Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

p-Nitrophenylphosphocholine phosphodiesterase activity was purified 5000-fold from mouse brain by treatment of membranes with Bacillus cereus phospholipase C preparation and sequential chromatographies on concanavalin A-Sepharose and CM-Sephadex columns. The phosphodiesterase (Zn(2+)-requiring) showed Km and Vmax. values of 5.5 microM and 4.2 mumol/min per mg respectively in the hydrolysis of p-nitrophenylphosphocholine, and possessed an optimum pH of 10.5 and a molecular mass of approx. 74 kDa. The purified enzyme was found to convert glycerophosphocholine into glycerol and phosphocholine, with Km and Vmax. of 48 microM and 5 mumol/min per mg respectively. In the hydrolysis of glycerophosphocholine the enzyme also exhibited a Zn2+ requirement and optimal pH at 10.5. Additionally, the p-nitrophenylphosphocholine phosphodiesterase activity was competitively inhibited by glycerophosphocholine, with a Ki value of 50 microM. These observations, together with chromatographic behaviour and heat-denaturation analyses, indicate that both p-nitrophenylphosphocholine phosphodiesterase and glycerophosphocholine cholinephosphodiesterase activities reside in the same protein.
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PMID:Characterization of a Zn(2+)-requiring glycerophosphocholine cholinephosphodiesterase possessing p-nitrophenylphosphocholine phosphodiesterase activity. 132 42

Glycerylphosphorylcholine (GPC) phosphocholine phosphodiesterase activity (EC 3.1.4.38) is significantly reduced in multiple sclerosis plaques compared to adjacent tissue with a P less than 0.01 based upon the Student-Newman-Keuls or Tukey test. This finding is in accord with the proposal that this particular form of the enzyme is myelin-specific. Similar activities for GPC phosphocholine phosphodiesterase were obtained with samples from various regions of the same individual brain.
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PMID:Glycerylphosphocholine phosphocholine phosphodiesterase activity is reduced in multiple sclerosis plaques. 216 15

Experiments with glycerophosphocholine phosphodiesterase (GPC diesterase, EC 3.1.4.2.) in rat brain microsomes suggest that, although its activity is inhibited by low concentrations of calmidazolium, its dependence on Ca2+ ions is not modulated by calmodulin. The activity of glycerophosphocholine choline phosphodiesterase (choline phosphohydrolase, EC 3.1.4.38) was much lower than that of the GPC diesterase. A relatively inexpensive method for the preparation of sn-glycero-3-phospho [Me-14C]choline is described.
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PMID:The hydrolysis of glycerophosphocholine by rat brain microsomes: activation and inhibition. 303 33

Inhibition of a Zn(2+)-glycerophosphocholine cholinephosphodiesterase by thiols or tellurites were examined mechanistically. Inactivation of the phosphodiesterase by thio-carboxylates, which was due to the removal of Zn2+ in the catalytic site, was enhanced by introduction of an amino group in the structure of thiols, suggesting the presence of an anionic site adjacent to a Zn2+ site. In support of the suggestion, it was found that thiols, associable with both a Zn2+ site and an anionic site, were more potent reversible inhibitors; dimethylaminoethanethiol (Ki, 17 microM), diethylaminoethanethiol (Ki, 1.2 microM) and thiocholine (Ki, 2.6 microM). Meanwhile, the inhibition of the phosphodiesterase by tellurites is ascribed to the binding of tellurite anions to a Zn2+ site, based on the protective action of tellurite anions against the inactivation of the enzyme by EDTA. Moreover, the inhibition of the phosphodiesterase by tellurites was prevented by phosphate ions, which expressed the protective effect against EDTA inactivation. In further support, it was observed that tellurite and thiocholine appeared to interact with active site in an additive manner, in contrast to a synergistic action between tellurites and quaternary ammonium compounds such as acetylcholine or choline.
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PMID:Involvement of both a Zn2+ site and an anionic binding site in the selective inhibition of a Zn(2+)-glycerophosphocholine cholinephosphodiesterase by thiols and tellurites. 778 39

A Zn(2+)-glycerophosphocholine cholinephosphodiesterase was purified with a specific activity of 4.6 mumole/min.mg protein from bovine brain membranes by procedures involving PI-PLC solubilization, concanavalin A affinity chromatography, CM-sephadex chromatography and Sephadex G-150 chromatography. Based on molecular weight determination gel chromatography and SDS polyacrylamide gel electrophoresis, the phosphodiesterase activity appears to be a dimeric protein (110 kDa) composed of two subunits with a molecular weight of approximately 54 kDa. The K(m) value for p-nitrophenylphosphocholine and the optimum pH were found to be 16 microM and pH 10.5, respectively. The phosphodiesterase was inhibited by Cu2+, but not the other divalent metal ions. The activity of the apoenzyme was remarkably activated by Co2+ or Zn2+, but not Mn2+ or Mg2+. In addition, the inactivation of the enzyme in glycine buffer was prevented by Mn2+ or Zn2+, but not Co2+ or Mg2. In a separate experiment, comparing properties of the purified and membrane-bound phosphodiesterases, the forms of two enzymes were quite similar except in stability. Both enzymes were more stable at pH 7.4 than pH 5 or 10. However, the membrane-bound enzyme was more stable than the soluble enzyme at all three pHs. These data suggest that the activity of the phosphodiesterase may be stabilized in-vivo.
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PMID:Properties of a Zn(2+)-glycerophosphocholine cholinephosphodiesterase from bovine brain membranes. 892 80

