Fong J C, Schulz H
J Biol Chem. 1977 Jan 25;252(2):542-7.
A short chain enoyl-CoA hydratase (crotonase) from pig heart has been purified to apparent homogeneity. The enzyme has an estimated native molecular weight of 155,000 and appears to be composed of six subunits of molecular weight 27,300. A study of the kinetic properties of the enzyme revealed that the maximal velocity decreases nearly linearly with increasing chain length of the substrates from 1,670 units/mg with crotonyl-CoA to 40 units/mg with hexadecenoyl-CoA. However, the same Km values of 30 muM were obtained for all substrates except for crotonyl-CoA for which a value of 13 muM was determined. Since the presence of both crotonase and long chain enoyl-CoA hydratase in pig heart has been reported earlier, the presence of the same two enoyl-CoA hydratases in various tissues of several animals was investigated by sequential extraction and chromatography on hydroxylapatite of tissue homogenates. The simultaneous occurrence of both types of enoyl-CoA hydratase in tissues of pig and guinea pig has thus been established. It is proposed that the complementary actions of the two enoyl-CoA hydratases assures a high rate of hydration of enoyl-CoA intermediates of all chain lengths in fatty acid oxidation.
来自猪心脏的一种短链烯酰辅酶A水合酶（巴豆酸酶）已被纯化至表观均一。该酶估计天然分子量为155,000，似乎由六个分子量为27,300的亚基组成。对该酶动力学性质的研究表明，最大速度随着底物链长的增加几乎呈线性下降，从巴豆酰辅酶A的1,670单位/毫克降至十六碳烯酰辅酶A的40单位/毫克。然而，除巴豆酰辅酶A的Km值为13μM外，所有底物的Km值均为30μM。由于此前已报道猪心脏中同时存在巴豆酸酶和长链烯酰辅酶A水合酶，因此通过对组织匀浆进行连续提取并在羟基磷灰石上进行色谱分析，研究了几种动物不同组织中是否存在相同的两种烯酰辅酶A水合酶。由此确定了猪和豚鼠组织中同时存在这两种类型的烯酰辅酶A水合酶。有人提出，这两种烯酰辅酶A水合酶的互补作用确保了脂肪酸氧化过程中所有链长的烯酰辅酶A中间体的高水合速率。
