人类血小板蛋白酶活性研究。

SOLUBILIZED PROTEIN DERIVED FROM HUMAN PLATELETS WAS FRACTIONATED BY DEAE CELLULOSE COLUMN CHROMATOGRAPHY AND ANALYZED FOR PROTEASE ACTIVITY USING THREE SUBSTRATES

denatured bovine hemoglobin, alpha casein, and purified plasminogen-free human fibrinogen. A protein fraction was found with proteolytic activity which was heat labile and not attributable to plasmin. The activity was not potentiated by cysteine or inhibited by iodoacetamide. Studies of pH optima indicated a broad range of enzyme activity with peaks in both the acid and alkaline region. Cathepsin A activity was detected in the platelet protease fraction by hydrolysis of the synthetic substrate N-carbobenzoxy-alpha-L-glutamyl-L-tyrosine. Similar proteolytic activity was found when the proteins derived from isolated platelet granules were examined. The results indicate that human platelets possess potent intracellular proteolytic enzymes. The relationship of this proteolytic activity to the hemostatic process is discussed.

从人血小板中提取的可溶性蛋白质通过二乙氨基乙基纤维素柱色谱进行分级分离，并使用三种底物对蛋白酶活性进行分析：变性牛血红蛋白、α-酪蛋白和纯化的无纤溶酶原人纤维蛋白原。发现一种具有蛋白水解活性的蛋白质组分，其对热不稳定且不归因于纤溶酶。该活性不受半胱氨酸增强，也不受碘乙酰胺抑制。最适pH研究表明酶活性范围广泛，在酸性和碱性区域均有峰值。通过合成底物N-苄氧羰基-α-L-谷氨酰-L-酪氨酸的水解，在血小板蛋白酶组分中检测到组织蛋白酶A活性。当检查从分离的血小板颗粒中获得的蛋白质时，发现了类似的蛋白水解活性。结果表明人血小板拥有强大的细胞内蛋白酶。讨论了这种蛋白水解活性与止血过程的关系。