抄録
1. Three subfractions of microsomes were obtained by differential centrifugation from the post-mitochondrial supernatant of a 0.88M sucrose homogenate of rabbit liver, and the contents of protein, phospholipid, RNA and iron in these fractions were determined.
2. The distribution of seven enzymes and two hemoproteins among the subfractions were determined, and the results were expressed in terms of specific activity or content per unit weight of phospholipid.
3. It was found that the enzymes concerned in oxidation-reduction reactions (NADH- and NADPH-cytochrome c reductases and aniline hydroxylase as well as hemoproteins (cytochrome b5 and P-450) were most concentrated in the “light” fraction. Glucose-6-phosphatase [EC 3.1.3.9], on the other hand, seemed to occur predominantly in the “heavy” fraction. Among the other hydrolases studied, ATPase [EC 3.6.1.3] and arylsulfatase C [EC 3.1.6.1] were most abundant in microsomes of “intermediate density”, whereas esterase [EC 3.1.1.2] showed a diffuse distribution.
4. These re.ults were taken as preliminary evidence for the presence in the microsomal fraction of several types of vesicles distinguishable biochemically from one another.
