ALPHA-GALACTOSIDASE FROM ESCHERICHIA-COLI K12
ALPHA-GALACTOSIDASE FROM ESCHERICHIA-COLI K12
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DOI：
10.1016/0304-4165(71)90053-5
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发表时间：
1971-01-01
期刊：
影响因子：
--
通讯作者：
KEPES, A
中科院分区：
文献类型：
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作者：
BURSTEIN, C;KEPES, A
结肠杆菌的生长需要诱导合成α-半乳糖苷渗透酶和α-半乳糖苷酶。整个细菌对显色底物EP-硝基苯基-σ-半乳糖苷的水解依赖于完整的氧化代谢。α-半乳糖苷酶。首次从大肠杆菌中分离得到了一种可溶性酶。在无细胞提取液中，只有在高蛋白浓度下才能观察到α半乳糖苷的水解性，且其活性随稀释度的平方呈指数下降。这种行为的原因被证明是因为，与其他已知的α-半乳糖苷酶不同，E的酶。大肠埃希氏菌需要NAD。要获得最佳活性，该酶还需要Mn2+，高浓度的2-巯基乙醇，以及pH为8.1。用蔗糖梯度沉淀法测定α-半乳糖苷酶活性形式的分子量约为200000。由于该酶的不稳定性，目前还没有实现其纯化。
Growth ofEscherichia colion melibiose requires the induced synthesis of α-galactoside permease and α-galactosidase. Hydrolysis of the chromogenic substratep-nitrophenyl-σ-galactoside by whole bacteria is dependent on intact oxidative metabolism. The α-galactosidase fromE. coliwas isolated for the first time as a soluble enzyme. In cell-free extractsp-nitrophenyl-α-galactoside hydrolisis was observed only at high protein concentrations and the activity decreased exponentially with the square of the dilution. The reason for this behaviour was shown to be that, unlike other known α-galactosidases, the enzyme ofE. colirequires NAD. For optimal activity the enzyme also requires Mn2+, a high concentration of 2-mercaptoethanol, and a pH of 8.1. The approximate molecular weight of the active from of α-galactosidase as determined by sedimentation in a sucrose gradient is 200 000. Due to the instability of the enzyme, its purification has not been achieved.