The effect of divalent metal ions on the activity of glycerophosphocholine cholinephosphodiesterse from ox brain was examined. Zn(2+)- and Co(2+)-glycerophosphocholine cholinephosphodiesterases were prepared from the exposure of apoenzyme to Zn2+ and Co2+, respectively, and the properties of two metallo-phosphodiesterases were compared to those of native phosphodiesterase. Although two metallo-enzymes were similar in expressing Km value, optimum pH or sensitivity to Cu2+, they differed in the susceptibility to the inhibition by thiocholine or tellurite; while Co(2+)-phosphodiesterase was more sensitive to tellurites, Zn(2+)-phosphodiesterase was more susceptible to inhibition by thiocholine. In addition, Zn(2+)-phosphodiesterase was more thermo-stable than Co2+ enzyme. Separately, when properties of native phosphodiesterase were compared to those of each metallo-phosphodiesterase, native phosphodiesterase was found to be quite similar to Zn(2+)-phosphodiesterase in many respects. Even in thermo-stability, native enzyme resembled Zn(2+)-phosphodiesterase rather than Co(2+)-enzyme. Consistent with this, the stability of native phosphodiesterase was maintained in the presence of Zn2+, but not Co2+, Mn2+ was also as effective as Zn2+ in the stabilization of the enzyme. Noteworthy, the native enzyme was found to be inhibited competitively by Cu2+ with a Ki value of 20 microM, and its inhibitory action was antagonized effectively by Zn2+ or Co2+. Also, choline, another competitive inhibitor of the enzyme, appeared to antagonize the inhibitory action of Cu2+. Taken together, it is suggested that there may be multiple binding sites for divalent metal ions in the molecule of glycerophosphocholine cholinephosphodiesterase.
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PMID:Interaction of divalent metal ions with Zn(2+)-glycerophosphocholine cholinephosphodiesterase from ox brain. 935 12

Zn2+-glycerophosphocholine cholinephosphodiesterase, responsible for the conversion of glycerophosphocholine into glycerol and phosphocholine, was inactivated during incubation with ascorbic acid at 38 degrees C. The inclusion of copper ions or Fe2+ accelerated the ascorbate-induced inactivation, with Cu2+ or Cu+ being much more effective than Fe2+, suggestive of ascorbate-mediated oxidation. Dehydroascorbic acid had no effect on the phosphodiesterase, but H2O2 inactivated the enzyme in a concentration-dependent manner. Also, the enzyme was inactivated partially by a superoxide anion-generating system but not an HOCl generator. In support of involvement of H2O2 in the ascorbate action, catalase and superoxide dismutase expressed a complete and a partial protection, respectively. However, hydroxy radical scavengers such as mannitol, benzoate, or dimethyl sulfoxide were incapable of preventing the ascorbate action, excluding the participation of extraneous .OH. Although p-nitrophenylphosphocholine exhibited a modest protection against the ascorbate action, a remarkable protection was expressed by amino acids, especially by histidine. In addition, imidazole, an electron donor, showed a partial protection. Separately, when Cu2+-induced inactivation of the phosphodiesterase was compared with the ascorbate-mediated one, the protection and pH studies indicate that the mechanism for the ascorbate action is different from that for the Cu2+ action. Here, it is proposed that Zn2+-glycerophosphocholine cholinephosphodiesterase is one of brain membrane proteins susceptible to oxidative inactivation.
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PMID:Ascorbate-induced oxidative inactivation of Zn2+-glycerophosphocholine cholinephosphodiesterase. 948 38

Properties of active site of Zn2+-glycerophosphocholine cholinephosphodiesterase from ox brain were examined using substrates and inhibitors of the phosphodiesterase. The anionic binding site expressed a selectivity for a positively-charged group. Meanwhile, the glyceryl moiety-binding site appeared to be a narrow crevice of a limited size, excluding the entry of acylglycerophospholipids containing long acyl chains. While endogenous quaternary ammonium compounds such as phosphocholine, choline or carnitine inhibited the enzyme, divalent metal ions such as Co2+, Mn2+ or Zn2+ enhanced the activity by 1.5 to 2-folds. The pH dependence for the inhibition by phosphocholine or the hydrolysis of substrate implies the involvement of a basic amino acid residue with a pK value of 9.6-9.7, probably lysine, in the binding of phosphoryl group. In further support, the lysine modifiers such as trinitrobenzene sulfonic acid or diethylpyrocarbonate expressed some inactivation. The pH-rate profile indicates that an amino acid residue with a pK value of 10.2, presumably tyrosine, may participate as a nucleophile in the catalysis. This might be further supported by the inactivation of the enzyme by tyrosine modifiers such as tetranitromethane or HOI-generating system. Separately, the phosphodiesterase was observed to be susceptible to the action of hydrogen peroxide or peroxynitrite-generating system. From these results, it is implied that the phosphodiesterase may be affected by endogenous sources.
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PMID:Active site of brain Zn2+-glycerophosphocholine cholinephosphodiesterase and regulation of enzyme activity. 970 95