Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Several compounds were tested as inhibitors of the alkaline phosphatase (AlkPase) activity associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta. Molybdate, arsenate, arsenite and beta-glycerophosphate (BGP) were competitive inhibitors of the hydrolysis of p-nitrophenyl phosphate, while levamisole and clorsulon were uncompetitive and mixed inhibitors, respectively. Molybdate was also a competitive inhibitor of the hydrolysis of BGP and 5'-adenosine monophosphate, and levamisole was an uncompetitive inhibitor of BGP hydrolysis. The apparent inhibitor constants (Ki') for molybdate and levamisole were virtually identical regardless of the substrate, and these data support the hypothesis that the AlkPase activity is represented by a single membrane-bound enzyme with low substrate specificity. Quinacrine, Hg2+, and ethylenediaminetetraacetate were also potent inhibitors of the AlkPase activity, but the mechanisms by which these latter three inhibitors function were not clear.
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PMID:Competitive, uncompetitive, and mixed inhibitors of the alkaline phosphatase activity associated with the isolated brush border membrane of the tapeworm Hymenolepis diminuta. 276 48

We have studied the cytosolic estrogen receptor in uterus of rats after castration and diabetes induction with Streptozotocin, and the relationship of estradiol (E2) binding with phosphatase activities. Ovariectomy (OVX) and diabetes produced a significant reduction in Type I and II binding sites, but did not affect the equilibrium dissociation constants. The reduction of receptor levels was partially reversed by homogenization and incubation with 20 mM molybdate (MoO4) and also by chronic treatment with E2. Considering the possibility that the increase in E2 binding in the presence of MoO=4 was due to phosphatase inhibition, the activities of these enzymes hypothetically involved in receptor dephosphorylation and inactivation were determined in uterine homogenate and cytosol from intact, OVX, and diabetic rats with and without E2 treatment. Chronic OVX and diabetes induced stimulation of alkaline, acid and neutral phosphatase activities. On the contrary, the increment of estrogenic receptors due to E2 treatment was not correlated with changes in phosphatase activity. It is possible that this effect was due to the protection of the receptor or to the induction of receptor synthesis by E2. Molybdate inhibited acid and neutral phosphatases and increased alkaline phosphatase, which suggest that neutral and acid phosphatases are identical and that they were responsible for the receptor inactivation. However, it is unclear at present the relationship between the increment of alkaline phosphatase and the reduction of receptors.
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PMID:Estradiol binding and phosphatase activity in the uterus after castration and chronic diabetes: effect of molybdate and estrogen replacement. 300 2

We have recently purified the modulator of the glucocorticoid-receptor complex from rat liver. Purified modulator inhibits glucocorticoid-receptor complex activation and stabilizes the steroid-binding ability of the unoccupied glucocorticoid receptor. Since these activities are shared by exogenous sodium molybdate, modulator appears to be the endogenous factor that sodium molybdate mimics. In this report, we present additional evidence for the mechanism of action of purified modulator. (i) Molybdate and modulator inhibit receptor activation as measured by DNA-cellulose binding, DEAE-cellulose chromatography, and Sepharose 4B gel filtration. (ii) The ability of molybdate and modulator to inhibit receptor activation and stabilize the unoccupied receptor appears to be additive. (iii) Scatchard analysis of heat-destabilized unoccupied receptors indicates that the number of steroid-binding sites is reduced during destabilization, whereas the steroid dissociation constant remains unchanged. Molybdate and modulator stabilize the receptor by maintaining the number of steroid-binding sites. (iv) Molybdate and modulator do not inhibit alkaline phosphatase-induced destabilization of the unoccupied receptor. However, alkaline phosphatase-induced destabilization is reversed by the addition of dithiothreitol in the presence, but not in the absence, of molybdate or modulator. These results suggest that the mechanism of action for modulator is identical to that of sodium molybdate, and we propose that modulator is the endogenous molybdate factor for the glucocorticoid receptor.
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PMID:Evidence that the modulator of the glucocorticoid-receptor complex is the endogenous molybdate factor. 342 44

