Branched Chain α-Keto Acid Metabolism

作者：Jerald L. Connelly, Dean J. Danner, Joe A. Bowden · 发表于：Journal of Biological Chemistry · 年份：1968 · DOI：10.1016/s0021-9258(19)56972-1 · 被引用次数：82 · 研究领域：Biochemical Acid Research Studies、Metabolism and Genetic Disorders、Aldose Reductase and Taurine

Abstract A soluble enzyme complex, capable of catalyzing the oxidative decarboxylation of both α-ketoisocaproic and α-keto-β-methylvaleric acids, has been obtained from bovine liver. The purified activity (approximately 70-fold) has a pH optimum of about 7.6 for both substrates and exhibits Km values of 3.5 x 10-3 m and 2.5 x 10-3 m for α-ketoisocaproic and α-keto-β-methylvaleric acids, respectively. The enzyme preparation is highly substrate-specific, being most notably inactive with α-ketoisovalerate. Evidence is given for the separation of enzymes active with the latter acid from α-ketoisocaproate dehydrogenase, and the significance of this phenomenon relative to the genetic disease, branched chain ketoaciduria, is discussed.