Karube I, Nakamoto Y, Namba K, Suzuki S
Biochim Biophys Acta. 1976 May 13;429(3):975-81. doi: 10.1016/0005-2744(76)90342-9.
(1) Urease (EC 3.5.1.5.) was modified with beta-1-[3,3-dimethyl-6'-nitrospiro-(indoline-2,2'-2H-benzopyrene)] propionic anhydride. Three amino acid residues of urease were modified by the anhydride at a molar ratio of 2000. (2) The activity of modified urease was decreased with ultraviolet irradiation and then restored to the initial activity with visible light irradiation. (3) Modified urease was used to prepare a urease-collagen membrane. The apparent Michaelis constant (Km) of the modified urease-collagen membrane ultraviolet light was identical to that of the membrane under visible light. (4) The optimum pH of the modified urease-collagen membrane was displaced toward lower pH values with ultraviolet irradiation. At higher ionic strength, the pH activity curve of the membrane was displaced toward higher pH values. (5) The thermostability of urease was increased with its modification.
(1) 脲酶（EC 3.5.1.5.）用β-1-[3,3-二甲基-6'-硝基螺-(吲哚啉-2,2'-2H-苯并芘)]丙酸酐进行修饰。脲酶的三个氨基酸残基以2000的摩尔比被该酸酐修饰。(2) 修饰后的脲酶活性经紫外线照射降低，然后经可见光照射恢复到初始活性。(3) 用修饰后的脲酶制备了脲酶-胶原膜。修饰后的脲酶-胶原膜在紫外光下的表观米氏常数（Km）与在可见光下该膜的表观米氏常数相同。(4) 修饰后的脲酶-胶原膜的最适pH值经紫外线照射向较低pH值偏移。在较高离子强度下，该膜的pH-活性曲线向较高pH值偏移。(5) 脲酶经修饰后热稳定性增强。