Glucocorticoid receptor in rat liver cytosol is inactivated (rendered unable to bind steroid) by incubation with calf intestine alkaline phosphatase or highly purified rabbit muscle phosphoprotein phosphatase (phosphorylase phosphate, protein phosphatase C). The receptor is inactivated by both enzymes even when 10 mM sodium molybdate is present. Receptors that are inactivated by phosphatases in the presence of molybdate can be reactivated to the steroid-binding state by addition of dithiothreitol, but receptors that are inactivated in the absence of molybdate cannot be reactivated. These observations suggest that dephosphorylation leads to oxidation of a moiety (-SH) on the receptor that is required for steroid binding. Molybdate apparently preserves the receptor in a form such that reduction returns the receptor to the steroid binding state. We would propose that molybdate may act by complexing with sulfur groups on the receptor.
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PMID:Inactivation of glucocorticoid-binding capacity by protein phosphatases in the presence of molybdate and complete reactivation of dithiothreitol. 628 38

A series of compounds was tested for the inhibition of binding of the estradiol-receptor complex from chick oviduct to DNA. Most of the inhibitory substances were also found to elute bound receptor complex from DNA. Only a few had inhibitory properties without an eluting capacity. One of these compounds is periodate which, to our knowledge, has not been studied up to now as an inhibitor of steroid hormone receptors. Therefore, we investigated the effects of periodate on the estrogen-receptor complex in more detail and compared them to those of the two known inhibitors, molybdate and o-phenanthroline. Periodate reacts irreversibly with the non-activated estrogen receptor from chick oviduct and blocks activation. It also affects the activated form of the receptor causing an irreversible loss of its DNA binding ability. This process is termed disactivation. Molybdate is able to inhibit the temperature, as well as the salt induced activation in a reversible manner. However, it cannot disactivate the active form of the receptor. In contrast, o-phenanthroline appears to be unable to influence the activation process i.e. to react with the non-activated form of the receptor, but instead disactivates the activated receptor. The simultaneous determination of alkaline phosphatase inhibition by some of the tested compounds did not allow to decide if a dephosphorylation step is required for the activation of the estrogen receptor.
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PMID:Disactivation and inhibition of activation of the estrogen receptor from chick oviduct by periodate - comparison with the effects of molybdate and o-phenanthroline. 631 36

The product of the dye gene of Escherichia coli, mapping at 99-100 min, is required for expression of the sex factor F, and also appears to be involved in the regulation of envelope proteins. Mutation of dye thus results in loss of expression of the F-factor ( Fex -), i.e. male sterility, and dye sensitivity (Dyes). We have isolated a plasmid, pRB38 , in which a 6 kb SalI fragment carrying the dye+ gene was cloned into the plasmid pACYC184. This 6 kb SalI fragment also carries two nearby markers, chlG , involved in the synthesis of the molybdenum cofactor, and phoM, required for constitutive expression of alkaline phosphatase. Some of the polypeptides synthesised by pRB38 were identified using the maxi-cell procedure. The product of the dye gene was found to be a polypeptide of Mr = 29,000. Thus derivatives of pRB38 in which the transposon gamma delta was inserted into dye, resulting in a Dyes Fex - phenotype when these plasmids were in a delta dye strain, failed to a produce this polypeptide and in some cases produced a truncated product. Such insertions also resulted in a Chlr and Pho- phenotype when the plasmid was in a delta (dye- chlG -phoM) phoR strain, although complementation tests suggested that the phoM+ and chlG + genes were still intact. Insertions of gamma delta into the promoter distal end of dye did not result in a Dyes Fex - phenotype, although a truncated Dye protein was synthesised, and a Chlr Pho- phenotype was produced. It has been suggested ( Gaffney et al. 1983) that the dye (= sfrA ) gene product is necessary for F-factor expression because it is required for translocation of the F-factor TraJ protein to the outer membrane.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of the dye gene product, mutational loss of which alters envelope protein composition and also affects sex factor F expression in Escherichia coli K-12. 632 16

