Sakamoto N, Kotre A M, Savageau M A
J Bacteriol. 1975 Nov;124(2):775-83. doi: 10.1128/jb.124.2.775-783.1975.
Glutamate dehydrogenase (L-glutamate:NADP+ oxidoreductase [deaminating], EC 1.4.1.4) has been purified from Escherichia coli B/r. The purity of the enzyme preparation has been established by polyacrylamide gel electrophoresis, ultracentrifugation, and gel filtration. A molecular weight of 300,000 +/- 20,000 has been calculated for the enzyme from sedimentation equilibrium measurements. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate and sedimentation equilibrium measurements in guanidine hydrochloride have revealed that glutamate dehydrogenase consists of polypeptide chains with the identical molecular weight of 50,000 +/- 5,000. The results of molecular weight determination lead us to propose that glutamate dehydrogenase is a hexamer of subunits with identical molecular weight. We also have studied the stability and kinetics of purified glutamate dehydrogenase. The enzyme remains active when heat treated or when left at room temperature for several months but is inactivated by freezing. The Michaelis constants of glutamate dehydrogenase are 1,100,640, and 40 muM for ammonia, 2-oxoglutarate, and reduced nicotinamide adenine dinucleotide phosphate, respectively.
谷氨酸脱氢酶（L-谷氨酸：NADP⁺氧化还原酶[脱氨基]，EC 1.4.1.4）已从大肠杆菌B/r中纯化出来。通过聚丙烯酰胺凝胶电泳、超速离心和凝胶过滤确定了酶制剂的纯度。根据沉降平衡测量结果，计算出该酶的分子量为300,000±20,000。十二烷基硫酸钠聚丙烯酰胺凝胶电泳和盐酸胍沉降平衡测量结果表明，谷氨酸脱氢酶由分子量相同的50,000±5,000的多肽链组成。分子量测定结果使我们推测谷氨酸脱氢酶是由分子量相同的亚基组成的六聚体。我们还研究了纯化的谷氨酸脱氢酶的稳定性和动力学。该酶在热处理或室温下放置数月后仍保持活性，但冷冻会使其失活。谷氨酸脱氢酶对氨、2-氧代戊二酸和还原型烟酰胺腺嘌呤二核苷酸磷酸的米氏常数分别为1,100、640和40μM。
