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

---

Query: EC:3.5.4.4 (adenosine deaminase)
5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenine aminohydrolase (EC 3.5.4.2) from four species of Leishmania and from Crithidia fasciculata was examined for specific activities, affinity for substrate (adenine), and stability to heat. All were found to be strongly and non-competitively inhibited by both coformycin and deoxycoformycin, two tight-binding inhibitors of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4). Deoxycoformycin is the more potent inhibitor of the two. Neither inhibitor was active against the purine phosphoribosyltransferases. When deoxycoformycin was added to the defined growth medium containing hypoxanthine as the purine source, the growth of C. fasciculata was unaffected, but when adenine was the purine source for the organism, severe inhibition resulted. This implies that hypoxanthine is the obligatory base for nucleotide synthesis and that the adenine phosphoribosyltransferase (AMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.7) is, in some manner,idenied access to exogenous substrate.
...
PMID:Adenine aminohydrolase: occurrence and possible significance in trypanosomid flagellates. 29 Oct 31

Various enzymes in the semen of men were examined to see if any could be related to measures of fertility. Fumarase activity was highly correlated with sperm number and percentage motility. Diamine oxidase activity was higher in samples with sperm counts of less than 20 X 10(6)/ml and aperm motility of less than 20%. Monoamine oxidase, adenine deaminase and prostaglandin dehydrogenase were undetectable in significant amounts in all samples, while peroxidase and adenosine deaminase were not correlated with sperm count and motility. It is suggested that the simple spectrophotometric assays for fumarase and diamine oxidase could form the basis of a routine assessment of human semen samples for estimation of male infertility.
...
PMID:The development of a qualitative assay for male infertility from a study of enzymes in human semen. 41 Sep 26

Cell-free, dialyzed extracts from Azotobacter vinelandii rapidly dephosphorylate [U-14C]ATP to labeled ADP and AMP, which is then degraded to hypoxanthine, the end product of AMP catabolism under the experimental conditions which were used. The intermediates of the pathway from ATP to hypoxanthine have been identified by thin layer chromatography and quantitated by the 14-C content. The concentrations of intermediates present during the production of hypoxanthine are consistent with AMP nucleosidase being responsible for AMP degradation in these extracts. This result was confirmed in experiments which utilized rabbit antibody prepared against purified AMP nucleosidase. The antibody inhibited AMP nucleosidase activity in cell-free extracts but did not inhibit adenine demanase or adenosine deaminase from the same extracts. In the presence of antibody prepared against purified AMP nucleosidase, the dialyzed extracts showed a marked reduction in the production of hypoxanthine from ATP. Other enzymes which could be responsible theoretically for the conversion of AMP to hypoxanthine were not detected by standard assay procedures. These results are consistent with AMP degradation proceeding by way of AMP nucleosidase to yield adenine and ribose 5-phosphate. The adenine is then converted to hypoxanthine by adenine deaminase. Both of these enzymes were present in sufficient quantities to account for the observed rates of hypoxanthine formation. The rate of hypoxanthine formation decreases during the time course of the [U-14-C]ATP degradation experiments, even though the concentration of AMP remains high. This decrease in the rate of hypoxanthine formation as a function of time is attributed to the decreasing ATP and increasing P0-4 concentrations, since ATP is an activator of AMP nucleosidase and P0-4 is an inhibitor. These observations suggest that the in vivo activity of AMP nucleosidase could also be regulated by changes in the relative ratios of ATP:AMP:P0-4.
...
PMID:The pathway of adenylate catabolism in Azotobacter vinelandii. Evidence for adenosine monophosphate nucleosidase as the regulatory enzyme. 116 48

