人脑海马体中L-谷氨酸脱羧酶的纯化及某些性质

Purification and some properties of L-glutamate decarboxylase from human brain.

作者信息

Blindermann J M, Maitre M, Ossola L, Mandel P

出版信息

Eur J Biochem. 1978 May;86(1):143-52. doi: 10.1111/j.1432-1033.1978.tb12293.x.

DOI:10.1111/j.1432-1033.1978.tb12293.x

Abstract

Glutamate decarboxylase (EC 4.1.1.15) from human brain has been purified 8000-fold with respect to the initial homogenate. The molecular weight of the native enzyme was found to be 140000 by electrophoresis on a polyacrylamide gradient gel slab. The presence of a single protein band (Mr 67000) on sodium dodecylsulphate/polyacrylamide gel and the existence of only one N-terminal amino acid suggest that the enzyme consists of two similar if not identical polypeptide chains. The Km of the enzyme at the optimum pH of 6.8 is about 1.3 x 10(-3) M for glutamate and 0.13 x 10(-6) M for pyridoxal phosphate. The analysis of the effects of various inhibitors of mouse brain glutamate decarboxylase on the human enzyme confirms the strong competitive inhibition caused by 3-mercaptopropionic acid (Ki = 2.7 x 10(-6) M) while the Ki values for allylglycine and chloride ion are 1.8 x 10(-2) M and 2.2 x 10(-2) M, respectively.

摘要

人脑谷氨酸脱羧酶（EC 4.1.1.15）相对于初始匀浆已纯化了8000倍。通过在聚丙烯酰胺梯度凝胶板上进行电泳，发现天然酶的分子量为140000。在十二烷基硫酸钠/聚丙烯酰胺凝胶上出现单一蛋白条带（Mr 67000）以及仅存在一个N端氨基酸表明该酶由两条相似（即便不是完全相同）的多肽链组成。该酶在最适pH 6.8时对谷氨酸的Km约为1.3×10⁻³ M，对磷酸吡哆醛的Km为0.13×10⁻⁶ M。对小鼠脑谷氨酸脱羧酶的各种抑制剂对人酶作用的分析证实了3-巯基丙酸引起的强烈竞争性抑制（Ki = 2.7×10⁻⁶ M），而烯丙基甘氨酸和氯离子的Ki值分别为1.8×10⁻² M和2.2×10⁻² M。