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)

1-Pyrrolidinecarbothioic acid (2-pyridylmethylene) hydrazide chelates Zn2+ but not Mg2+. This compound is about twice as effective as EDTA for inhibiting alkaline phosphatase from calf mucosa, and approx. 1000-fold more effective than EDTA for inhibiting acid phosphatase from wheat germ. The compound did not inhibit pyridoxine kinase activity in human leucocytes at the highest concentration tested (33 micron). Therefore it may be a useful tool for either examining or eliminating the effects of phosphatases in complex enzyme systems.
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PMID:Simplified preparation of a phosphatase inhibitor and further studies of its action. 65 57

Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythrocyte PLP levels increase threefold over nonpregnant levels. These studies were designed to determine whether changes in the enzymes involved in synthesis and degradation of PLP in blood are altered during pregnancy. We measured net synthesis of PLP in erythrocytes and the activity of enzymes involved in the regulation of plasma and erythrocyte PLP concentration: erythrocyte pyridoxal kinase (PLK) and neutral phosphatase, and plasma and tissue alkaline phosphatase (ALP). Net synthesis of PLP and activities of erythrocyte PLK and neutral phosphatase in erythrocytes remained unchanged during pregnancy. We were unable to detect any dephosphorylation of PLP in erythrocytes of pregnant or nonpregnant mice. Mouse erythrocytes were devoid of ALP activity; neutral phosphatase was inactive with PLP and PLP was an uncompetitive inhibitor of the enzyme. Plasma ALP activity decreased 50% in the pregnant mice; therefore, it likely does not participate in the reduction of plasma PLP levels during pregnancy. Placenta had high levels of PLP-phosphatase activity (ALP) and, if it is active as an ectoenzyme in this tissue as it is in others, it may be the most important mediator of plasma PLP levels in pregnancy.
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PMID:Vitamin B-6 metabolic enzymes in blood and placenta of pregnant mice. 215 29

Physical interactions between pyridoxal kinase and aspartate aminotransferase were detected by means of emission anisotropy and affinity chromatography techniques. Binding of aspartate aminotransferase (apoenzymes) to pyridoxal kinase tagged with a fluorescent probe was detected by emission anisotropy measurements at pH 6.8 (150 mM KCl). Upon saturation of the kinase with the aminotransferase, the emission anisotropy increases 22%. The protein complex is characterized by a dissociation constant of 3 microM. Time-dependent emission anisotropy measurements conducted with the mixture 5-naphthylamine-1-sulfonic acid-kinase aspartate aminotransferase (apoenzyme), revealed the presence of two rotational correlation times of phi 1 = 36 and phi 2 = 62 ns. The longer correlation time is attributed to the stable protein complex. By immobilizing one enzyme (pyridoxal kinase) through interactions with pyridoxal-Sepharose, it was possible to demonstrate that aspartate aminotransferase releases pyridoxal kinase. A test of compartmentation of pyridoxal-5-phosphate within the protein complex using alkaline phosphatase as trapping agent, indicates that the cofactor generated by the catalytic action of the kinase is channeled to the apotransaminase. The main function of the stable complex formed by the kinase and the aminotransferase is to hinder the release of free pyridoxal-5-phosphate into the bulk solvent.
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PMID:Interactions of pyridoxal kinase and aspartate aminotransferase emission anisotropy and compartmentation studies. 284 32

The etiology of vitamin B(6) depletion in inflammation remains unknown. Hepatic vitamin B(6) decreased in adrenalectomized rats, and such reductions were restored by an acute muscle injection of a very high dose of glucocorticoids. We tested the hypothesis that long-term prednisolone treatment for treating inflammation restores vitamin B(6) status by induction of tissue B6 metabolic enzymes. Two independent in vivo models were used. Lewis rats and C57BL/6J mice received prednisolone regimens that reflected clinical prednisolone uses in treating human inflammation. We found: 1) prednisolone increased circulating B6 vitamer pyridoxal 5'-phosphate (PLP; bioactive B6 vitamer), pyridoxal (PL), and 4-pyridoxic acid without altering vitamin B(6) excretion; 2) prednisolone simultaneously induced the hepatic PLP-synthesizing enzyme pyridoxine kinase (PDXK) and pyridoxamine-5'-phosphate oxidase (PMPO) and suppressed PLP catabolic enzyme pyridoxal-5'-phosphate phosphatase (PDXP); and 3) elevations in circulating PL were caused by its release from the liver, not by PLP dephosphorylation (PDXP was suppressed and alkaline phosphatase was unaltered). We conclude that long-term prednisolone treatments promoted hepatic bioactive vitamin B(6) synthesis by inducing the synthesizing enzymes PDXK and PMPO and simultaneously suppressing the catabolic enzyme PDXP. Prednisolone increased circulating B6 vitamer without altering urinary B6 excretion. As the major form of vitamin B(6) across cell membrane, elevated circulating PL may facilitate the cellular uptake and utilization of B6. The elevated plasma PLP may increase vitamin B(6) supply to tissues with a higher B6 demand during inflammation. Results from two independent in vivo models suggested a potential advantage of clinical prednisolone use in treating inflammation with respect to vitamin B(6) status.
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PMID:Long-term prednisolone treatments increase bioactive vitamin B6 synthesis in vivo. 2120 17