State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, PR China.
Bioresour Technol. 2012 Jun;114:6-11. doi: 10.1016/j.biortech.2012.03.056. Epub 2012 Mar 28.
The lyophilized Pseudomonas fluorescens cell was an efficient alternative catalyst to enzymes for highly regioselective acylation of a polar nucleoside, 1-β-D-arabinofuranosylcytosine (ara-C). The cells showed an evident solvent dependence in the reaction. Among the tested solvents except for acetonitrile-pyridine, catalytic activity of the cells clearly increased with increasing the polarity of the organic solvents used. Among all the tested solvents both pure and binary, the best results were observed in isopropyl ether-pyridine system, in which the catalyst also showed good thermal and operational stabilities. For the biocataylsis in isopropyl ether-pyridine, the optimal isopropyl ether concentration, water content, acyl donor/ara-C ratio, biocatalyst dosage and reaction temperature were 30% (v/v), 4%, 45, 50mg/mL and 30 °C, respectively, under which the initial rate, yield and 5'-regioselectivity were 2.93 mM/h, 77.1% and 97.3%, respectively. The bacterial cells exhibited comparable 5'-regioselectivity to the expensive immobilized enzyme, which could also have environmental and cost advantages.
冷冻干燥的荧光假单胞菌细胞是一种高效的替代酶催化剂，可用于高度区域选择性酰化极性核苷 1-β-D-阿拉伯呋喃核苷胞嘧啶（ara-C）。该细胞在反应中表现出明显的溶剂依赖性。在除乙腈-吡啶之外的所有测试溶剂中，细胞的催化活性随着所用有机溶剂极性的增加而明显增加。在所有测试的溶剂（无论是纯溶剂还是混合溶剂）中，异丙醚-吡啶体系的效果最佳，该催化剂在该体系中还表现出良好的热稳定性和操作稳定性。在异丙醚-吡啶中的生物催化中，最佳的异丙醚浓度、含水量、酰供体/ara-C 比、生物催化剂用量和反应温度分别为 30%（v/v）、4%、45、50mg/mL 和 30°C，在此条件下，初始速率、产率和 5'-区域选择性分别为 2.93mM/h、77.1%和 97.3%。细菌细胞表现出与昂贵的固定化酶相当的 5'-区域选择性，这也可能具有环境和成本优势。
