Particules subcellulaires dans les tumeurs: I. Distribution intracellulaire de la cytochrome oxydase, la glucose-6-phosphatase, la catalase et plusieurs hydrolases acides dans un hépatome chimique transplantable (hépatome HW)

Abstract

1. 1. The activity of cytochrome oxidase, glucose- 6-phosphatase, catalase and several acid hydrolases has been measured in homogenates of a rat transplantable hepatoma (hepatoma HW) and compared with that found in rat liver. The first three enzymes are much less active in the tumour; on the contrary, acid hydrolases are more active in the hepatoma. 2. 2. The intracellular distribution of these enzymes has been investigated according to a centrifugation scheme similar to that described by de Duve and his co-workers [1]. The homogenates were fractionnated in a nuclear fraction N, a ‘heavy’ and a ‘light’ mitochondrial fraction, M and L, a microsomal fraction P and a soluble fraction S. 3. 3. Cytochrome oxidase and acid hydrolases are chiefly recovered in the mitochondrial fractions; they are the most purified in the ‘light’ one L. Glucose- 6-phosphatase and catalase exhibit a microsomal distribution pattern. 4. 4. Acid hydrolases display the phenomenon of structure-linked latency; they can be activated in the cytoplasmic extract by freezing and thawing, Blendor treatment, hypotonicity and the non-ionic detergent Triton X- 100. Catalase is also found in a latent form in the cytoplasmic extract but cannot be unmasked by hypotonicity nor by freezing and thawing. 5. 5. A comparison has been made between the distributions of the enzymes in the hepatoma HW and in the rat liver. Significant differences have been shown to exist except for the acid hydrolases distribution.