Machicao F, Wieland O H
Hoppe Seylers Z Physiol Chem. 1980 Jul;361(7):1093-106. doi: 10.1515/bchm2.1980.361.2.1093.
The pyruvate dehydrogenase complex has been isolated from bovine kidney mitochondria under special anti-proteolytic conditions yielding preparations with a specific activity of up to 20 U/mg protein. Dihydrolipoamide acetyltransferase resolved from the complex was subjected to limited proteolysis resulting in the formation of two major fragments with apparent molecular weights of 36000 and 28000. The fragments were isolated by extraction from dodecyl sulfate polyacrylamide gels and were both shown to possess enzymatic activity for acetyl transfer. Acetylation studies indicated that each fragment contains one protein-bound lipoyl group. It is concluded that the kidney dihydrolipoamide acetyltransferase subunit consists of two homologous if not identical domains. A model is suggested where the acetyltransferase core of the mammalian pyruvate dehydrogenase complex is made up of 30 polypeptide chains whose 60 domains could be arranged in pentagonal dodecahedron symmetry quite similar as proposed for the 60 subunit structure of the acetyltransferase core.
丙酮酸脱氢酶复合体是在特殊的抗蛋白水解条件下从牛肾线粒体中分离得到的，所获制剂的比活性高达20 U/mg蛋白质。从该复合体中解析出的二氢硫辛酰胺乙酰转移酶经有限蛋白水解后，形成了两个主要片段，其表观分子量分别为36000和28000。通过从十二烷基硫酸钠聚丙烯酰胺凝胶中提取分离出这些片段，结果表明二者均具有乙酰转移酶活性。乙酰化研究表明，每个片段均含有一个与蛋白质结合的硫辛酰基。由此得出结论，肾二氢硫辛酰胺乙酰转移酶亚基由两个同源（即便不是完全相同）的结构域组成。有人提出了一个模型，即哺乳动物丙酮酸脱氢酶复合体的乙酰转移酶核心由30条多肽链组成，其60个结构域可以呈五角十二面体对称排列，这与所提出的乙酰转移酶核心的60亚基结构颇为相似。
