【作者】 贺莹；

【导师】 高静；

【作者基本信息】 河北工业大学 ， 生物化工， 2006， 硕士

【摘要】 扁桃酸即α-羟基苯乙酸,其旋光性的单体R（-）-扁桃酸及其衍生物是一类重要的手性砌块,是许多药物如半合成青霉素、头孢菌素等制备的重要中间体,被广泛应用于药物合成及立体化学的研究领域。酶具有高度地立体选择性,广泛地底物特异性等优点,因此非水体系中酶法拆分在手性药物的合成与纯化中将会有突出的贡献。 本文对在非水体系中,利用脂肪酶催化水解扁桃酸乙酯外消旋混合物拆分R（-）-扁桃酸进行了初步的研究。筛选出脂肪酶N435作为催化剂,叔丁醇作为溶剂。确定了最适的反应条件:脂肪酶N435浓度为2.5g·L^-1,RS（（?））-扁桃酸乙酯浓度为0.250mol·L^-1,水:RS（（?））-扁桃酸乙酯的摩尔比为5:1,反应温度为40℃,摇床转速为200r·min^-1,反应时间为24h。在此条件下,R（-）-扁桃酸乙酯的最终转化率为41.6%,对映体过量百分率达84.0%。 本文对酶浓、底物浓度、摇床转速和反应温度四个主要影响因素进行了正交实验分析,得到的最优反应条件为:酶浓为3.0g·L^-1,底物浓度为0.050mol·L^-1,反应温度为50℃,摇床转速为200r·min^-1,反应24h后转化率达45.9%,对映体过量百分率达85.2%。 考察了底物R（-）-扁桃酸乙酯和产物R（-）-扁桃酸对反应的抑制作用,确定反应符合米氏方程,属于双底物抑制的顺序机制。在此基础上运用拟稳态法,建立了该反应的动力学模型,动力学参数拟合结果为:V_max=186μmol·（L·min·g enzyme）^-1;K_mA=0.0434mol·（L·genzyme）^-1;K_mB=2.67mol·（L·g enzyme）^-1;K_ia=0.0126mol·（L·g enzyme）^-1;K_iq=0.0144mol·（L·g enzyme）^-1。通过验证,所建立的动力学模型与实验数据吻合的很好,证明该动力学模型是正确的。更多还原

【Abstract】 Enantiomers of mandelic acid which is also named a-hydroxy styrene, and their derivatives are valuable chemicals which is used as a precursor for the manufacture of semi-synthetic penicillin and cephalosporin. They have been utilized extensively for synthetic purposes as well as stereo-chemical investigations. Enzyme catalysis will get prominence in chiral drug synthesis and purification for their high enantio-selectivity and wide substrate specificity.It was studied that lipase catalyses optical resolution of R-mandelic acid via RS-ethyl mandelate in non-aqueous media. Lipase N435 was screened as catalyst, and tert-butanol as solvent. When lipase N435 was 2.5 g·L^-1, RS-ethyl mandelate was 0.250 mol·L^-1, water to RS-ethyl mandelate was 5:1, temperature was 40℃, the speed of agitation was 200 r/min, the R-ethyl mandelate conversion will reach to 41.6 %, and e.e was 84.0 % after 24 h.Enzyme concentration, RS（-|+）-ethyl mandelate concentration, speed of agitation andtemperature were determined with cross-over method. The best results were: N435 was 3.0 g.L^-1, RS-ethyl mandelate was 0.050 mol·L^-1, temperature was 50 °C, and the speed of agitation was 200 r/min, the R-ethyl mandelate conversion will reach to 45.9 %, and e.e was 85.2 % after 24 h. The reaction rate could be described in terms of the Michaelis-Menten equation with the ordered bi-bi mechanism. Studied inhibition by substrate and product, the kinetic model which follows quasi-steady state was built. The values of the apparent kinetic parameters were computed as : V_max= 186 μmol·（L·min·g enzyme）^-1;K_mA= 0.0434 mol（Lg enzyme）¹;K_mB = 2.67 mol-（L-g enzyme）^-1;K_ia= 0.0126 mol·（L·g enzyme）^-1;K_iq= 0.0144 mol·（L·g enzyme）^-1. Model results were found to fit the initial rate data very well.更多还原