Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) was found in extract of baker's yeast (Saccharomyces cerevisiae), and was purified to electrophoretic homogeneity using phosphocellulose adsorption chromatography and affinity elution by ATP. The enzyme shows cooperative binding of AMP (Hill coefficient, nH, 1.7) with an s0.5 value of 2.6 mM in the absence or presence of alkali metals. ATP acts as a positive effector, lowering nH to 1.0 and s0.5 to 0.02 mM. P1 inhibits the enzyme in an allosteric manner: s0.5 and nH values increase with increase in Pi concentration. In the physiological range of adenylate energy charge in yeast cells (0.5 to 0.9), the AMP deaminase activity increases sharply with decreasing energy charge, and the decrease in the size of adenylate pool causes a marked decrease in the rate of the deaminase reaction. AMP deaminase may act as a part of the system that protects against wide excursions of energy charge and adenylate pool size in yeast cells. These suggestions, based on the properties of the enzyme observed in vitro, are consistent with the results of experiments on baker's yeast in vivo reported by other workers.
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PMID:AMP deaminase from baker's yeast. Purification and some regulatory properties. 3 10

Purified rat muscle AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) binds tightly to rat myosin. The binding is abolished in the presence of low concentrations of various ligands. Pyrophosphate and GTP at concentrations as low as 0.1 micrometer were effective in abolishing the interaction between two proteins. Other nucleoside triphosphates were less effective than GTP and the concentrations required for 50% inhibition were approximately 0.3 to 0.7 micrometer. ADP and AMP are effective in inhibiting the interaction between two proteins, but they are less effective than the nucleoside triphosphates; 50% inhibition occurred at 34 micrometer with ADP and at 1 mM with AMP. Creatine phosphate and inorganic phosphate showed 50% inhibition at 5 to 6 mM. All of the compounds, which affected AMP deaminase activity, were effective in abolishing the interaction of the enzyme with myosin; however, the interaction-abolishing effects of the compounds are not parallel with their inhibitory effects on the deaminase activity. Although there exist three parental isozymes of AMP deaminase in the rat, all three enzymes interacted with myosin.
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PMID:Effects of various ligands on interaction of AMP deaminase with myosin. 20 24

The problems of whether the kinetic and regulatory properties of AMP deaminase were modified by formation of a deaminase-myosin complex were investigated with an enzyme preparation from rat skeletal muscle. Results showed that AMP deaminase was activated by binding to myosin. Myosin-bound AMP deaminase showed a sigmoidal activity curve with respect to AMP concentration in the absence of ATP and ADP, but a hyperbolic curve in their presence. Addition of ATP and ADP doubled the V value, but did not affect the Km value. Myosin-bound AMP deaminase also gave a sigmoidal curve in the presence of alkali metal ions, whereas free AMP deaminase gave a hyperbolic curve. GTP abolished the activating effects of both myosin and ATP.
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PMID:Interaction of rat muscle AMP deaminase with myosin. II. Modification of the kinetic and regulatory properties of rat muscle AMP deaminase by myosin. 42 Aug 60

Deamination of AMP in skeletal muscle sarcoplasmic reticulum followed by an increase in pH from 6,5 up to 8,0 leads in a liberation of part of Ca2+ from the SR vesicles. This effect is enhanced by K+, which activate the deamination, and is suppressed by Mg2+, which inhibit the reaction. The activating effect of AMP on Ca2+ efflux from the vesicles markedly decreases after AMP deaminase dissociation from the vesicles and is restored after reconstitution of their deaminase activity. Substitution of IMP for AMP causes a decrease of Ca2+ efflux from the vesicles. The data obtained are in good agreement with the assumption that the ammonium formation from AMP can favour the release of Ca2+ from some vesicles of SR.
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PMID:[Efflux of Ca2+ from fragmented sarcoplasmic reticulum during AMP deamination]. 50 58

