Uchida Y, Izai K, Orii T, Hashimoto T
Department of Pediatrics, Gifu University School of Medicine, Japan.
J Biol Chem. 1992 Jan 15;267(2):1034-41.
Long-chain 3-hydroxyacyl-CoA dehydrogenase was extracted from the washed membrane fraction of frozen rat liver mitochondria with buffer containing detergent and then was purified. This enzyme is an oligomer with a molecular mass of 460 kDa and consisted of 4 mol of large polypeptide (79 kDa) and 4 mol of small polypeptides (51 and 49 kDa). The purified enzyme preparation was concluded to be free from the following enzymes based on marked differences in behavior of the enzyme during purification, molecular masses of the native enzyme and subunits, and immunochemical properties: enoyl-CoA hydratase, short-chain 3-hydroxyacyl-CoA dehydrogenase, peroxisomal enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, and mitochondrial and peroxisomal 3-ketoacyl-CoA thiolases. The purified enzyme exhibited activities toward enoyl-CoA hydratase and 3-ketoacyl-CoA thiolase together with the long-chain 3-hydroxyacyl-CoA dehydrogenase activity. The carbon chain length specificities of these three activities of this enzyme differed from those of the other enzymes. Therefore, it is concluded that this enzyme is not long-chain 3-hydroxyacyl-CoA dehydrogenase; rather, it is enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase trifunctional protein.
长链3-羟酰基辅酶A脱氢酶是从冷冻大鼠肝脏线粒体的洗涤膜部分中，用含有去污剂的缓冲液提取，然后进行纯化的。这种酶是一种分子量为460 kDa的寡聚体，由4摩尔大的多肽（79 kDa）和4摩尔小的多肽（51 kDa和49 kDa）组成。基于该酶在纯化过程中的行为、天然酶和亚基的分子量以及免疫化学性质的显著差异，纯化后的酶制剂被认为不含以下几种酶：烯酰基辅酶A水合酶、短链3-羟酰基辅酶A脱氢酶、过氧化物酶体烯酰基辅酶A水合酶/3-羟酰基辅酶A脱氢酶双功能蛋白以及线粒体和过氧化物酶体3-酮酰基辅酶A硫解酶。纯化后的酶除了具有长链3-羟酰基辅酶A脱氢酶活性外，还表现出烯酰基辅酶A水合酶和3-酮酰基辅酶A硫解酶的活性。该酶这三种活性的碳链长度特异性与其他酶不同。因此，可以得出结论，这种酶不是长链3-羟酰基辅酶A脱氢酶；相反，它是烯酰基辅酶A水合酶/3-羟酰基辅酶A脱氢酶/3-酮酰基辅酶A硫解酶三功能蛋白。
