Kimura Y, Kojyo T, Kimura I, Sato M
Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-Cho, Kagawa, 761-07, Japan.
Arch Microbiol. 1998 Sep;170(3):179-84. doi: 10.1007/s002030050631.
An acyl-coenzyme A carboxylase that carboxylates acetyl-CoA, butyryl-CoA, propionyl-CoA, and succinyl-CoA was purified from Myxococcus xanthus. Since the enzyme showed maximal rates of carboxylation with propionyl-CoA, the enzyme is thought to be propionyl-CoA carboxylase. The apparent Km values for acetyl-CoA, butyryl-CoA, propionyl-CoA, and succinyl-CoA were found to be 0.2, 0. 2, 0.03, and 1.0 mM, respectively. The native enzyme has a molecular mass of 605-615 kDa and is composed of nonidentical subunits (alpha and beta) with molecular masses of 53 and 56 kDa, respectively. The enzyme showed maximal activity at pH 7.0-7.5 and at 25-30 degrees C, and was affected by variation in concentrations of ATP and Mg2+. During development of M. xanthus, the propionyl-CoA carboxylase activity increased gradually, with maximum activity observed during the sporulation stage. Previous work has shown that a propionyl-CoA-carboxylase-deficient mutant of M. xanthus reduces levels of long-chain fatty acids. These results suggest that the propionyl-CoA carboxylase is also responsible for the carboxylation of acetyl-CoA to malonyl-CoA used for the synthesis of long-chain fatty acids during development.
从黄色粘球菌中纯化出一种能使乙酰辅酶A、丁酰辅酶A、丙酰辅酶A和琥珀酰辅酶A羧化的酰基辅酶A羧化酶。由于该酶对丙酰辅酶A的羧化速率最高，因此被认为是丙酰辅酶A羧化酶。乙酰辅酶A、丁酰辅酶A、丙酰辅酶A和琥珀酰辅酶A的表观Km值分别为0.2、0.2、0.03和1.0 mM。天然酶的分子量为605 - 615 kDa，由分子量分别为53 kDa和56 kDa的不同亚基（α和β）组成。该酶在pH 7.0 - 7.5和25 - 30℃时表现出最大活性，并受ATP和Mg2 +浓度变化的影响。在黄色粘球菌发育过程中，丙酰辅酶A羧化酶活性逐渐增加，在孢子形成阶段观察到最大活性。先前的研究表明，黄色粘球菌的丙酰辅酶A羧化酶缺陷型突变体可降低长链脂肪酸水平。这些结果表明，丙酰辅酶A羧化酶在发育过程中也负责将乙酰辅酶A羧化为用于合成长链脂肪酸的丙二酰辅酶A。