Profiles of the catabolism of adenine nucleotides in cultured plant cells were investigated. Adenine nucleotides, prelabelled by incubation of suspension-cultured Catharantus roseus cells with [8-14C]adenosine, were catabolized rapidly and most of the radioactivity appeared in 14CO2. Allantoin and allantoic acid, intermediates of the oxidative catabolic pathway of purines, were temporarily labelled. When the cells, prelabelled with [8-14C]adenosine, were incubated with high concentrations of adenosine, the rate of catabolism of adenine nucleotides increased. The results suggest that the relative rate of catabolism of adenine nucleotides is strongly dependent on the concentration of adenine nucleotides in the cells. Studies using allopurinol, coformycin and tiazofurin, inhibitors of enzymes involved in purine metabolism, suggest that participation of AMP deaminase and xanthine oxidoreductase in the catabolism of adenine nucleotides in plant cells. AMP deaminase was found in extracts from C. roseus cells and its activity increased significantly in the presence of ATP. In contrast, no adenosine deaminase or adenine deaminase activity was detected. Qualitative differences in the catabolic activity of AMP were observed between suspension-cultured cells from different species of plants.
...
PMID:Catabolism of adenine nucleotides in suspension-cultured plant cells. 201 71

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.
...
PMID:Purine-metabolising enzymes in Entamoeba histolytica. 287 91

Cultured promastigote and isolated amastigote forms of Leishmania mexicana mexicana have been surveyed for the presence of enzymes involved in purine metabolism. Quantitative but not qualitative differences between the enzymes of two forms were discovered. There were found to be significant differences between the enzyme content of L. m. mexicana and that reported for L. donovani. Extracts of both parasite forms of L. m. mexicana were found to have higher levels of adenine deaminase (EC 3.5.4.2) and guanine deaminase (EC 3.5.4.3) than adenosine deaminase (EC 3.5.4.4). There appeared to be two distinct nucleosidases (EC 3.2.2.1), one active on nucleosides, the other on deoxynucleosides. Phosphorylase (EC 2.4.2.1) could be detected only in the catabolic direction. Nucleotidases were present, but were more active on 3' (EC 3.1.3.6)- than 5' (EC 3.1.3.5)-nucleotides. Phosphoribosyltransferase (EC 2.4.2.7,.8 and .22) and nucleoside kinase (EC 2.7.1.20) activities were detected in both forms. Nucleotide-interconverting enzymes were found to be present, with IMP dehydrogenase (EC 1.2.1.14) being the most active. Cell fractionation experiments revealed that, in the promastigote, enzyme separation within the parasite may play an important part in regulating cellular purine metabolism.
...
PMID:Leishmania mexicana: purine-metabolizing enzymes of amastigotes and promastigotes. 298 37

By monitoring the in vivo incorporation of low concentrations of radiolabeled adenine into acid-soluble compounds, we observed the unusual accumulation of two nucleosides in Saccharomyces cerevisiae that were previously considered products of nucleotide degradation. Under the culture conditions used in the present study, radiolabeled adenosine was the major acid-soluble intracellular derivative, and radiolabeled inosine was initially detected as the second most prevalent derivative in a mutant lacking adenine aminohydrolase. The use of yeast mutants defective in the conversion of adenine to hypoxanthine or to AMP renders very unlikely the possibility that the presence of adenosine and inosine is attributable to nucleotide degradation. These data can be explained by postulating the existence of two enzyme activities not previously reported in S. cerevisiae. The first of these activities transfers ribose to the purine ring and may be attributable to purine nucleoside phosphorylase (EC 2.4.2.1) or adenosine phosphorylase (EC 2.4.2.-). The second enzyme converts adenosine to inosine and in all likelihood is adenosine aminohydrolase (EC 3.5.4.4).
...
PMID:Adenosine accumulation in Saccharomyces cerevisiae cultured in medium containing low levels of adenine. 308 89

Mobilization of the ribose moiety of purine nucleosides as well as of the amino group of adenine may be realized in Bacillus cereus by the concerted action of three enzymes: adenosine phosphorylase, adenosine deaminase, and purine nucleoside phosphorylase. In this pathway, ribose-1-phosphate and inorganic phosphate act catalytically, being continuously regenerated by purine nucleoside phosphorylase and adenosine phosphorylase, respectively. As a result of such a metabolic pathway, adenine is quantitatively converted into hypoxanthine, thus overcoming the lack of adenase in B. cereus.
...
PMID:Phosphorylase-mediated mobilization of the amino group of adenine in Bacillus cereus. 312 63

