CoA dehydrogenase with crotonyl-CoA. Only one face of the reduced flavin analogue is capable of transferring hydrogen to substrate. The rate of this reaction is 11.1 s-1 for 5-deaza-FAD-enzyme and 2.2 s-1 for [5-2H]deaza-FAD-enzyme, yielding an isotope effect of 5. These values compare with a rate of 2.6 s-1 for the reaction of native reduced enzyme with crotonyl-CoA. The two reduced enzymes (normal vs. 5-deaza-FAD-enzyme) thus react at similar rates, indicating a similar mechanism. The results are interpreted as evidence for a catalytic sequence in which the α-hydrogen is abstracted as a proton, followed by expulsion of the β-hydrogen as a hydride and its direct transfer to the flavin position. 1984 2011-03-24T17:41:04Z Mechanistic studies with general acyl-CoA dehydrogenase and butyryl-CoA dehydrogenase : evidence for the transfer of the beta-hydrogen to the flavin N(5)-position as a hydride 2011-03-24T17:41:04Z

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