耐热乳糖酶的纯化及理化性质研究

Studies on the Purification and Physical-chemical Properties of Thermostable Lactase

目的:对从栖热菌(Thermussp.A3)中分离得到的耐热乳糖酶进行纯化及部分理化性质的研究。方法:采用聚丙烯酰胺凝胶盘状电泳分离耐热乳糖酶,用5-溴-4-氯-3-吲哚-β-D半乳糖苷(x-gal)进行酶染显色,切下单一电泳带进行回收;分别用SDS-聚丙烯酰胺凝胶电泳法(SDS-PAGE)及非变性孔径梯度聚丙烯酰胺凝胶电泳法测定其分子质量,用聚丙烯酰胺管状等电聚焦电泳法测其等电点。结果表明:用SDS-PAGE法及梯度电泳法测定该耐热乳糖酶的分子质量分别为51.1kD和65.6kD;用等电聚焦电泳法测得其等电点约为7.2。结论:从栖热菌中提取的耐热乳糖酶的理化性质不同于其它来源的乳糖酶。

Objective:To purify and partially physical-chemical properties of thermostable lactase from the strain of thermus sp A3 were studied in this paper. Methods:Thermostable lactase was separated by disc polyacrylamide gel electrophoresis, the lactase was stained with x-gal,and recovered from single electrophoretic strip. Its molecular mass was measured by SDS -polyacrylamide gel electrophoresis(SDS-PAGE)and native pore-gradient polyacrylamide gel electrophoresis respectively. Its isoelectric point(pI)was determined by isoelectric focusing tube electrophoresis. Results:The purity examined by SDS-PAGE showed as a single band. Its molecular mass measured by SDS-PAGE and native pore-gradient polyacrylamide gel electrophoresis was 51.1 kD and 65.6 kD respectively. Its pI was about 7.2. Conclusion:The thermostable lactase from strain of thermus sp A3 was different from lactases from other microorganism.