Grunnet I, Knudsen J
Biochem J. 1983 Jan 1;209(1):215-22. doi: 10.1042/bj2090215.
Fatty acid synthetase from goat mammary gland was subjected to limited proteolysis by trypsin and elastase. Both proteolytic enzymes selectively cleaved the chain-terminating thioester hydrolase component from the enzyme complex, leaving all other partial activities intact in the core peptides. Trypsin, but not elastase, caused extensive degradation of the released thioester hydrolase. The released thioester hydrolase could be purified to homogeneity by gel filtration. The molecular weight was estimated as 29 000 and the enzyme showed only significant hydrolytic activity toward long-chain acyl-CoA esters. The core peptides retained the ability to synthesize medium-chain acyl-CoA esters in the presence of 2,6-di-O-methyl-alpha-cyclodextrin. The results conclusively show that the terminating thioester hydrolase of goat mammary-gland fatty acid synthetase is not involved in termination of medium-chain-length fatty acid synthesis by this enzyme.
山羊乳腺脂肪酸合成酶用胰蛋白酶和弹性蛋白酶进行了有限的蛋白水解。这两种蛋白水解酶都从酶复合物中选择性地切割链终止硫酯水解酶成分，使核心肽中的所有其他部分活性保持完整。胰蛋白酶而非弹性蛋白酶导致释放的硫酯水解酶发生广泛降解。释放的硫酯水解酶可通过凝胶过滤纯化至同质。分子量估计为29000，该酶仅对长链酰基辅酶A酯显示出显著的水解活性。在2,6-二-O-甲基-α-环糊精存在下，核心肽保留了合成中链酰基辅酶A酯的能力。结果确凿地表明，山羊乳腺脂肪酸合成酶的终止硫酯水解酶不参与该酶对中链长度脂肪酸合成的终止。
