Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphatidate phosphatase (phosphatidate phosphohydrolase, EC 3.1.3.4) was present at very high specific activity in the soluble fraction of isolated rat adipocytes. Using phosphatidate in aqueous dispersion 90% of its hydrolysis depended on the presence of Mg2+. Mg2+ appeared to almost saturate the enzyme at 20-40 mM with no indication of an optimum. The substrate concentration was optimum at 1.2 mM and the pH at 6.8. Initial rates were linear for only 4-5 min at optimum conditions. Increasing inhibition occurred at high phosphatidate concentrations. At optimum conditions acid or alkaline phosphatase activity was not measurable. The Mg2+-dependent activity was enhanced by 3-sn-phophatidylcholine and inhibited by albumin, 3-sn-phosphatidyletanolamine, 3-sn-phosphatidylinositol, diacylglycerol, oleoyl-CoA, and oleate. Oleoyl-CoA was the most potent "effector". Fasting for 24, 48 and 72 h decreased the activity both relative to protein and to DNA. The activity thus decreased to about one-third of that of the fed rat during 72 h of fasting. The effects of Mg2+, various lipids, and fasting may indicate that some form of control of glyceride synthesis can be exerted through the soluble phosphatidate phosphatase.
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PMID:Soluble rat adipocyte phosphatidate phosphatase activity: characterization and effects of fasting and various lipids. 1 49

Lung surfactant, a lipid-protein complex purified from dog lungs, contains a highly active phosphomonoesterase associated with it. This phosphatase is quite specific for the hydrolysis of phosphatidic acid and 1-acyl-2-lysophosphatidic acid. The enzyme possesses many of the characteristics of the microsomal enzyme, phosphatidate phosphohydrolase (EC 3.1.3.4). In addition, we have shown that this enzyme will also convert phosphatidylglycerol phosphate [1-(3-sn-phosphatidyl)-sn-glycerol-1-P] to phosphatidylglycerol [1-(3-sn-phosphatidyl)-sn-glycerol] and Pi. The phosphatidylglycerol phosphate was made available to the surfactant enzyme in a coupled assay by hydrolysis of cardiolipin [1-(3-sn-phosphatidyl)-3-(3-sn-phosphatidyl)-sn-glycerol] by stereospecific cleavage with phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Bacillus cereus. This enzyme has been previously shown to generate the naturally occurring isomer of phosphatidylglycerol phosphate because it has specificity for the 3-(3-sn-phosphatidyl) group of cardiolipin. Other properties of the surfactant enzyme are discussed in relation to its presence in lung surface active material.
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PMID:Properties of an acid phosphatase in pulmonary surfactant. 692 79

One of the primary products of [4,5-3H]sphinganine phosphate, added to fibroblast cultures, is sphinganine [Van Veldhoven and Mannaerts (1994) Biochem. J. 299, 597-601], implicating the physiological action of (a) hitherto unknown phosphatase(s). We have now further characterized this activity in rat liver. In homogenates, the dephosphorylation appeared to be catalysed by multiple enzymes. A low-affinity system was active at acidic pH, whereas at physiological pH values hydrolysis was carried out by a high-affinity enzyme. The latter was sensitive to Zn2+ and detergents and possessed a pH optimum of 7.5. Upon cell fractionation the major portion of the high-affinity activity was recovered in the nuclear and microsomal fractions. Further separation of the microsomal fraction showed an association predominantly with vesicles derived from the plasma membrane. Likewise, when plasma membranes were prepared from the nuclear fraction, the high-affinity phosphatase co-purified with the plasma membrane markers. From the differential effects of bivalent cations, chelators, water-soluble and amphiphilic phosphate esters, detergents and other compounds, it could be concluded that the plasma membrane-associated sphinganine-phosphatase activity is not due to alkaline phosphatase, dolichol-phosphatase, the N-ethylmaleimide-insensitive phosphatidate phosphatase or ceramide-phosphatase. The dephosphorylation observed at acidic pH in homogenates appeared also to be enriched in purified plasma membranes and might represent a side-activity of ceramide-phosphatase. We speculate that the high-affinity phosphatase, which is especially active in neuronal tissues, plays a role in the attenuation of bioactive phosphorylated sphingoid bases such as sphingenine phosphate, and propose to name it sphingosine-phosphatase.
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PMID:Identification and subcellular localization of sphinganine-phosphatases in rat liver. 757 45