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

Primary mineral formation in woven bone has been associated with the production of extracellular matrix vesicles. Previous studies have demonstrated an increase in phospholipid: Ca:Pi complexes (CPLX) immediately prior to hydroxyapatite formation. Since matrix vesicles are enriched in phosphatidylserine and PS is the major phospholipid in CPLX, the present study examined whether the morphologic appearance of matrix vesicles and initial formation of crystals within them could be correlated to changes in their phospholipid composition and metabolism. Ablation of the tibial marrow in rats was used as the model since this procedure induces endosteal repair with primary mineralization. The morphologic appearance of the matrix vesicles was assessed by morphometric analysis at the electron microscopic level. Matrix vesicles were divided into 4 categories: empty, amorphic, crystal, and rupture. There was time dependent decrease in the number of empty and amorphic matrix vesicles which correlated with an increase in crystal and rupture type. Distance from the calcification front decreased as more rupture-type vesicles were noted. In a parallel set of experiments, matrix vesicle-enriched membranes (MVEM) were isolated from homogenates of endosteal tissue removed from the treated tibia as well as from the contralateral control. There was an increase at 6 days in MVEM alkaline phosphatase and phospholipase A2 specific activities in both limbs, the magnitude of response being significantly greater in the treated legs. The phospholipid composition of the MVEM changed with time. SPH was highest at day 3, PS was detectable only in day 6 and 14 samples, and PC exhibited a time dependent decrease.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Changes in extracellular matrix vesicles during healing of rat tibial bone: a morphometric and biochemical study. 273 56

The amount and composition of lysophosphatidate present in different rat tissues have been estimated by an internal standard method in which a synthetic unnatural isomer (1-heptadecanoyl-rac-glycerol-3-phosphate) was added to the total lipid extracts, and the fatty acid composition of purified lysophosphatidate was determined. Lipids from tissues were extracted under acidic conditions, and the lysophosphatidate was purified by solvent partitions followed by thin-layer chromatography in multiple solvent systems. The purified lipid was shown to be 1-acyl-sn-glycerol-3-phosphate by chromatographic and chemical analysis, by its resistance to hydrolysis when treated with phospholipase A2 and also by its complete conversion to 1-acyl-sn-glycerol when treated with alkaline phosphatase. The fatty acid constituents of this lipid were determined by gas-liquid chromatography of the derived methyl esters. The concentrations (nmol/g of tissue) of lysophosphatidate in various tissues were: 86.2 +/- 4.2 in brain, 60.3 +/- 6.3 in liver, 46.4 +/- 6.5 in kidney, 30.6 +/- 5.0 in testis, 22.3 in heart and 19.3 in lung. Mostly (80%) saturated fatty acids were found to be present in this lyso lipid. A significantly high level of stearic acid was present in this lipid from all the tissues (50-60% in liver, kidney, brain and testis, and about 40% in heart and lung) compared to palmitic acid (10-15% in liver, kidney and brain and 25-30% in testis, heart and lung). The fatty acid compositions of phosphatidic acid, the putative product of lysophosphatidate acylation, from different tissues were also determined and palmitate was found to be the major saturated fatty acid.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quantification, characterization and fatty acid composition of lysophosphatidic acid in different rat tissues. 275 10

Bungarus candidus venom exhibited high hyaluronidase, acetylcholinesterase and phospholipase A activities; low proteinase, 5'-nucleotidase, alkaline phosphomonoesterase and phosphodiesterase activities and moderately high L-amino acid oxidase activity. SP-Sephadex C-50 ion exchange chromatographic fractionation of the venom and Sephadex G-50 chromatography of the major lethal venom fractions indicate that the venom contains at least two highly lethal, basic phospholipases A with LD50 (i.v.) values of 0.02 micrograms/g (F6A) and 0.18 micrograms/g (F4A), respectively; as well as two polypeptide toxins with LD50 (i.v.) values of 0.17 micrograms/g and 0.83 micrograms/g, respectively. The major lethal toxin is the basic lethal phospholipase A, F6A, which accounts for approximately 13% of the venom protein and has a mol. wt of 21,000.
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PMID:The lethal and biochemical properties of Bungarus candidus (Malayan krait) venom and venom fractions. 279 37

