A new form of enzymically active jack-bean [Canavalia ensiformis (L.) DC] urease corresponding to an S(20,w) value of 11.8s and a molecular weight of 260000 was investigated. 2. Conversion of 18s urease (EC 3.5.1.5) into the 12s form depends on both low protein concentration and pH. Above pH5.3 urease exists in the 18s form and below pH4.8 in the 12s form; between these two pH values a 12s-18s rapid-equilibrium process is observed. 3. Comparison of the properties of 18s and 12s urease indicated no major differences. 4. A survey of other good urease sources revealed that the 12s form can also be obtained from soya bean (Glycine soja Sieb. and Zucc. cultivar Biloxi) and the bacterium Bacillus pasteurii (Miguel) Migula, but not from watermelon (Citrullus vulgaris Schrad. cultivar Congo). 5. The 12s forms from jack bean and Bacillus pasteurii did not hybridize.
摘要
研究了一种新的具有酶活性的刀豆[Canavalia ensiformis (L.) DC]脲酶，其沉降系数S(20,w)为11.8s，分子量为260000。2. 18s脲酶（EC 3.5.1.5）向12s形式的转化取决于低蛋白浓度和pH值。pH高于5.3时，脲酶以18s形式存在；pH低于4.8时，以12s形式存在；在这两个pH值之间，观察到12s - 18s的快速平衡过程。3. 对18s和12s脲酶性质的比较表明没有重大差异。4. 对其他优质脲酶来源的调查显示，12s形式也可从大豆（Glycine soja Sieb. and Zucc.品种Biloxi）和巴氏芽孢杆菌（Bacillus pasteurii (Miguel) Migula）中获得，但不能从西瓜（Citrullus vulgaris Schrad.品种Congo）中获得。5. 刀豆和巴氏芽孢杆菌的12s形式不能杂交。
