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:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Muscle actin is, in most cases, prepared from an acetone-dried powder of the myosin-removed myofibrils under low-salt conditions in the presence of ATP. In this paper, it is shown that G-actin can be directly extracted from the myosin-removed myofibrils without acetone treatment. The extraction conditions are the same as those used for the extraction of G-actin from the dried powder: extraction of the myosin-removed myofibrils for 1 h with 2 mM Tris-HCl, pH 8.0, in the presence of 0.5 mM ATP. However, the crude G-actin directly extracted from the myosin-removed myofibrils loses its polymerizability after prolonged extraction. Measurements of inorganic phosphate and thin layer chromatography of the adenine nucleotides of the crude G-actin solution show that free ATP added to the extraction buffer is sequentially hydrolyzed to ADP and AMP, and then finally converted to IMP. The instability of the G-(ADP)-actin, depolymerized from the ends of actin filaments, explains the loss in polymerizability of G-actin during the extraction. Residual ATPase, adenylate kinase, and deaminase contained in the myofibrils may account for the decomposition of ATP.
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PMID:Direct extraction of G-actin from the myosin-removed myofibrils under the conditions of low ionic strength. 716 Dec 61

When added to medium containing coformycin (2 microM or above), adenine is lethal to Chinese hamster fibroblasts at the concentration inhibiting de novo purine biosynthesis (Debatisse and Buttin, '77b). Rescue by hypoxanthine suggested that cells die of IMP starvation when the analog can turn off deamination of both adenosine and adenylate. As predicted from this hypothesis, two classes of variants resistant to the mixture of coformycin + adenine have been isolated: Class 1 variants have altered control of de novo IMP biosynthesis; they fall into two subclasses on the basis of their resistance to adenosine. Class 2 variants have a 6-10-fold increased level of AMP-deaminase (E.C.: 3.5.4.6); their growth in the selective medium is temperature-dependent, a property accounted for by the observation that cell growth in the presence of coformycin imposes a gradual thermodependent decay of specific AMP-deaminase activity in both wild-type and variant lines. This control by coformycin of AMP-deaminase activity is unaltered in mutants deficient in the four activities of adenosine-kinase. APRT, HGPRT and deoxycytidine-kinase. Most of the resistant variants are unstable and exhibit either increased or reduced resistance, depending on prolonged growth in selective or normal medium.
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PMID:The potentiation of adenine toxicity to Chinese hamster cells by coformycin: suppression in mutants with altered regulation of purine biosynthesis or increased adenylate-deaminase activity. 720 4

Isolation and partial purification of AMP-deaminase from subfraction of soluble proteins of the mitochondrial fraction from rat liver is described. The enzyme preparations obtained deaminated AMP at the highest rate from pH 6.4 to 6.6. At the optimal pH value and in presence of optimal AMP concentrations the AMP-deaminase preparation was not activated by ATP or K+ and was inhibited by inorganic phosphate. Relationship was noted between both the content of protein in the enzyme preparations and length of the interval from composing the samples to monitoring the enzymatic activity and the following parameters of the AMP-deaminase: (a) shape of curves describing the rate of AMP deamination as a function of the nucleotide concentration, (b) reversible decrease in the AMP-deaminating activity after dialysis, (c) properties to deaminate, besides AMP, also some other nucleotides (ADP, NAD, FAD), (d) dynamics of inactivation of the enzyme preparations by controlled heating. The properties of the partially purified AMP-deaminase from the subfraction of rat liver soluble mitochondrial proteins were not identical with those described previously for other AMP-deaminases.
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PMID:[Partial purification and properties of the adenylate deaminase from subfractions of soluble mitochondrial proteins of rat liver]. 728 62

