蜡状芽孢杆菌Bc-05菌株纤溶酶的酶学性质

对蜡状芽孢杆菌Bc-05茵株的发酵上清液经硫酸铵分级沉淀、DEAE Sepharose Fast Flow阴离子交换层析所获得的纤溶酶进行性质研究.结果表明:经纤维蛋白平板法检测该酶有直接水解纤维蛋白和激活纤溶酶原的双重作用,最适作用温度37℃,最适pH=8.0,在pH=8.0条件下25℃和37℃放置24 h酶活力仍保持77.52%和78.96%,该酶体外对兔血凝块有明显的溶解作用;Ca2+,Mn2+离子对该酶具有激活作用,而Cu2+,Fe3+完全抑制其纤溶活性,PMSF,EDTA和DTT对该酶有抑制作用,说明活性中心含有二硫键、金属离子和丝氨酸;测其N端10个氨基酸序列为NH2-Val-Thr-Pro-Thr-Asn-Ala-Val-Asn-Thr-Gly,与其他生物来源的纤溶酶相比较没有同源性.

Characterization of Fibrinolytic Enzyme from Bacillus cereus Bc-05

Fibrinolytic enzyme was purified from the culture supernatants of Bacillus cereus Bc-05 by centrifuging,precipitation with ammonium sulfate and DEAE Sepharose Fast Flow ion-exchange chromatography.The properties of the enzyme were investigated: The fibrinolytic enzyme from Bacillus cereus Bc-05 hydrolyzed fibrin and it also activated plasminogen to plasmin by the fibrin plate determination.The optimal temperature of the enzyme for hydrolyzing fibrin was 37 ℃.The optimal pH was 8.0,which can preserved 77.52% at 25 ℃ and 78.96% at 37 ℃ relatively in pH 7.0～8.0.In vitro dissolves the thrombus experiment result to indicate the Bc-05 fibrinolytic enzyme has the remarkable dissolution to the rabbit blood clot.Metal ions like Ca2+,Mn2+ activated the enzyme activity,but Cu2+,Fe3+ inhibited it completely.PMSF,EDTA and DTT inhibited the activity of the enzyme which suggested that the activity centre of the enzyme had disulfide bond,metal ions and serine.The first 10 amino acids of the N-terminal sequence of the enzyme were NH2-Val-Thr-Pro-Thr-Asn-Ala-Val-Asn-Thr-Gly and had none homology with that of other fibrinolytic enzyme from biological organism.