根霉12#发酵产生纤溶酶的酶学性质

溶栓疗法是血栓性疾病安全有效的治疗手段,开发新型纤溶酶具有实际应用意义.分离自南方小酒药的根霉12豆粕和麸皮为原料可产生纤溶酶.已采用盐析,疏水层析、离子交换层析和凝胶层析方法对纤溶酶分离提纯.提纯的纤溶酶比活力2143u/mg(尿激酶单位),有直接溶解血栓和激活纤溶酶原的双重溶栓作用,降解纤维蛋白α、β和γ肽链速度快;最适作用温度45℃,适宜作用pH范围6.8～8.8;等电聚焦方法测定该酶等电点8.5±0.1;只分解生色底物N-Succinvl-Ala-Ala-Pro-Phe-pNA,其米氏常数Km为O.23mmol/L,酶转换数Kcat为16.36 s-1;Molish实验和甲苯胺蓝实验均证明该酶为糖蛋白,地衣酚-硫酸法测得该酶含糖量4.70%;EDTA、PMSF、PCMB对该纤溶酶有抑制作用,说明活性中心含有巯基、金属和丝氨酸;N端12个氨基酸序列为NH2-Ser-Val-Ser-Glu-Ile-Gln-Leu-Met-His-Asn-Leu-Gly,与其它生物来源的纤溶酶相比较没有同源性.根霉12#产生的纤溶酶为新型纤溶酶,有希望开发成溶栓药物.

Characteristics of a New Fibrinolytic Enzyme Produced from Rhizopus chinensis 12 #

As a therapeutic agent in thrombosis the fibrinolytic enzymes are of interest and the search for a new enzyme continues. A novel fibrinolytic enzyme was produced from Rhizopus chinensis 120, which was screened from the starter for brewing rice wine in the South of China, by solid fermentation, and purified through ammonium sulfate precipitation, hydrophobic interaction, ionic exchange and gel filtration chromatographies. The purified enzyme hydrolyzed fibrin, it cleaved the alpha-, beta- and gamma-chains of fibrinogen simultaneously, and it also activated plasminogen to plasmin. The enzyme hydrolyzed N-Succinyl-Ala-Ala- Pro-Phe-pNA, and Km was 0.23 mmol/L and Kcat 16.36 s(-1). The optimal temperature of the enzyme for hydrolying fibrin was 45 degrees C, and the optimal pH range of 6.8 - 8.8. The isoelectric point of the enzyme estimated by isoelectric focusing electrophoresis was 8.5 +/- 0.1. The enzyme was a glycoprotein. EDTA, PCMB, PMSF inhibited the activety of the enzyme, and SBTI, Lys, TPCK, Aprotinine had none obvious inhibition, which suggested that the activity centre of the enzyme had hydrosulfuryl, metal and serine. The first 12 amino acids of the N-termimal sequence of the enzyme were NH2-Ser-Val-Ser-Glu-Ile-Gln-Leu-Met-His-Asn-Leu-Gly, and had none homology with that of other fibrinolytic enzyme from other microbes. The novel fibrinolytic enzyme from Rhizopus chinensis 12# has potential to become a therapeutic agent in thrombosis.