A fluorescent oxidation product of the molybdenum cofactor was isolated from Escherichia coli nitrate reductase (EC 1.9.6.1) and bovine milk xanthine oxidase (EC 1.2.3.2), which showed a visible absorption band at 395 nm and was dephosphorylated by alkaline phosphatase but not by phosphodiesterase I. The dephosphorylated species was oxidized by periodate to thieno[3,2-g]pterin-2-carbaldehyde which was quantitatively converted to thieno[3,2-g]pterin-2-carboxylic acid by subsequent treatment with Ag2O in 2 N NaOH. These results indicate that the oxidation product of the molybdenum cofactor is a thieno[3,2-g]pterin derivative with an unidentified side chain in the 2 position.
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PMID:Formation of thieno[3,2-g]pterines from the molybdenum cofactor. 634 Jun 73

A modified enzyme-linked immunosorbent assay (ELISA), with alkaline phosphatase as enzyme, was used for the study of antigenicity of lipid A fractions directly on thin-layer chromatographic (TLC) plates. For visualization a gel slab containing the enzyme substrate was placed on the plate containing enzyme-conjugated antibodies. The plate was read by a thin-layer chromatogram spectrophotometer. The immunoassay was both highly specific and quite sensitive. Sensitivity was superior to levels obtained by staining the plate with molybdenum blue (for phosphate) or orcinol (for carbohydrate). Fractions of lipid A from Escherichia coli 0111, Shigella flexneri or Salmonella minnesota R595, after being separated by thin-layer chromatography, were analyzed using rabbit anti-(lipid A) serum. Patterns obtained by scanning the same plates for phosphate staining and for the TLC-ELISA corresponded well. For comparison with TLC-ELISA, an inhibition assay was run using a tube ELISA. The tube ELISA, run in aqueous medium, showed that fractions 6-8 (those having the highest RF values) had the least activities. In contrast, TLC-ELISA did not detect large differences between fractions 2-7. This discrepancy probably reflected limited aqueous solubility of fractions 6 and 7. We conclude that TLC-ELISA might reveal antigenic activities of lipids that could be missed by other methods. The data suggested that all fractions, except for fraction 8, were similar in their antigenicity by TLC-ELISA. Differences in antigenicity between the fractions occurred when the fractions were tested in free form in an aqueous environment and these differences possibly could have been due to different solubilities of individual fractions.
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PMID:Lipid A fractions analyzed by a technique involving thin-layer chromatography and enzyme-linked immunosorbent assay. 636 43

Glucocorticoid receptors in cytosol preparations from rat liver or mouse L cells are inactivated by phospholipase A2 or calf intestine alkaline phosphatase. Molybdate ion, an inhibitor of a variety of phosphatase enzymes, does not prevent inactivation of glucocorticoid binding capacity by alkaline phosphatase but it blocks inactivation by phospholipase A2. In neither case is the enzyme itself inhibited, and the effect of molybdate on phospholipase-mediated inactivation appears to reflect the ability of molybdate to prevent receptor inactivation by the detergent action of lysophosphatides.
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PMID:Glucocorticoid receptor stabilization: relative effects of molybdate ion on inactivation by alkaline phosphatase and phospholipase A2. 686 2

The molybdenum cofactor common to a variety of molybdoenzymes has been shown to contain a novel pterin. The pterin has been isolated from sulfite oxidase from several sources, xanthine-oxidizing enzymes from milk and chicken liver, and nitrate reductase of Chlorella vulgaris after denaturation of the proteins in the presence of I2. Investigation of the anionic nature of the isolated pterin has revealed that it is a monophosphate ester susceptible to cleavage by alkaline phosphatase. Quantitative analyses have shown that one molecule of the pterin phosphate is associated with each molybdenum atom in sulfite oxidase. Studies to date have shown that the pterin is present in a reduced form in sulfite oxidase and xanthine dehydrogenase, and that in situ oxidation of the pterin leads to inactivation of sulfite oxidase.
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PMID:The pterin of the molybdenum cofactor. 695 16


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