【摘要】 利用溴麝香草酚蓝作为反应指示剂,快速地筛选到产对映选择性脂肪酶菌株GXU33(Geotrichumsp.),此酶能够拆分外消旋扁桃酸甲酯产生(S)-扁桃酸。此菌株最适生长、产酶条件为橄榄油10 g/L,酵母粉5 g/L,Na2HPO4.12H2O3.5 g/L,KH2PO41.0 g/L,MgSO4.7H2O0.2g/L,pH7.0,28℃,200 r/min。PMSF和蛋白酶K对菌株生长没有影响,PMSF显著抑制酶活,蛋白酶K具有保护酶活力的作用。该脂肪酶最适作用pH为7.5,最适作用温度为30℃;Ca2+,Mg2+,Zn2+不同程度提高酶活性,Cu2+,Co2+,Mn2+,Fe2+,Fe3+严重抑制酶活性。当以5%DM-SO为助剂,消旋扁桃酸甲酯20 mg,GXU33脂肪酶1500 U,25 mmol/L磷酸钠缓冲液(pH7.5)加至总体积2 mL,32℃,100 r/min,反应8h,得到最佳拆分效果:转化率为44.8%,(S)-扁桃酸对映过量值为83.5%。更多还原

【Abstract】 Geotrichum sp.GXU33 producing lipase for enantioselective resolution(R,S)-methyl mandelate to(S)-mandelic acid was rapidly isolated by using pH indicator of bromothymol blue as reaction indicator.The optimal conditions for growth and lipase production were olive oil 10 g/L,yeast extract 5 g/L,Na2HPO4·12H2O 3.5 g/L,KH2PO4 1.0 g/L,MgSO4·7H2O 0.2 g/L,pH 7.0,28 ℃,200 r/min.PMSF and proteinase K have no effect on the strain growth,but PMSF badly inhibited lipase activity.Proteinase K 500 μg/mL protected the lipase.The optimal pH and temperature of the lipase were 7.5 and 30 ℃,respectively.The enzyme was stimulated by Ca2+,Mg2+ ,Zn2+ and strongly inhibited by Cu2+,Co2+,Mn2+,Fe2+ and Fe3+.The best resolution was obtained with conversion of 44.8% and ee of 83.5% in the reactions including 5% DMSO,(R,S)-methyl mandelate 20 mg,GXU33 lipase 1500 U,25 mmol/L phosphate buffer(pH 7.5) added to the final volume of 2 mL,100 r/min for 8h.更多还原