Properties of α-Amino-ε-caprolactam Racemase from Achromobacter obae
Properties of α-Amino-ε-caprolactam Racemase from Achromobacter obae
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无色杆菌 α-氨基-ε-己内酰胺消旋酶的性质
DOI：
10.1271/bbb1961.47.1887
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
K. Soda
中科院分区：
文献类型：
--
作者：
S. A. Ahmed;N. Esaki;Hidehiko Tanaka;K. Soda
α-氨基-e-己内酰胺消旋酶（α-氨基-e-己内酰胺消旋酶）是一种存在于obae无色杆菌细胞质部分的酶。它具有单体结构，分子量约为50,000。在pH 7.3下，酶的吸收光谱在280 nm和412 nm处达到最大值，与pH 6.0 ~ 8.0无关。每摩尔酶结合一摩尔吡哆醛5 ' -磷酸。酶与羟胺的孵育导致了脱酶的形成。d-和1 -α-氨基-e-己内酰胺是唯一的底物。两种异构体的最大活性均在pH 8.8时发现。Michaelis常数为：d-α-氨基-e-己内酰胺为8 mm， l-α-氨基-e-己内酰胺为6mm， 5′-磷酸吡哆醛为2.1 × 10−7 m。该酶被CuSO4、HgCl2、硫醇试剂（如n -乙基马来酰亚胺和对氯脲苯甲酸酯）和羰基试剂（如苯肼和羟胺）显著抑制。α-氨基-e-己内酰胺消旋酶催化底物α-质子交换。
α-Amino-e-caprolactam racemase, which occurs in the cytoplasmic fraction of Achromobacter obae, has been purified to homogeneity. It has a monomeric structure with a molecular weight of approximately 50,000. The absorption spectrum of the enzyme exhibits maxima at 280 and 412 nm at pH 7.3, and is independent of pH from 6.0 to 8.0. One mole of pyridoxal 5′-phosphate is bound per mol of the enzyme. Incubation of the enzyme with hydroxylamine resulted in the formation of the apoenzyme. d- and l-α-Amino-e-caprolactams are the only substrates. The maximum activity is found at pH 8.8 for both the isomers. Michaelis constants are as follows: 8 mm for d-α-amino-e-caprolactam, 6mm for l-α-amino-e-caprolactam and 2.1 × 10−7 m for pyridoxal 5′-phosphate. The enzyme is inhibited significantly by CuSO4, HgCl2, thiol reagents such as N-ethylmaleimide and p-chloromercuribenzoate, and carbonyl reagents (e.g., phenylhydrazine and hydroxylamine). α-Amino-e-caprolactam racemase catalyzes the α-proton exchange of the substra...