产纤溶酶菌种的鉴定及纤溶酶的分离纯化

为了获得纯纤溶酶并探讨其酶学性质,从广泛收集的豆豉中筛选到一株具有高产纤溶酶能力的菌株,经鉴定为枯草芽孢杆菌.将该菌突变株DC-12N8的发酵液经离心除菌、硫酸铵分级沉淀、DEAE-Sepharose Fast Flow和CM-Sepharose Fast Flow离子交换层析、Sephadex G-75凝胶过滤,获得电泳纯的豆豉纤溶酶,每升发酵液可得到4.5mg活性酶蛋白,每克酶蛋白活力达1.18mol/s,纯度为发酵原液的53.6倍,回收率为11.7%.SDS-聚丙烯酰胺凝胶电泳表明,该酶是单链蛋白质,其分子质量约为28ku.

Identification of Fibrinolytic Enzyme-Producing Strain and Purification of Fibrinolytic Enzyme

In order to obtain pure fibrinolytic enzyme and reveal the enzymatic properties,a fibrinolytic enzyme-producing strain with high fibrinolytic activity was screened form Douchi,a traditional Chinese soybean food and was identified as Bacillus subtilis.The mutant DC-12N8 of the strain was then processed in the following procedure: centrifugal sterilization,fractional sedimentation with ammonium sulfate,DEAE-Sepharose Fast Flow and CM-Sepharose Fast Flow ion-exchange chromatography,Sephadex G-75 gel-filtration.Thus,a kind of fibrinolytic enzyme was purified from Douchi.As compared with the crude enzyme extraction,the specific activity of the purified enzyme increases by 52.6 folds with a recovery of 11.7%,and 4.5 mg of active enzyme protein with an activity of 1.18 mol/s can be obtained from 1 L of fermentation liquid.SDS-PAGE results show that the purified enzyme is a kind of single-train protein with a molecular mass of 28 ku.