The regulatory properties of adenylate deaminase (EC 3.5.4.6) from Ehrlich ascites tumor cells suggest that the reaction catalyzed by this enzyme serves to protect the cell against sharp decreases in the adenylate energy charge by removing adenosine 5'-monophosphate generated when the rate of utilization of adenosine triphosphate is suddenly increased. The enzyme is effectively inhibited under normal physiological conditions of high energy charge (0.9) and 4 to 5 mM adenine nucleotide pool size. The reaction is sharply activated by a decrease in the energy charge in the physiological range (0.9 to 0.6). At low energy charge (0.6), decrease in the size of the pool causes a marked and nonlinear decrease in the rate of the deaminase reaction. This effect presumably serves to prevent excessive depletion of the adenine nucleotide pool. Calculations based on the kinetic data obtained in this study show that the AMP deaminase reaction can account for the well-established alteration of adenine nucleotide metabolism that is observed following addition of glucose or 2-deoxyglucose to intact ascites cells.
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PMID:Role of the adenylate deaminase reaction in regulation of adenine nucleotide metabolism in Ehrlich ascites tumor cells. 94 36

Thick filaments in vertebrate striated muscles are composed of myosin heavy chain (MHC) and myosin light chains (MLCs) plus at least eight other proteins: C-protein, 86kD protein (birds) or H-protein (mammals), M-protein, myomesin, titin, MM-creatine kinase, skelemin, and AMP-deaminase. Except for CPK and AMP deaminase, none have well defined functions. Analysis of cDNA clones encoding chicken C-protein and 86kD protein has revealed a high degree of shared amino acid identity, particularly in the C-terminal 40kD. To identify functionally significant regions, the human counterpart of each protein was cloned, sequenced and analysed. Two human C-protein cDNAs were isolated with significant homology to chicken fast C-protein. Clone H75, with 69% identity to chicken fast C-protein, shows the same pattern of hybridization as the chicken fast C-protein in chicken muscles. The other clone, H8 with 60% identity, shows a pattern of hybridization in chicken muscles which is consistent with the expression of chicken slow C-protein. The human 86kD protein shares 66% DNA sequence identity with the chicken 86kD protein. Assuming that essential sequences would be conserved during evolution, we compared the chicken and human proteins using PALIGN. Chicken and human fast C-proteins possess 66% peptide identity over their deduced length plus 10% conservative substitutions. Human slow C-protein and chicken fast C-protein share 44% peptide sequence identity, plus 16% conservative substitutions. Chicken and human 86kD proteins are also very similar: 54% peptide identity plus 20% conservative substitutions. This high degree of sequence identity between chicken and human C- and 86kD proteins suggests selective pressure on the primary sequence. Recent primary sequence analyses of projectin and mini-titins from Drosophila, twitchin from C. elegans, C-protein, smMLCK, 86kD protein, and M-protein from the chicken, titin from the rabbit, and skelemin from the mouse reveals that all these proteins possess multiple internal repeats of approximately 100 amino acids. These repeating domains are of two types: one is homologous to the internal repeats which define the C-2 subset of the immunoglobulin superfamily, the other is related to the fibronectin type III repeat. Both human C-proteins possess comparable internal repeats and preliminary evidence suggests the presence of the same repeats in human 86kD. This duality of repeat structure is found in many extracellular proteins and is typified by the N-CAMs.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:cDNA cloning and sequence comparisons of human and chicken muscle C-protein and 86kD protein. 134 Oct 33

The enzymes involved in the purine interconversion pathway of wild-type and purine analog-resistant strains of Methanobacterium thermoautotrophicum Marburg were assayed by radiometric and spectrophotometric methods. Wild-type cells incorporated labeled adenine, guanine, and hypoxanthine, whereas mutant strains varied in their ability to incorporate these bases. Adenine, guanine, hypoxanthine, and xanthine were activated by phosphoribosyltransferase activities present in wild-type cell extracts. Some mutant strains simultaneously lost the ability to convert both guanine and hypoxanthine to the respective nucleotide, suggesting that the same enzyme activates both bases. Adenosine, guanosine, and inosine phosphorylase activities were detected for the conversion of base to nucleoside. Adenine deaminase activity was detected at low levels. Guanine deaminase activity was not detected. Nucleoside kinase activities for the conversion of adenosine, guanosine, and inosine to the respective nucleotides were detected by a new assay. The nucleotide-interconverting enzymes AMP deaminase, succinyl-AMP synthetase, succinyl-AMP lyase, IMP dehydrogenase, and GMP synthetase were present in extracts; GMP reductase was not detected. The results indicate that this autotrophic methanogen has a complex system for the utilization of exogenous purines.
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PMID:Genetic and physiological characterization of the purine salvage pathway in the archaebacterium Methanobacterium thermoautotrophicum Marburg. 234 48

