DEPUE R H, MOAT A G
J Bacteriol. 1961 Sep;82(3):383-6. doi: 10.1128/jb.82.3.383-386.1961.
Depue, Robert H. (Hahnemann Medical College, Philadelphia), and Albert G. Moat. Factors affecting aspartase activity. J. Bacteriol. 82:383-386. 1961.-Cells of Escherichia coli grown in a glucose-mineral salts medium contain about one-fifth the amount of aspartase activity observed in cells grown in a yeast extract-peptone medium. The aspartase activity of the cells grown in glucose-salts medium would appear to be too low to provide a mechanism for synthesis of amino groups. Aspartase was purified approximately eightfold by ammonium sulfate precipitation and column chromatography of cell-free extracts. The purified preparation was specific for l-aspartic acid and contained no fumarase activity. A divalent metal ion requirement was demonstrated, this requirement being satisfied by cobaltous or manganous ions. The enzyme activity was found to be dependent upon free sulfhydryl groups. Biotin did not appear to be directly involved in the aspartase reaction since high concentrations of avidin did not alter the reaction rate. The Michaelis constant for aspartase with aspartic acid as substrate was determined to be 0.033 m.
德普伊，罗伯特·H.（费城哈内曼医学院），以及阿尔伯特·G.莫特。影响天冬氨酸酶活性的因素。《细菌学杂志》82:383 - 386。1961年。——在葡萄糖 - 矿物盐培养基中生长的大肠杆菌细胞所含天冬氨酸酶活性约为在酵母提取物 - 蛋白胨培养基中生长的细胞所观察到活性的五分之一。在葡萄糖 - 盐培养基中生长的细胞的天冬氨酸酶活性似乎过低，无法提供一种合成氨基的机制。通过硫酸铵沉淀和对无细胞提取物进行柱色谱法，天冬氨酸酶被纯化了约八倍。纯化后的制剂对L - 天冬氨酸具有特异性，且不含有延胡索酸酶活性。已证明需要二价金属离子，钴离子或锰离子可满足这一需求。发现酶活性依赖于游离巯基。生物素似乎未直接参与天冬氨酸酶反应，因为高浓度的抗生物素蛋白不会改变反应速率。以天冬氨酸为底物时，天冬氨酸酶的米氏常数被确定为0.033 m。