1 Dilazep, a coronary dilator, has been reported to potentiate the negative inotropic and negative chronotropic responses of guinea-pig atria to adenosine. Studies were made on the mechanism of the potentiating action of dilazep with special reference to the degradation and uptake of adenosine. 2 The negative inotropic actions of adenosine and adenine nucleotides, such as ATP, ADP, AMP and cyclic AMP, on guinea-pig atria were selectively and dose-dependently augmented by dilazep at concentrations insufficient to produce any effect alone (0.01 to 1 microM). 3 Incubation of atrial tissue with 8.8 nM adenosine, containing 0.1 microCi of [3H]-adenosine, resulted in accumulation of [3H]-adenosine in the tissue; dilazep (0.01 to 1 microM) inhibited this accumulation. 4 Adenosine (10 microM to 10 mM) was degraded to inosine and hypoxanthine during incubation with atrial tissue; dilazep (0.1 to 10 microM) retarded the disappearance of adenosine and the formation of inosine and hypoxanthine. 5 These results suggest that dilazep potentiates the negative inotropic effect of adenosine on guinea-pig atria by preventing both its accumulation by atrial tissue and degradation by deaminase.
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PMID:Potentiation by dilazep on the negative inotropic effect of adenosine on guinea-pig atria. 735 12

AMP-deaminase was purified from trout white muscle and some of its properties were investigated. The enzyme preparation was electrophoretically homogeneous; the molecular mass of the polypeptides was equal to 71600 +/- 550 Da, the specific activity was 200-500 U./mg of protein. Activation of the enzyme caused by acidification of the medium in the physiological range of pH was the result of reduction of Km for the substrate. ADP and ATP activated the enzyme, while GTP inhibited it. The enzyme was also inhibited by IMP (this phenomenon had never been described before). A change in pH within the physiological range of pH (6.6-7.3) had no influence on ATP, GTP or IMP effects on AMP-deaminase. The enzyme activation by ADP was sensitive to pH. The possibilities of fish muscle AMP-deaminase regulation under conditions of intensified metabolism is discussed.
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PMID:[Purification and characteristics of AMP-deaminase from trout white muscle]. 771 68

The three major isoforms of AMP-deaminase (AMPda) were localized in human skeletal muscle and cultured muscle cells by immunocytochemistry. The M isoform was mainly located in Type II muscle fibers and showed a clear cross-striation. Particularly strong staining was present at the neuromuscular junction. Capillaries were also immunoreactive. The L isoform was predominantly observed in nerve bundles and to a minor extent in smooth muscle cells and endothelial cells. The E isoform was predominantly present in smooth muscle cells, and to a lesser extent in Type I muscle fibers and nerve bundles. In quadriceps muscle of patients with myoadenylate deaminase deficiency, no immunostaining for the M isozyme was observed, whereas reactivity for the L and E isoforms was unaltered. In human muscle cell cultures, mononuclear cells, including myoblasts, were immunoreactive for the L isoform and to a lesser extent the E isoform, whereas the M isoform was absent. In myotubes, diffuse or fibrillar staining was present for all three isoforms, but only the M isoform showed a clear cross-striation pattern in highly differentiated myotubes.
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PMID:Immunolocalization of AMP-deaminase isozymes in human skeletal muscle and cultured muscle cells: concentration of isoform M at the neuromuscular junction. 801 69

The enzymatic characterization of sarcoplasmic reticulum membrane fragments from rabbit skeletal muscle presented in this paper shows that glycogen phosphorylase, as well as other enzymes (e.g., creatine kinase, myokinase, phosphorylase kinase, glycosidase, AMP-deaminase, phosphoglucomutase) are associated with these membrane preparations. Amongst these enzymes, the highest activity associated with sarcoplasmic reticulum membranes is that of glycogen phosphorylase, which is mostly (at least 95%) in its b form (dephosphorylated form), since its activity in sarcoplasmic reticulum membranes is largely dependent upon AMP. A protocol is presented to quantify the amount of phosphorylase bound to sarcoplasmic reticulum membranes from fluorimetric measurements of the content of its coenzyme, pyridoxal 5'-phosphate. The content of phosphorylase ranged from 0.03 to 0.37 mg phosphorylase per mg of membrane protein, in sarcoplasmic reticulum membrane preparations made following several of the protocols most commonly used and also depending upon the length of the starvation period of the animal before killing. We also show that dilution of sarcoplasmic reticulum membranes to 0.1-0.2 mg protein per ml in a buffer containing 50 mM Tes-KOH (pH 7.4), 0.1 M KCl and 0.25 M sucrose removes at least 95% of glycogen phosphorylase from these membrane fragments, as well as other enzymes like myokinase and glycosidase. On these grounds, we suggest to introduce a final dilution step as indicated above in protocols of sarcoplasmic reticulum membrane preparations.
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PMID:Quantification and removal of glycogen phosphorylase and other enzymes associated with sarcoplasmic reticulum membrane preparations. 807 39

