Nonspecific Acid Phosphatase Research Articles

Localization of some phosphatases in yeast.

1. The localization of some phosphatases has been studied in yeast cells that were either fragmented by shaking intact cells with glass beads or by hypotonic or isotonic disruption of protoplasts prepared from intact cells. 2. The non-specific acid phosphatase with optimum activity at pH between 3 and 4 was shown to occur in the cell wall of commercial baker's yeast. As some substrates of the enzyme can only enter that part of the cell volume corresponding to the cell wall and the activity is not increased by freezing and thawing the yeast, it was concluded that all the enzyme is located here. 3. The highly specific α-glycerophosphatase is entirely present in the unstructured cytoplasm of a 17-h culture of Saccharomyces carlsbergensis (No. 74). 4. S. carlsbergensis (No. 74) contains only one non-specific alkaline phosphatase. The distribution depends upon the age of the culture: In a culture aged 17 h two-thirds of the enzyme is bound to particles sedimenting from 3000 × g to 100 000 × g, and one-third is soluble. In a culture aged 24 h 70–85% of the enzyme is found in the soluble fraction, and only a small amount is particle bound.

Studies on a non-specific acid phosphatase from dwarf-bean seedlings

Studies on a non-specific acid phosphatase from dwarf-bean seedlings

The change in shape of the pH-activity curve of acid phosphatase in the liver and spleen of mice after intraperitoneal administration of macromolecular substances

The increase in the activity of acid phosphatase occurring as a result of storage of macromolecular substances in the liver and spleen of mice was studied. Dextran and polyvinylpyrrolidone were injected intraperitoneally in mice of the 0 20 strain. The activity of acid phosphatase was investigated in liver and spleen homogenates between pH 2.9 and pH 7.1. It was shown that in the mice used, there were present three different non-specific acid phosphatases, characterized by different pH optima. As a result of the incorporation of the macromolecular substances, the activity of the entire enzyme complex rises. The increase in activity, however, not being equally large in all the acid phosphatase enzymes. In the liver, after administration of dextran, the activity of the enzyme with an optimum at pH 5.8 showed relatively the largest increase.

Purification and Properties of a Nonspecific Acid Phosphatase from Wheat Germ

While studying the phosphoglyceric acid mutase of wheat germ, we noted marked phosphatase activity when extensively purified mutase preparations were tested with n-3-phosphoglyceric acid and D-Z, 3diphosphoglyceric acid as substrates (1). Since we had found low phosphatase activity for these reagents in many biological materials (2), there was the possibility, previously discussed (l), that the enzymatic hydrolysis of these substrates was a dual function of the purified wheat germ mutase. Further examination, however, showed there was no correlation between phosphatase and mutase activities at several stages of purification, indicating phosphatase contamination of the wheat germ mutase preparations. Additional evidence for the nonidentity of the two enzymatic activities has now been obtained by extensive purification of the phosphatase from wheat germ, by the method presented in this paper. The purified preparations of nonspecific acid phosphatase described in this paper have activities of the same order of magnitude as those of the extensively purified intestinal monoesterase (3) and of the crystalline pyrophosphatase of yeast (4). The best phosphatase preparations are essentially free of P-glycerate mutase activity.

Preparation and some properties of an acid phosphatase from white lupine seedlings

A procedure is described for approximately 1000-fold purification of a nonspecific acid phosphatase from lupine seedlings. The preparation has both general phosphomonoesterase and pyrophosphatase activity. It shows either very little or no activity toward 5′-nucleotides, glucose 1-phosphate, trimetaphosphate, diphenyl phosphate, diphosphopyridine nucleotide, and ribonucleic acid. With p-nitrophenyl phosphate as substrate, the phosphatase shows optimal activity at pH 5.2–5.5. The Michaelis constant for the reaction is 3 × 10 −4 M. Fluoride inhibition of the hydrolysis is noncompetitive. Inactivation upon dilution or purification is prevented by the surface-active agent, Triton X-100. Ethylenediamine tetraacetate increases activity further. Of the cations tested, copper is the most inhibitory; manganese and magnesium are slightly stimulatory. Ethylenediamine tetraacetate prevents the inhibition by copper and augments the stimulation by magnesium. p-Chloromercuribenzoate has negligible effect upon enzymic activity at a saturating concentration of p-nitrophenyl phosphate; it is stimulatory, however, at low substrate concentrations. The differences of plant and animal phosphatases in substrate specificity and the kinetics of inhibition by fluoride may reflect differences in the in vivo functions and mode of action of these enzymes.

The distribution of glucose-6-phosphatase in the liver and kidney of the mouse.

Glucose-6-phosphatase has been demonstrated in frozen sections of mouse liver and kidney. In both organs, the enzyme is present only within parenchymal elements and is absent from stromal tissues. The enzyme is more abundant in the peripheral third of the hepatic lobule than in the inner two-thirds. Within the hepatic cell the enzyme is concentrated about the nuclear membrane. Studies were made of the distribution of the enzyme in the liver in relation to the diurnal cycle but no significant changes in enzyme distribution were observed. In the kidney the enzyme is found in the proximal convoluted tubule, concentrated at the basal pole of the cells, and in portions of the renal glomerulus. The evidence and experimental results are described which indicate that glucose-6-phosphatase is an enzyme distinct from nonspecific acid and alkaline phosphatases and that this enzyme can be so demonstrated histochemically. The presence of this enzyme in the liver and kidney is correlated with the ability of these organs to produce blood-sugar.