中文摘要：

目的建立纳豆激酶（NK）体外活性测定方法，考察影响因素。方法采用对甲基苯磺酰-L-精氨酸甲酯（TAME）作为底物，用变色酸反应显色，在574nm波长处比色测定酶活性。结果NK在0．05—0．25mg／mL浓度范围内具有良好的线性关系；NK在pH8．0，4℃，活性保持最久。结论TAME法测定NK活性操作简便，可较准确测定NK体外活性。温度、pH、某些溶剂对NK的活性有影响。

英文摘要：

Purpose To establish a method for determining Nattokinase activity in vitro, and to investigate the influential factors. Methods Na-4-tosyl-L-arginine methyl ester hydrochloride（TAME）is used as the substrate of Nattokinase, colored by the chromotropic acid, determined in 574 nm by UV. Results Data between the Nattokinase content and absorbance had a better linear relationship in the range 0.05-0.25 mg/mL（ r = 0.998 5）.The Nattokinase activity maintains longer at pH 8.0 and 4℃. Conclusion The TAME method is simple, and it has been applied successfully to determine Nattokinase activity in vitro. Temperature, pH and solvent have influence on Nattokinase activity.