Adenosine-5'-monophosphate deaminase is a critical enzyme in the regulation of adenine nucleotide levels in the erythrocyte. The routine examination of this enzyme in crude hemolysates is difficult with the commonly used assay which monitors ammonia generated by the deamination reaction. This report details a radioisotopic assay for AMP deaminase which allows separation of the [14C]inosine 5'-monophosphate product from the [14C]adenosine 5'-monophosphate substrate by ion-exchange chromatography at pH 2.2. The radioisotopic assay is linear with respect to time and enzyme concentration over a considerable range and thereby significantly simplifies the monitoring of crude or dilute enzyme preparations.
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PMID:Radioisotopic assay for erythrocyte adenosine 5'-monophosphate deaminase. 250 31

The pathways of AMP degradation and the metabolic fate of adenosine were studied in cultured myotubes under physiological conditions and during artificially induced enhanced degradation of ATP. The metabolic pathways were gauged by tracing the flow of radioactivity from ATP, prelabelled by incubation of the cultures with [14C]adenine, into the various purine derivatives. The fractional flow from AMP to inosine through adenosine was estimated by the use of the adenosine deaminase (EC 3.5.4.4) inhibitors, coformycin and 2'-deoxycoformycin. The activities of the enzymes involved with AMP and adenosine metabolism were determined in cell extracts. The results demonstrate that under physiological conditions, there is a small but significant flow of label from ATP to diffusible bases and nucleosides, most of which are effluxed to the incubation medium. This catabolic flow is mediated almost exclusively by the activity of AMP deaminase (EC 3.5.4.6), rather than by AMP 5'-nucleotidase (EC 3.1.3.5), reflecting the markedly higher Vmax/Km ratio for the deaminase. Enhancement of ATP degradation by inhibition of glycolysis or by combined inhibition of glycolysis and of electron transport resulted in a markedly greater flux of label from adenine nucleotides to nucleosides and bases, but did not alter significantly the ratio between AMP deamination and AMP dephosphorylation, which remained around 19:1. Combined inhibition of glycolysis and of electron transport resulted, in addition, in accumulation of label in IMP, reaching about 20% of total AMP degraded. In the intact myotubes at low adenosine concentration, the anabolic activity of adenosine kinase was at least 4.9-fold the catabolic activity of adenosine deaminase, in accord with the markedly higher Vmax/Km ratio of the kinase for adenosine. The results indicate the operation in the myotube cultures, under various rates of ATP degradation, of the AMP to IMP limb of the purine nucleotide cycle. On the other hand, the formation of purine bases and nucleosides, representing the majority of degraded ATP, indicates inefficient activity of the IMP to AMP limb of the cycle, as well as inefficient salvage of hypoxanthine under these conditions.
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PMID:Pathways of adenine nucleotide catabolism in primary rat muscle cultures. 282

The enzymes that catalyse the salvage of purines in Entamoeba histolytica trophozoites have been surveyed. Adenine deaminase (EC 3.5.4.2), adenosine deaminase (EC 3.5.4.4), guanine deaminase (EC 3.5.4.3), adenine phosphoribosyltransferase (PRTase) (EC 2.4.2.7), xanthine PRTase (EC 2.4.2.22) and hypoxanthine PRTase (EC 2.4.2.8) were all detected in cell homogenates but only at low activities, whereas AMP deaminase (EC 3.5.4.6) and guanine PRTase (EC 2.4.2.8) were not found. Phosphorylases (EC 2.4.2.1) active in both anabolic and catabolic directions were present and all nucleosides tested were phosphorylated by kinases (EC 2.7.1.15, EC 2.7.1.20, EC 2.7.1.73). 3'-Nucleotidase (EC 3.1.3.6) and 5'-nucleotidase (EC 3.1.3.5) were found, the former being mainly particulate. Nucleotide interconversion enzymes (adenylosuccinate lyase, EC 4.3.2.2; adenylosuccinate synthetase, EC 6.3.4.4; IMP dehydrogenase, EC 1.2.1.14; GMP synthetase, EC 6.3.5.2 and GMP reductase, EC 1.6.6.8) were not detected. The results suggest that in E. histolytica the main route of nucleotide synthesis is from the individual bases through the actions of phosphorylases and kinases.
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PMID:Purine-metabolising enzymes in Entamoeba histolytica. 287 91


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