2-Deoxy-beta-D-ribo-hexopyranosyl nucleosides with adenine (2), hypoxanthine (17), guanine (23), cytosine (13), and uracil (7) as the aglycon were synthesized by the Lewis-acid catalyzed condensation of an appropriate trimethylsilylated heterocyclic base and 2-deoxy-1,3,4,6-tetrakis-O-(4-nitrobenzoyl)-beta-D-ribo-hexopyranose+ ++ (5) to provide the desired beta anomers in good yield. When the synthesis of 7 via an SN2 displacement was attempted by reaction between silylated uracil and 2-deoxy-3,4,6-tris-O-(4-nitrobenzoyl)-alpha-D-ribo-hexopyranosyl bromide (8), the major product, 1-(2-deoxy-3,4,6-tris-O-(4-nitrobenzoyl)-alpha-D-ribo-hexopyranosyl)-2,4 - pyrimidinedione (9), had retained the alpha configuration at the anomeric carbon. The structures of both anomers of 1-(2-deoxy-D-ribo-hexopyranosyl)-2,4-pyrimidinedione were assigned by single-crystal X-ray methods. The anomeric configuration and conformation of other nucleosides were determined by proton magnetic resonance analysis of the 4-nitrobenzoylated nucleosides. Nucleoside 6'-monophosphates of 7, 13, and 2 and the 4',6'-cyclic monophosphate of 2 were also prepared. All 2'-deoxy-D-ribo-hexopyranosyl nucleosides and 6'-monophosphate derivatives were tested in vitro for antiviral and antitumor activity. The guanosine analogue 23 was moderately active against HSV-2 virus. The UMP analogue, 1-(2-deoxy-6-O-phosphono-beta-D-ribo-hexopyranosyl) -2,4-pyrimidinedione (28), demonstrated moderate activity against HSV-2 and parainfluenza 3 virus and was also active against L1210 (ID50 = 39 microM) and P388 (ID50 = 33 microM) leukemic cell lines. Two compounds, 6-amino-9-(2-deoxy-beta-D-ribo-hexopyranosyl)purine (2) and 9-(2-deoxy-beta-D-ribo-hexopyranosyl)-2,6-diaminopurine (24), were substrates for adenosine deaminase (EC 3.5.4.4) with Km values of 57 and 90 microM, respectively. 6-Amino-7-(2-deoxy-beta-D-ribo-hexopyranosyl)purine, 18, was a competitive inhibitor of ADase (Ki = 0.1 mM).
...
PMID:Synthesis, structure, and biological activity of certain 2-deoxy-beta-D-ribo-hexopyranosyl nucleosides and nucleotides. 358 3

Purine-requiring mutants of Salmonella typhimurium LT2 containing additional mutations in either adenosine deaminase or purine nucleoside phosphorylase have been constructed. From studies of the ability of these mutants to utilize different purine compounds as the sole source of purines, the following conclusions may be drawn. (i) S. typhimurium does not contain physiologically significant amounts of adenine deaminase and adenosine kinase activities. (ii) The presence of inosine and guanosine kinase activities in vivo was established, although the former activity appears to be of minor significance for inosine metabolism. (iii) The utilization of exogenous purine deoxyribonucleosides is entirely dependent on a functional purine nucleoside phosphorylase. (iv) The pathway by which exogenous adenine is converted to guanine nucleotides in the presence of histidine requires a functional purine nucleoside phosphorylase. Evidence is presented that this pathway involves the conversion of adenine to adenosine, followed by deamination to inosine and subsequent phosphorolysis to hypoxanthine. Hypoxanthine is then converted to inosine monophosphate by inosine monophosphate pyrophosphorylase. The rate-limiting step in this pathway is the synthesis of adenosine from adenine due to lack of endogenous ribose-l-phosphate.
...
PMID:Metabolism of exogenous purine bases and nucleosides by Salmonella typhimurium. 492 5


1 2 3 4 Next >>

---