嗜酸乳杆菌胆盐水解酶的分离纯化及酶学性质

Purification and Enzymatic Properties of Bile Salt Hydrolase Produced by Lactobacillus acidophilus

对嗜酸乳杆菌La-XH1产生的胆盐水解酶进行分离纯化,并对其部分酶学性质进行研究。结果表明:嗜酸乳杆菌La-XH1胆盐水解酶的粗酶液经硫酸铵沉淀、DEAE-Sepharose CL-6B柱层析后的酶比活力分别为47.82 U/mg和115.85 U/mg,纯化倍数分别为4.46倍和10.82倍,酶的回收率分别为59.89%和25.11%;通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecylsulfate polyacrylamide gel electrophoresis,SDS-PAGE)电泳分析,该酶的分子质量约为43 kD,最适温度为40℃,最适pH值为6.0,Fe3+、Ca2+、Mg2+、Mn2+、Zn2+对该酶有激活作用,其中Fe3+的激活作用最强,Na+、K+对该酶几乎无作用,而Cu2+、Ba2+对该酶有很强的抑制作用。

Bile salt hydrolase （BSH） produced by Lactobacillus acidophilus La-XH1 is able to hydrolyze conjugated bile salts into free cholic acid, which can co-precipitated with cholesterol at low pH, thus leading to the removal of cholesterol. In this study, the bile salt hydrolase was separated and purified, and some of its enzymatic properties were studied. Results showed that the specific activity of crude extract and purified enzyme by ammonium sulfate precipitation and DEAE- Sepharose CL-6B column chromatography was 47.82 and 115.85 U/rag, respectively, which corresponded to purification folds of 4.46 and 10.82 and recovery rates of 59.89% and 25.11%, respectively. The molecular weight of the purified enzyme was about 43 kD by SDS-PAGE. Its optimum temperature and pH were 40 ℃ and 6.0, respectively. Fe3＋, Ca2＋, Mg2＋, Mn2＋ and Zn2＋ had activation effect on the enzyme, especially Fe3＋. Na＋ and K＋ had no effect, but Cu2＋ and Ba2＋ had strong inhibitory effects on it.