Department of Chemistry, Faculty of Sciences and Letters, Yildiz Technical University, Davutpasa Campus, Esenler, 34210 Istanbul, Turkey.
Appl Biochem Biotechnol. 2010 Apr;160(8):2187-97. doi: 10.1007/s12010-009-8812-8.
Multipoint covalent bonding of glucose oxidase (EC 1.1.3.4) to hydrophilic natural polymer dextran and optimization of procedures to obtain, with enhanced temperature and pH stabilities, were studied. Purified enzyme was conjugated with various molecular weight dextrans (17.5, 75, and 188 kD) in a ratio of 20:1, 10:1, 1:1, 1:5, 1:10, 1:15, and 1:20. After 1 h of incubation at pH 7, the activities of purified enzyme and conjugates were determined at different temperatures (25 degrees C, 30 degrees C, 35 degrees C, 40 degrees C, 50 degrees C, 60 degrees C, 70 degrees C, and 80 degrees C), and the results were evaluated for thermal resistance. Increases in temperature from 25 degrees C to 50 degrees C did not change the activities of the conjugates. The conjugate, which was prepared with 75 kDa dextran in a molar ratio of 1:5, showed the highest thermal resistance and even the activity still remains at 80 degrees C at pH 7.0. This conjugate also displayed activity in a wide pH range (pH 4.0-7.0) at high temperatures. Conjugate, which was synthesized with 75 kDa dextran in a molar ratio of 1:5, appears to be feasible and useful for biotechnological applications.
研究了葡萄糖氧化酶（EC 1.1.3.4）与亲水性天然聚合物葡聚糖的多点共价结合，并优化了获得具有增强的温度和 pH 稳定性的方法。将纯化的酶与各种分子量的葡聚糖（17.5、75 和 188 kD）以 20:1、10:1、1:1、1:5、1:10、1:15 和 1:20 的比例进行偶联。在 pH 7 下孵育 1 小时后，在不同温度（25°C、30°C、35°C、40°C、50°C、60°C、70°C 和 80°C）下测定纯化酶和缀合物的活性，并评估其耐热性。从 25°C 升高到 50°C 不会改变缀合物的活性。以摩尔比 1:5 用 75 kDa 葡聚糖制备的缀合物具有最高的耐热性，即使在 pH 7.0 下 80°C 时仍保持活性。该缀合物在高温下还在较宽的 pH 范围内（pH 4.0-7.0）具有活性。以摩尔比 1:5 用 75 kDa 葡聚糖合成的缀合物似乎是可行且适用于生物技术应用的。
