布氏锥虫
硫辛酸
生物化学
二氢脂酰胺脱氢酶
脱氢酶
酶
生物
辅因子
细胞分离
支链α-酮酸脱氢酶复合物
化学
抗氧化剂
基因
作者
Simon A. Jackman,David W. Hough,Michael J. Danson,Kenneth J. Stevenson,Frederik Opperdoes
出处
期刊:European journal of biochemistry
[Wiley]
日期:1990-10-01
卷期号:193 (1): 91-95
被引量:40
标识
DOI:10.1111/j.1432-1033.1990.tb19308.x
摘要
In the long-slender bloodstream form of Trypanosoma brucei, the enzyme dihydrolipoamide dehydrogenase exists in the absence of the 2-oxo-acid dehydrogenase complexes of which it is normally a component, and appears to be associated with the plasma membrane of the organism [Danson, M. J., Conroy, K., McQuattie, A. & Stevenson, K. J. (1987) Biochem. J. 243, 661-665]. In the present paper, a complete subcellular fractionation of T. brucei has been carried out and, by comparison with marker enzymes, it is confirmed that the dihydrolipoamide dehydrogenase is indeed associated with the plasma membrane. In addition, we now provide evidence that the distribution of the enzyme is over the whole surface of the membrane, including the flagellar pocket region, and that the enzyme is not found in any other cellular fraction. A study of the latency of the enzyme suggests that it is located on the cytoplasmic surface of the plasma membrane. The discovery of the presumed substrate of dihydrolipoamide dehydrogenase, lipoic acid, is reported for T. brucei. Using a biological assay involving a strain of Escherichia coli that requires lipoic acid for growth, we have found that acid-hydrolysed extracts of T. brucei contain 1.7 (+/- 0.2) ng of the cofactor/mg protein. The chemical nature of the lipoic acid was confirmed by gas chromatography/mass spectrometry.
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