College of Life Sciences, Shenzhen University, Shenzhen, Guangdong 518060, China.
J Biotechnol. 2011 Mar 10;152(1-2):30-6. doi: 10.1016/j.jbiotec.2011.01.014. Epub 2011 Jan 22.
Cross-linked tyrosinase aggregates were prepared by precipitating the enzyme with ammonium sulfate and subsequent cross-linking with glutaraldehyde. Both activity and stability of these cross-linked enzyme aggregates (CLEAs) in aqueous solution, organic solvents, and ionic liquids have been investigated. Immobilization effectively improved the stability of the enzyme in aqueous solution against various deactivating conditions such as pH, temperature, denaturants, inhibitors, and organic solvents. The stability of the CLEAs in various organic solvents such as tert-butanol (t(1/2)=326.7h at 40°C) was significantly enhanced relative to that in aqueous solution (t(1/2)=5.5h). The effect of thermodynamic water activity (a(w)) on the CLEA activity in organic media was examined, demonstrating that the enzyme incorporated into CLEAs required an extensive hydration (with an a(w) approaching 1.0) for optimizing its activity. The impact of ionic liquids on the CLEA activity in aqueous solution was also assessed.
通过硫酸铵沉淀和随后用戊二醛交联制备交联的酪氨酸酶聚集体。研究了这些交联酶聚集体（CLEAs）在水溶液、有机溶剂和离子液体中的活性和稳定性。固定化有效地提高了酶在水溶液中的稳定性，使其能够抵抗各种失活条件，如 pH 值、温度、变性剂、抑制剂和有机溶剂。与在水溶液中相比（t(1/2)=5.5h），CLEAs 在各种有机溶剂（如叔丁醇（t(1/2)=326.7h 在 40°C）中的稳定性显著提高。考察了热力学水活度（a(w)）对有机介质中 CLEA 活性的影响，结果表明，固定在 CLEAs 中的酶需要广泛的水合作用（a(w)接近 1.0）以优化其活性。还评估了离子液体对水溶液中 CLEA 活性的影响。
