Stabilization and inhibition of hepatic microsomal glucose-6-P phosphohydrolase (EC 3.1.3.9) by F- requires the presence of Al3+ ions. At millimolar concentrations, reagent grade NaF inhibited glucose-6-P hydrolysis and protected the enzyme against inactivation induced by heat in the presence of 0.025% (w/v) Triton X-100 or by reaction of the catalytic site with the histidine-specific reagent, ...

Rat liver microsomal glucose 6-phosphate phosphohydrolase has been shown to possess two further catalytic activities: the hydrolysis of inorganic pyrophosphate to orthophosphate and a pyrophosphate-glucose phosphotransferase activity. Physiological concentrations of bicarbonate ion (10 to 50 mM) have been found to inhibit all three activities. A detailed kinetic analysis of the nature and exten...

Some tissues contain more than one enzyme exhibiting 'acid-phosphatase' action and the partial separation of such enzymes has been reported, e.g. from rat liver (Goodlad & Mills, 1957; Barka, 1961 a, b) and from Escherichia coli (Rogers & Reithel, 1960). Among the factors that make the interpretation of experimental observations on 'acid-phosphatase activity' difficult are (a) in the earlier wo...

Comparisons have been made of myelinogenic activities in fetal rat brain mixed primary cultures and cultures of isolated oligodendrocytes of comparable age. The specific activities of the sulfatide synthesis, 2',3'-cyclic-nucleotide 3'-phosphohydrolase (2',3'-cyclic-nucleotide 3'-phosphodiesterase, EC 3.1.4.37), and accumulation of myelin basic protein, when expressed per mg of protein, were as...

Two types of extracellular acid phosphatases are synthesized by Aspergillusficuum NRRL 3135: a nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with an optimum pH of 2.0, and an enzyme with restricted specificity, a mesoinositol-hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with an optimum pH of 5.5. Although the pH 5.5 enzyme is termed a phytase, both enzymes hydrolyz...

Glucose-6-phosphatase (glucose-6-phosphohydrolase and its associated phosphotransferase activities) was determined in brain tissue and in several preparations derived from brain tissue. These included purified capillaries and established cell lines of neuronal or glial origin. Since it has been suggested that glucose-6-phosphatase may be involved in sugar transport, the characteristics of that ...

Prostaglandins are known to play a central role in the initiation of labor in humans, and amnionic cells constitute a major source of these compounds. Prostaglandin synthesis and release by amnion cells in response to hormones and ligands takes place after a characteristic 4-5 h lag. However, we report herein that free arachidonic acid (AA), the metabolic precursor of prostaglandins, can be ind...

Paramecium bursaria chlorella virus, a large DNA virus that replicates in unicellular Chlorella-like algae, encodes an RNA triphosphatase which is involved in the synthesis of the RNA cap structure found at the 5' end of the viral mRNAs. The Chlorella virus RNA triphosphatase is the smallest member of the metal-dependent RNA triphosphatases that include enzymes from fungi, DNA viruses, protozoa...