人脑谷氨酰胺合成酶：纯化与特性鉴定

Glutamine synthetase of the human brain: purification and characterization.

作者信息

Yamamoto H, Konno H, Yamamoto T, Ito K, Mizugaki M, Iwasaki Y

出版信息

J Neurochem. 1987 Aug;49(2):603-9. doi: 10.1111/j.1471-4159.1987.tb02906.x.

DOI:10.1111/j.1471-4159.1987.tb02906.x

Abstract

Glutamine synthetase (GS) isolated from human brain formed a single band on sodium dodecyl sulfate-polyacrylamide gel with a molecular weight of 44,000. The enzyme had a specific activity of 179.2 U/mg protein when assayed by measuring the rate of the formation of gamma-glutamylhydroxamate using hydroxylamine as a substrate. In the presence of manganese ions, the relative activity of human brain GS was much lower than that of the sheep brain enzyme. The suppression of activity by increasing the ADP concentration, however, was less marked in the human enzyme than that in the sheep enzyme. Antibodies were raised in rabbits against the purified enzyme. The double-immunodiffusion technique disclosed cross-reactivities among GSs isolated from human, sheep, and rat brains, but the enzymes were not immunologically identical. Immunohistochemically, GS was localized in the cytoplasm of astrocytes in the human and rat brains and in pericentral hepatocytes of the liver.

摘要

从人脑中分离出的谷氨酰胺合成酶（GS）在十二烷基硫酸钠-聚丙烯酰胺凝胶上形成一条单一的条带，分子量为44,000。当以羟胺为底物通过测量γ-谷氨酰羟肟酸的形成速率进行测定时，该酶的比活性为179.2 U/mg蛋白质。在锰离子存在下，人脑中GS的相对活性远低于羊脑酶。然而，通过增加ADP浓度对活性的抑制在人酶中比在羊酶中不那么明显。用纯化的酶在兔中制备抗体。双向免疫扩散技术揭示了从人、羊和大鼠脑中分离出的GS之间的交叉反应性，但这些酶在免疫上并不相同。免疫组织化学显示，GS定位于人和大鼠脑星形胶质细胞的细胞质以及肝脏中央周围的肝细胞中。