【摘要】 对羊肝中含有的水解穿山龙薯蓣皂苷鼠李糖糖基的穿山龙薯蓣皂苷-α-L-鼠李糖苷酶进行了分离、纯化,并对其动力学特性进行了研究.结果表明,粗酶液经DEAE-Cellulose离子交换层析柱纯化后,其比活提高了19.9倍.在pH=6.8、反应温度为42℃、反应时间为8h和底物浓度为23mmol/L的条件下,该酶达到其最高活力.在10~200mmol/L范围内,Fe3+和Cu2+对酶活力有明显的抑制作用,Mg2+和Zn2+对酶活力有微弱的激活作用,而Ca2+对酶有较强的激活作用.采用SDS-PAGE方法测得酶蛋白分子量为71000.选择穿山龙薯蓣皂苷、人参皂苷Re和芦丁为酶反应底物,进行酶的底物专一性研究发现,穿山龙薯蓣皂苷-α-L-鼠李糖苷酶对其底物具有高度专一性.更多还原

【Abstract】 Dioscorea nipponica is a popular herb in China. It has been wildly used to prevent bronchial and other respiratory infections as well as viral infections to treat rheumatic diseases, to improve cardiovascular conditions, to treat and reduce the risk of heart disease and to protect against cancer. The enzymatic transforming generally improves the bioactivity of natural productions. In this paper, dioscin-α-L-rhamnosidase hydrolyzing α-L-rhamnoside from dioscin was found and purified from sheep liver by means of centrifugation, ammonium sulfate precipitation and ion-exchange chromatography on DEAE-cellulose column, and its partial cha-racteristics were studied. A 19.9-fold purification factor was achieved by DEAE-cellulose column. The enzyme showed the highest activity under the reaction condition of pH=6.8, 42 ℃, 8 h, and 23 mmol/L of substrate concentration. In the concentration range of 10—250 mmol/L, ions Fe3+, Cu2+ strongly inhibited the enzyme, Mg2+ and Zn2+ slightly activated the enzyme, but Ca2+ activated strongly the enzyme. The molecular weight of the enzyme estimated by SDS-PAGE was about 71000. In the comparative examination with rutin-α-L-rhanmosidase, ginsenoside-α-L-rhamnosidase, and α-L-rhamnosidase on the substrates such as dioscin, ginsenoside Re, rutin, it was found that the enzyme has a narrow substrate specificity.更多还原