哺乳动物肝匀浆9000克上清液(即肝S9)已广泛用于前致癌物、前致突变物的体外代谢活化。目前,一般认为S9的代谢活性只有在—80℃以下才能保持,因而,迄今所用S9均由各实验室自己制备。这样,实验室间所用S9难于统一,且在制备与贮藏S9时需要较高设备条件,不利于这类工作的推广与普及。尽管不是任何酶类都能用冻干法保存,但是,冻干 Mammalian liver homogenate 9000 g of supernatant (ie, liver S9) has been widely used in the in vitro metabolism of pro-carcinogens, pre-mutants. Currently, it is generally believed that the metabolic activity of S9 is only maintained below -80 ° C, thus the S9 used so far has been prepared by each laboratory itself. In this way, it is difficult to unify the S9 used in the laboratory, and the higher equipment conditions are needed during the preparation and storage of S9, which is not conducive to the promotion and popularization of such work. Although not all enzymes can be lyophilized, they are lyophilized