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At least 109 records · Page 6Linked to original sources
PubMed1961

Localization of acid phosphatase activity in hepatic lysosomes by means of electron microscopy.

Samples of liver from untreated rats, from rats infused with unconjugated bilirubin, and from biopsies of human liver were fixed overnight in cold formol-calcium. Frozen sections were stained for acid phosphatase activity by the Gomori lead-glycerophosphate procedure. Small blocks of fixed tissue were also incubated in this medium. These were then treated briefly with osmium tetroxide, dehydrated, and embedded in methacrylate. Thin sections were studied by electron microscopy. The sites of reaction product of acid phosphatase activity as visualized in electron micrographs are consistent with those seen in frozen sections studied by light microscopy. They indicate that the pericanalicular bodies of parenchymatous cells, the large spherical bodies of Kupffer cells, the microbodies appearing after bilirubin infusion and lipofuscin granules belong to the class of cytoplasmic organelles called lysosomes by de Duve.

Acid Phosphatase↗
PubMed1960

Chicken intestinal alkaline phosphatase. I. The kinetics and thermodynamics of reversible inactivation. 2. Reactivation by zinc ions.

Purified chicken intestinal alkaline phosphatase is active at pH 8 to 9, but becomes rapidly inactivated with change of pH to 6 or less. Also, a solution of the inactivated enzyme at pH 4.5 rapidly regains its activity at pH 8. In the range of pH 6 to 8 a solution of purified alkaline phosphatase consists of a mixture of active and inactive enzyme in equilibrium with each other. The rate of inactivation at lower pH and of reactivation at higher pH increases with increase in temperature. Also, the activity at equilibrium in the range of pH 6 to 8 increases with temperature so that a solution equilibrated at higher temperature loses part of its activity on cooling, and vice versa, a rise in temperature shifts the equilibrium toward higher activity. The kinetics of inactivation of the enzyme at lower pH and the reactivation at higher pH is that of a unimolecular reaction. The thermodynamic values for the heat and entropy of the reversible inactivation and reactivation of the enzyme are considerably lower than those observed for the reversible denaturation of proteins. The inactivated enzyme at pH 4 to 6 is rapidly reactivated on addition of Zn ions even at pH 4 to 6. However, zinc ions are unable to replace magnesium ions as cocatalysts for the enzymatic hydrolysis of organic phosphates by alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1962

Alkaline phosphatase content and the effects of prednisolone on mammalian cells in culture.

The alkaline phosphatase content of different tissue culture cell lines has been shown to vary from no detectable activity to high enzyme concentration. Within the epithelial lines studied alkaline phosphatase is either constitutive or inducible. Two epithelial cell strains in which alkaline phosphatase was "absent" could be induced to develop significant amounts of the enzyme when grown in the presence of Delta(1)-hydrocortisone. Phosphate did not repress enzyme induction by prednisolone. Under conditions of deadaptation the induced enzyme was diluted by cell multiplication. The mouse fibroblastic L line and several human fibroblastic lines did not contain alkaline phosphatase when grown under the conditions described nor could they be induced to produce the enzyme when cultivated in medium with prednisolone. Delta(1)-Hydrocortisone has other characteristic effects on established mammalian cell cultures which vary among cell lines. Human epithelial lines show reduction in cell multiplication with increase in mitotic index. The cytoplasm is increased and cell volume is nearly doubled. Mouse fibroblasts show a similar reduction in cell multiplication with a decrease in mitotic index. There is no increase in cell cytoplasm. Human fibroblast strains show no inhibition of multiplication or alteration in total cell protein when grown in medium containing prednisolone. Antisera prepared against "negative" prednisolone-inducible human cell lines and against a positive human line inhibited alkaline phosphatase activity to an equal degree.

Alkaline Phosphatase↗
PubMed1961

Phosphorylphosphatase and oximes.

The effects of pralidoxime iodide, 1,1-trimethylenebis(4-formylpyridinium bromide) dioxime and diacetyl monoxime on the activity of phosphorylphosphatase prepared from pig kidney in vitro have been studied. It was found that these oximes, even at high concentrations, did not affect the activity of the enzyme.

Animals↗
PubMed1962

Cutaneous sensory end organs of some anthropoid apes.

The organized end organs of nerves in glabrous skin of the chimpanzee, orangutan, and gibbon are similar to those of man in form and distribution but are more numerous on the soles of the feet than in man. I found cholinesterase in all the end organs of all these animals and, in the gibbon, alkaline phosphatase as well.

Alkaline Phosphatase↗