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

khe conformational and functional events in calmodulin (CaM) are disproportionate to the mean saturation by Ca2+. The enhancement of intrinsic tyrosine fluorescence closely follows the appearance of species CaM X Can greater than or equal to 1; the exposure of the hydrophobic patch at the surface of CaM coincides with the appearance of CaM X Can greater than or equal to 2. For the activation of four different target enzymes, i.e., brain phosphodiesterase and adenylate cyclase, red blood cell Ca,Mg-ATPase, and skeletal muscle phosphorylase b kinase, CaM X Can greater than or equal to 3 is required. The different enzymes have the same affinity for the active species. The direct interaction of CaM with Ca2+ and phosphorylase b kinase has been analyzed according to the theory of energy coupling: whereas the first two stoichiometric calcium-binding constants in the complex are not significantly different from those of free CaM, the third Ca2+ binds with an affinity at least 10(6)-fold higher to enzyme-bound CaM than to free CaM, which corresponds to a free energy coupling of -7 kcal/mol CaM. The similarities in the activation mechanism of different enzymes suggest the existence of one unique CaM-binding domain. The characteristics of the interaction between CaM and melittin, a small amphiphatic cytotoxin, led us to propose melittin as a model for such a CaM-binding domain.
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PMID:Sequential events in calmodulin on binding with calcium and interaction with target enzymes. 650 74

The activation of phosphorylase kinase during limited proteolysis by subtilisin was studied. It was shown that phosphorylase kinase undergoes rapid activation and its activity remains unchanged throughout a prolonged incubation. Electrophoresis in the presence of Na-SDS revealed a rapid decomposition of the alpha-subunit and a gradual disappearance of the beta-subunit; the protein molecule was shown to be composed of the degradation products of alpha- and beta-subunits with different molecular weights and unchanged proteolysis of the gamma-subunit. The phosphorylase kinase hydrolysate was separated using chromatography on a cellulose phosphate column. The active protein fraction contains a new form of phosphorylase kinase with a low molecular weight (approximately 80 000) which is insensitive to Ca2+. The subtilisin-activated phosphorylase kinase does not affect the activity of phosphodiesterase from cyclic nucleotides.
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PMID:[Properties of phosphorylase kinase activated by subtilisin]. 701 93

The focus of this study was to identify the molecular basis for the hypersensitive response of glycogen phosphorylase activation to epinephrine stimulation in alloxan diabetic-derived cardiomyocytes. Cyclic AMP levels were found not to be significantly different between normal and diabetic-derived cells while cGMP concentrations were found consistently to be significantly lower in diabetic-derived cells than in normal cells. Treatment with cyclic GMP analogues did not affect phosphorylase activation by epinephrine in normal cardiomyocytes whereas, IBMX, a nonselective phosphodiesterase inhibitor, had a significant effect on basal and agonist-stimulated phosphorylase activity in both normal and diabetic-derived cardiomyocytes. Differences in the time course for the rate of decay of phosphorylase a from agonist-stimulated to basal levels were observed between normal and diabetic cells. After 3 h in primary culture, phosphorylase a activity returned to basal levels more quickly in normal than in diabetic-derived cells while after 24 h in culture, the time for phosphorylase a decay was not significantly different between normal and diabetic myocytes and was longer than the 3 h response. After 3 h response. After 3 h in primary culture, no significant difference in phosphorylase kinase activity was observed between normal and diabetic-derived cells exposed to epinephrine whereas, after 24 h in culture, phosphorylase kinase activity was significantly decreased in diabetic cells under basal and agonist-stimulation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of the molecular basis for phosphorylase hypersensitivity in cultured diabetic cardiomyocytes. 767 33

Mycelia of Phymatotrichum omnivorum obtained at 10 day intervals during 10 to 50 days of growth were used for isolating calmodulin, and studying its effect on glycogen synthase, phosphorylase, phosphorylase kinase, cyclic AMP phosphodiesterase and Ca++ATPase. Glycogen synthase was inhibited until the 30th day by calmodulin, whereas calmodulin obtained from the 40th day stimulated glycogen synthase activity and the 50th day sample had no effect. cAMP phosphodiesterase and Ca++ATPase of P. omnivorum were stimulated by the respective calmodulin. Molecular weight of the purified fungal calmodulin was approximately 18 kD as revealed by sodium dodecyl sulphate gel electrophoresis. Trifluoperazine, dibucaine and lidocaine inhibited calmodulin activity and calmodulin activation of PDE, respectively.
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PMID:Purification and properties of calmodulin from Phymatotrichum omnivorum. 838 68


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