The effect of intermittent high-intensity training on the activity of enzymes involved in purine metabolism and on the concentration of plasma purines following acute short-term intense exercise was investigated. Eleven subjects performed sprint training three times per week for 6 weeks. Muscle biopsies for determination of enzyme activities were obtained prior to and 24 h after the training period. After training, the activity of adenosine 5'-phosphate (AMP) deaminase was lower (P < 0.001) whereas the activities of hypoxanthine phosphoribosyl transferase (HPRT) and phosphofructokinase were significantly higher compared with pre-training levels. The higher activity of HPRT with training suggests an improved potential for rephosphorylation of intracellular hypoxanthine to inosine monophosphate (IMP) in the trained muscle. Before and after the training period the subjects performed four independent 2-min tests at intensities from a mean of 106 to 135% of VO2max. Venous blood was drawn prior to and after each test. The accumulation of plasma hypoxanthine following the four tests was lower following training compared with prior to training (P < 0.05). The accumulation of uric acid was significantly lower (46% of pre-training value) after the test performed at 135% of VO2max (P < 0.05). Based on the observed alterations in muscle enzyme activities and plasma purine accumulation, it is suggested that high intensity intermittent training leads to a lower release of purines from muscle to plasma following intense exercise and, thus, a reduced loss of muscle nucleotides.
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PMID:The effect of high-intensity training on purine metabolism in man. 812 88

Reactivity of sulfhydryl groups of human uterine smooth muscle AMP-deaminase with DTNB, and the effect of their chemical modification on kinetic and regulatory properties of the enzyme were investigated. (1), Approx. 7 and 5 sulfhydryl groups per mol of the enzyme have been shown to be accessible for DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) titration in denaturated and native AMP-deaminase, respectively. (2), Titrated groups were not homogenous; some of them reacted with DTNB much faster than others. (3), The activity of the modified enzyme was very low, and the modified enzyme manifested unusual hyperbolic saturation kinetics with the substrate. (4), Exhaustive dialysis against a buffer containing 10 mM thioethanol reactivated the modified enzyme, and restored its original regulatory properties. Experimental results obtained indicate that modified sulfhydryl groups play a significant role in the maintenance of the proper, catalytically-efficient conformation of the enzyme.
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PMID:AMP-deaminase from human uterine smooth muscle: the effect of DTNB treatment on kinetic and regulatory properties of the enzyme. 834 24

In solutions of high ionic strength, native titin-2, a large extractable fragment of the sarcomere matrix protein titin, appears as extremely long, flexible, and slender beaded strings. We report here that in solutions of lower ionic strength near neutral pH, titin-2 assembles into higher-order aggregates with surface projections. Solid phase binding assays show that two myosin-binding proteins, C-protein and AMP-deaminase, are also titin-binding proteins. Both proteins decorate titin aggregates, producing filaments of more uniform appearance. Numerical Fourier transforms of these decorated aggregates show approximately 12-nm periodicities. The interaction of titin with myosin-associated proteins such as C-protein may take part in the anchoring mechanism that prevents the stretching and extension of titin filaments in the A band.
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PMID:Filamentous aggregates of native titin and binding of C-protein and AMP-deaminase. 834 8


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