木瓜脂肪酶催化洛芬类药物的酶促拆分

Carica Papaya Lipase Catalyzed Hydrolytic Resolution of(R,S)-Profen Esters

利用木瓜脂肪酶(CPL)作为催化剂对布洛芬类药物进行手性拆分,建立了底物布洛芬、布洛芬乙酯及其他洛芬类底物的手性检测方法,重点研究了拆分过程中反应温度、有机溶剂、底物结构对拆分效果的影响,并结合动力学分析揭示了木瓜脂肪酶催化手性拆分的分子基础。动力学分析表明对同一底物的不同构型而言,反应速率常数k2S及k2R的差异是木瓜脂肪酶具有手性拆分能力的基础,而不是由于酶对不同构型的底物具有不同的Km值;对一系列化合物的拆分结果表明2-芳基丙酸类手性化合物2位上空间位阻较大的底物比空间位阻小的化合物具有更好的拆分效果。实验表明CPL对洛芬类底物均具有拆分能力,对萘普生的拆分效果最好,经过30h的反应转化率达到49%,反应的对映体选择值(E值)为173。

Carica papaya lipase （CPL） was explored as an effective enantioselective biocatalyst for the hydrolytic resolution of （R,S）-profen esters in water-saturated organic solvents. Firstly, HPLC method was developed for determining the precise conversion and enantiomeric excess of profens and its esters. Kinetic analysis revealed the molecular basis of CPL catalyzed resolution of profen esters. Kinetic analysis of the CPL catalyzed resolution indicated that the enantioselectivity was due to the different reaction rates of the two isomers, not the different Km of the the two isomers. For naprofen the quotient of k2R/k2s was 195 which was approximately equal to the E value 173. Therefore, substrate structure had profound influences on enantioselectivity. Excellent enantioselectivity was found for substrates that contained a bulky substituent at the meta-position of 2-phenyl moiety of the acyl part. For naproxen, the conversion reached up to 49%o after 30 h reaction in n hexane with excellent enantioselectivity（E= 173）.