C. L. Tober, P. Nicholls, J. Brodie
Jun 1, 1970
Citations
0
Influential Citations
18
Citations
Journal
Archives of biochemistry and biophysics
Abstract
Abstract The interaction of a series of fluorosuccinic acids with soluble succinate dehydrogenase was examined. 2,2-Difluorosuccinate is converted to monofluorofumarate by the dehydrogenase with a Vmax about 0.25% and a Km approximately 15 times higher than succinate. The reaction is a nonoxidative elimination and is competitively inhibited by malonate to the same degree as the natural substrate. Di-, tri-, and perfluorosuccinic acids and mono- and difluorofumaric acids are all competitive inhibitors of succinate oxidation with respective K values of 4.0, 1.3, 1.1, 0.33, and 1.2 m m . Monofluorosuccinate gives a spectrum with the dehydrogenase similar to that produced by succinate. Difluorosuccinate and difluorofumarate give spectra that initially resemble those obtained with malonate or fumarate but change to resemble the spectrum obtained with malate or oxaloacetate. dl -Monofluorosuccinate is also oxidized by soluble succinate dehydrogenase with an apparent Vmax about 45% that of succinate and a Km approximately five times greater. Enzymatically generated l -monofluorosuccinate had a Vmax approaching that of succinate. The reactions of soluble succinic dehydrogenase with succinate and with monofluorosuccinate are treated according to a simplified version of the mechanism previously postulated by Zeylemaker et al. The enzyme catalyzed elimination of HF from difluorosuccinate is used as a model for an ionic hydrogen elimination mechanism occurring with the true substrates that reduce hydrogen acceptors.