Caspase酶活力单位定义:参考Chemicon公司One unit is the amount of enzyme that will cleave 1.0 nmol of the colorimetric pNA-substrate per hour at 37 ºC under saturated substrate concentrations。即当底物饱和时,一个Caspase酶活力单位定义为37 ºC 1小时水解pNA底物,产生1nmol游离pNA。根据pNA标准曲线和样品OD值,可计算出Caspase酶活力单位。