Phospholipase A2 activity is raised in non-lesional psoriatic epidermis compared with normal epidermis. It has been shown that the activity of this enzyme is controlled by an inhibitory protein the inhibitory effect of which is increased by dephosphorylation. Treatment of epidermal extracts with alkaline phosphatase reduced the phospholipase A2 activity, both in normal and in lesion-free psoriatic epidermis. Inclusion of pyrophosphate, a protein phosphatase inhibitor, in the homogenizing medium caused the activity of phospholipase A2 in epidermal extracts from normal and lesion-free epidermis to be raised to the same high level. These results are consistent with the hypothesis that the raised phospholipase A2 activity in psoriatic epidermis is due to hyperphosphorylation of an endogenous inhibitor as a result of defective control of a phosphorylation/dephosphorylation mechanism. The relevance of these findings to other work is discussed.
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PMID:Modulation of phospholipase A2 activity in extracts of lesion-free psoriatic epidermis by alkaline phosphatase and a protein phosphatase inhibitor. 283 3

1. The L-amino acid oxidase, hyaluronidase, alkaline phosphomonoesterase, protease, phosphodiesterase, acetylcholinesterase, phospholipase A and 5'-nucleotidase activities of 47 samples of venoms from all the six species of cobra (Naja), including five subspecies of Naja naja, were examined. 2. The results demonstrated interspecific differences in the venom contents of phospholipase A, acetylcholinesterase, hyaluronidase and phosphodiesterase. These differences in venom enzyme contents can be used for the differentiation of species of the genus Naja. 3. Thus, our results revealed a correlation between the enzyme composition of venom and the taxonomic status of the snake at the species level for the genus Naja.
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PMID:A comparative study of cobra (Naja) venom enzymes. 285 66

The phospholipase A2 inhibitory activity of a 38 kDa K+-sensitive actin gelation factor in a murine leukemia cell line (M1) was examined. A specific antibody against 38 kDa protein was found to cross-react with 37 kDa protein (lipocortin) in rat peritoneal exudates. Although the native 38 kDa protein from M1 cells did not block phospholipase A2 activity, pretreatment with alkaline phosphatase produced a form that did inhibit this enzyme. However, a purified 38 kDa protein from differentiated M1 cells blocked phospholipase A2 activity without pretreatment with alkaline phosphatase. Phospholipase A2 inhibitory activity of the 38 kDa protein was not altered by addition of actin. These findings suggest that the phospholipase A2 inhibitory of our 38 kDa protein was induced during differentiation. We also proposed that our 38 kDa protein has the same epitope as lipocortin.
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PMID:Changes of phospholipase A2 inhibitory activity in the K+-sensitive actin gelation factor during the differentiation of myeloid leukemia cells. 295 92

Brush-border membranes were isolated from rabbit small intestine by procedures involving precipitation of undesired membranes with either 10 mM MgCl2 or 10 mM CaCl2. The membranes were compared on the basis of marker enzyme content and lipid composition. Ca2+-prepared membranes displayed a greater enrichment of alkaline phosphatase and sucrase activity compared to homogenate than did the Mg2+-prepared membranes. The former also displayed an impoverishment of (Na+ + K+)-ATPase activity, the specific activity of which increased several-fold in Mg2+-prepared membranes. Membranes prepared with Ca2+ were characterized by a lower phosphoacylglycerol-protein ratio and a higher phosphatidylethanolamine-phosphatidylcholine ratio. Although lysophosphoacylglycerols accounted for about 6% of the total phospholipids in these membranes compared to 2% in Mg2+-prepared membranes, the free fatty acid content was similar in both types of membranes. It was concluded that Ca2+ prepared membranes were less contaminated by basolateral membranes than were Mg2+-prepared membranes and the use of Ca2+ did not notably enhance degradation of endogenous lipids by brush-border membrane phospholipase A.
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PMID:A comparison of brush-border membranes prepared from rabbit small intestine by procedures involving Ca2+ and Mg2+ precipitation. 300 39

