De Duve 1955 Biochem J

de Duve C, Pressman BC, Gianetto R, Wattiaux R, Appelmans F (1955) Tissue fractionation studies 6. Intracellular distribution patterns of enzymes in rat-liver tissue. Biochem J 60: 604-617.

» PMID:13249955; Open Access

de Duve C, Pressman BC, Gianetto R, Wattiaux R, Appelmans F (1955) Biochem J

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1. The intracellular distribution of a number of enzymes has been investigated in rat liver according to a new fractionation scheme, in which the classical mitochondria are divided into two subfractions. The observed distribution patterns were compared against those of cytochrome oxidase, acid phosphatase and glucose-6-phosphatase, which served as reference enzymes. The data were interpreted in the light of the information furnished by these comparisons and by additional experiments.
2. The distribution patterns of succinate cytochrome c reductase and of rhodanese followed that of cytochrome oxidase, and it was concluded that these systems likewise belong to the mitochondria.
3. The DPNH- and TPNH-cytochrome c reductase activities showed complex distributions, reflecting the existence of two distinct pairs of systems, associated respectively with the mitochondria and the microsomes and differing in their susceptibility to activation by distilled water and inhibition by antimycin A.
4. About 40 % of the total fumarase activity was found in the mitochondria, and the remainder recovered partly in the final supematant, partly in the microsomes, possibly in the latter case as the result of an adsorption artifact.
5. Ribonuclease, deoxyribonuclease, cathepsin and the major part of ,B-glucuronidase showed distributions analogous to that of acid phosphatase. In addition, they resembled this enzyme in being practically unreactive towards their respective substrates in intact preparations, and were released in a parallel fashion from granules subjected to graded activation by a variety of means. These results were taken to indicate that the four hydrolases belong to the, same distinct group of granules previously shown to contain acid phosphatase. The name lysosomes has been proposed for these granules.
6. The microsomes contained a 20 % excess of P-glucuronidase, which differed from the remaining activity by a less acid pH-optimum. A second enzyme species appears to be involved, but the possibility of an interaction between adsorbed enzyme and ribonucleic acids cannot be ruled out.
7. Uricase exhibited a unique distribution, indicating that this enzyme is attached either to the insoluble framework of lysosomes or to a fourth distinct group of granules with the properties of large microsomes.
8. In discussing these results, it is pointed out that many afford direct support to the guiding assumptions that distinct enzymic species have single intracellular locations and that granules of a given class are enzymically homogeneous. Some conflicting evidence has also been brought to light.