DISTRIBUTION AND PROPERTIES OF INTRACELLULAR ALKALINE PHOSPHATASES

Abstract

Histochemical tests for alkaline phosphatase demonstrated that in the salivary gland chromosomes of Drosophila larvae, the enzymatic activity was localized in the chromosomal regions which are Feulgen positive, and thus correspond to the regions containing large concs, of desoxyribose nucleic acid. With mouse tissues, using different naturally occurring substances as substrates, there were obtained 3 types of phosphatase reaction based on the location of the enzyme activity within the cell. When Na glycerophosphate and nucleotides were used as substrates, a general reaction occurred in cytoplasm and nucleus. No enzymatic reaction occurred with polymerized desoxyribose nucleic acid as sub- strate; but a definite reaction was indicated in the nucleus when partially depolymerized desoxyribose nucleic acid was used. When ribose nucleic acid was used, the reaction was mainly cytoplasmic. The 2 latter reactions are located in the same cellular regions as their specific substrates. These reactions are considered to be due to a nuclear phosphodi-esterase, a cytoplasmic phosphodiesterase, and a phospho-monoesterase.