Testosterone-treated calf thymocytes produce increased amounts of proteins, termed lipokinins, that stimulate phospholipase A2 from snake venom and mammalian tissue. The induction of these proteins by testosterone is blocked by cycloheximide and, thus, requires new protein synthesis. These proteins activate phospholipase A2 stoichiometrically. They are inactivated by boiling, trypsin or alkaline phosphatase but not by deoxyribonuclease or ribonuclease. Lipokinins significantly repair the failure of masculinization in the Tfm mouse with an X-linked deficiency of androgen-receptor. Thus, the post-receptor effects of testosterone on embryonic genitalia may be mediated through stimulation of phospholipase A2 by lipokinins. Moreover, lipokinins may be involved as stimulators of the arachidonic acid cascade, as lipocortins are inhibitors.
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PMID:John Lattimer lecture. Lipokinins: novel phospholipase A2 activators mediate testosterone effects on embryonic genitalia. 318 94

The toxic and biological activities of four samples of Trimeresurus purpureomaculatus venom were examined. The lethality, protein composition and biological activities of the four venom samples were similar. Three of the venom samples had LD50 (i.v.) values of 0.9 micrograms/g while the fourth had a lower LD50 (i.v.) of 0.45 micrograms/g. All four venom samples exhibited hemorrhagic, edema-inducing, anticoagulant and thrombin-like activities as well as the usual enzymes found in crotalid venoms. DEAE-Sephacel ion exchange chromatographic fractionation of the venom yielded 10 protein fractions. Only two fractions (fractions A and F) were lethal to mice; the major lethal fraction being fraction F. This fraction had an LD50 (i.v.) of 0.2 micrograms/g and exhibited hemorrhagic, edema-inducing and thrombin-like activity. It also exhibited phospholipase A, arginine ester hydrolase, arginine amidase, protease, 5'-nucleotidase, acetylcholinesterase and alkaline phosphomonoesterase activities. The lethal potency of fraction F is potentiated by fraction G, which exhibited anticoagulant activity as well as hemorrhagic, edema-inducing and enzymatic activities. Fractions F plus G account for almost 100% of the lethal potency of the venom.
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PMID:Biological properties of Trimeresurus purpureomaculatus (shore pit viper) venom and its fractions. 324 58

Third passage confluent cultures of cartilage cells, initially derived from the growth zone (GC) and resting zone (RC) of rat costochondral cartilage, were incubated with either 10(-11)-10(-8) M 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] or 10(-9)-10(-6) M 24,25-(OH)2D3. Plasma membranes and extracellular matrix vesicles were isolated, and specific activities of phospholipase A2 and alkaline phosphatase were determined. The results demonstrate that the response to hormone is both cell and membrane specific. 1,25-(OH)2D3 produces an increase in GC matrix vesicle alkaline phosphatase and phospholipase A2 specific activities at 10(-9) and 10(-8) M, but has no effect on these enzyme activities in RC membranes. RC cultured in 24,25-(OH)2D3 exhibit increased matrix vesicle alkaline phosphatase but decreased phospholipase A2 activities at 10(-7) and 10(-6) M hormone. No effect on the RC plasma membrane enzymes or on GC plasma membrane or matrix vesicle enzymes was observed. The data suggest that changes in membrane fluidity due to phospholipase A2 activity may play a role in regulating alkaline phosphatase activity in response to vitamin D metabolites and that this regulation in GC and RC may proceed by different mechanisms.
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PMID:The effects of vitamin D metabolites on phospholipase A2 activity of growth zone and resting zone cartilage cells in vitro. 325 18


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