Danson M J, Conroy K, McQuattie A, Stevenson K J
Department of Biochemistry, University of Bath, Claverton Down, U.K.
Biochem J. 1987 May 1;243(3):661-5. doi: 10.1042/bj2430661.
Dihydrolipoamide dehydrogenase has been discovered in the bloodstream form of the eukaryotic African parasite, Trypanosoma brucei. The enzyme catalysed the stoichiometric oxidation of dihydrolipoamide by NAD+ and exhibited a hyperbolic dependence of catalytic activity on the concentrations of both dihydrolipoamide and NAD+. Chemical modification with the tervalent arsenical reagent p-aminophenyldichloroarsine indicates the involvement in catalysis of a reversibly reducible disulphide bond. Plasma-membrane sheets were purified from T. brucei, and it was shown that virtually all the dihydrolipoamide dehydrogenase remained closely associated with this membrane preparation. T. brucei apparently lacks the 2-oxoacid dehydrogenase multienzyme complexes of which dihydrolipoamide dehydrogenase is usually an integral component. In the context of this absence, the possible function of trypanosomal dihydrolipoamide dehydrogenase is discussed, with particular reference to its cellular location in the plasma membrane.
在真核生物非洲寄生虫布氏锥虫的血流形式中发现了二氢硫辛酰胺脱氢酶。该酶催化NAD⁺对二氢硫辛酰胺进行化学计量的氧化反应,并且其催化活性对二氢硫辛酰胺和NAD⁺的浓度均呈双曲线依赖性。用三价砷试剂对氨基苯基二氯胂进行化学修饰表明,一个可逆还原的二硫键参与了催化过程。从布氏锥虫中纯化出质膜片层,结果表明几乎所有的二氢硫辛酰胺脱氢酶都与这种膜制剂紧密结合。布氏锥虫显然缺乏二氢硫辛酰胺脱氢酶通常作为其组成部分的2-氧代酸脱氢酶多酶复合物。在此种缺失的背景下,讨论了锥虫二氢硫辛酰胺脱氢酶的可能功能,特别提及了它在质膜中的细胞定位。