Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five enzymes concerned with the metabolism of adenine derivatives were assayed in seven regions of the rat brain. A region which included the hypothalamus had the highest AMP deaminase and adenosine deaminase activities, while its 5'-nucleotidase activities were relatively low. The enzymes named and also the uptake of [14C]adenine by incubated tissue samples were more active with hypothalamic than with neocortical tissues. On superfusion with glucose-bicarbonate saline after assimilating [14C]adenine, the hypothalamic tissues released about 0.2 per cent of their 14C content per minute. This release was increased fourfold with electrical excitation but the presence of 0.25 muM tetrodotoxin prevented most of this increase. The compounds released during superfusion and electrical stimulation were preponderantly hypoxanthine, inosine, and adenosine, with only small amounts of adenine nucleotides. The output of all these compounds increased during the period of stimulation and also the proportion of adenine nucleotides increased when stimulation was carried out in the presence of tetrodotoxin. The output of the nucleotides and adenosine increased more promptly when stimulated than did that of the other compounds named. The results are discussed in terms of the metabolic roles of the enzymes concerned. and in relation to whether the enzymes are acting on intracellular or extracellular substrates.
 ...
PMID:The metabolism of adenine derivatives in different parts of the brain of the rat, and their release from hypothalamic preparations on excitation. 126 67

Extracellular adenosine has the potential to influence many aspects of target cell metabolism. The present study has determined the endogenous levels of adenosine in the pregnant mouse uterus and developing embryo-decidual unit with respect to the expression of two key enzymes of adenosine metabolism, 5'-nucleotidase (5'-NT; EC 3.1.3.5) and adenosine deaminase (ADA; EC 3.5.4.4). To measure adenosine levels, nucleoside extracts were etheno-derivatized and quantitated by high-performance liquid chromatography-fluorescence detection (0.03 pmol/mg protein sensitivity). Adenosine levels were determined to be 0.18 nmol/mg protein in the nonpregnant uterus; however, two statistically significant changes were identified in the pregnant uterus: (1) a periimplantation surge between day 3 (0.24 nmol/mg protein) and day 5 (0.59 nmol/mg protein) of gestation (plug day 0; implantation day 4); and (2) an early postimplantation decline between day 6 (0.54 nmol/mg protein) and day 7 (0.10 nmol/mg protein). The periimplantation adenosine surge coincided with uterine expression of 5'-NT, an enzyme which catalyzes the irreversible dephosphorylation of 5'-AMP to adenosine. 5'-NT expression was shown by Northern blot analysis to peak in the embryo-decidual unit on day 5 of gestation and then to decline through day 9; transcripts remained elevated in the placenta between day 9 and day 13 (the latest day examined in this study). By use of specific enzyme histochemistry, most 5'-NT activity was localized to the primary decidual zone on day 5. This expression subsequently declined during regression of the primary decidua; however, 5'-NT appeared on giant trophoblast (days 7-13) and the metrial gland (days 11-13). Other purine catabolic enzymes degrading AMP (adenylate deaminase) or generating adenosine (S-adenosylhomocysteine hydrolase) were not detected in the embryo-decidual unit suggesting that the net flux of utero-placental AMP catabolism proceeds with adenosine as an intermediate, this being the major pathway of adenosine formation. The sharp drop in adenosine levels between day 6 and day 7 coincided with a rise in the activity and mRNA expression of ADA, an enzyme which catalyzes the irreversible deamination of adenosine to inosine. ADA was previously localized to the secondary decidual zone (days 6-11), secondary giant cells (days 7-13), and spongiotrophoblasts (days 8-13) in the mouse (Knudsen et al., 1991). Results of developmental Northern blot analysis demonstrated a direct correlation of relative 5'-NT/ADA mRNA band intensity to adenosine content between day 4 and day 9 of gestation, suggesting that the local availability of adenosine in the antimesometrium is dependent upon the distribution of these enzymatic activities.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Adenosine levels in the postimplantation mouse uterus: quantitation by HPLC-fluorometric detection and spatiotemporal regulation by 5'-nucleotidase and adenosine deaminase. 142 25

Adenosine produced from 5'-AMP has been proposed as a mediator of intrinsic renal regulation. The rates of 5'-AMP and adenosine metabolism are dependent on the activities of enzyme involved in purine metabolism. The activities of adenosine kinase (AK), adenosine deaminase (ADA), 5'-nucleotidase (5'-NT), AMP deaminase, xanthine oxidase and purine nucleoside phosphorylase were measured in cytosolic and membrane fractions from glomeruli, cortical tubules, medullary thick ascending limb of Henle (MTAL) and collecting duct prepared from rat kidney by combinations of sieving and sucrose density gradient centrifugation techniques. In the cytoplasm of glomeruli cells, the activity ratios of ADA/AK and AMP deaminase/5'-NT were 70 and 2.4, respectively. The highest activity of 5'-NT was found in membrane fractions of cortical tubules where it was equally distributed between luminal and antiluminal membranes. Membrane fractions of MTAL did not contain detectable amounts of adenosine deaminase activity. The highest activity of xanthine oxidase and purine nucleoside phosphorylase was in the cytoplasm fraction of glomeruli. These results suggest that deamination of AMP and adenosine may be favored in the cytoplasm of glomeruli cells. In contrast, in the extracellular space of glomeruli and especially in the cortical tubule, AMP can be converted preferentially to adenosine by 5'-NT.
 ...
PMID:The distribution of enzymes involved in purine metabolism in rat kidney. 161 Aug 88

Saturation and inhibition kinetics data for rat liver ADP-ribose pyrophosphatase (EC 3.6.1.13) were obtained from progress curves initiated by the addition of substrate and recorded spectrophotometrically until the end point was reached. The hydrolysis of ADP-ribose was coupled to either alkaline phosphatase and adenosine deaminase or AMP deaminase. The validity of the approach was shown because: (i) the coupled hydrolysis of ADP-ribose was essentially irreversible; (ii) ADP-ribose pyrophosphate was stable at 37 degrees C in the conditions needed for the assay; and (iii) accumulated reaction products did not inhibit detectably in the conditions of the assay. In addition, several identical progress curves could be successively recorded by repetition of the addition of substrate. In that way it was possible to carry out complete inhibition studies by increasing the inhibitor concentration between successive substrate additions. Studying the inhibition by high D-ribose concentrations, meaningful results could be obtained at four different inhibitor concentrations in a single reaction mixture, which represented a great saving of enzyme preparation with respect to what would be needed in an equivalent initial rate study.
 ...
PMID:Enzyme saturation and inhibition kinetics studied from multiple progress curves recorded spectrophotometrically from single reaction mixtures for ADP-ribose pyrophosphatase. 164 14

Phosphatidylcholine secretion in type II pneumocytes can be stimulated by P1 (adenosine) and P2 (ATP) purinoceptor agonists. The effect of adenosine is mediated by the A2 subtype of the P1 receptor. The A1 subtype is inhibitory. We examined the influence of ATP and the A2 agonist 5'-(N-ethylcarboxyamido)adenosine (NECA) on phosphatidylcholine secretion in primary cultures of rat type II cells. The stimulatory effects of ATP and NECA were less than additive, suggesting a common mechanism of action. NECA and ATP both caused a rapid increase in cAMP, and the combination enhanced this even further. ATP promoted inositol trisphosphate (IP3) formation, whereas NECA did not. The effect of ATP on adenosine 3',5'-cyclic monophosphate (cAMP) but not on IP3 was abolished by a P1 antagonist, and such antagonists diminished its effect on secretion by as much as 75%. The potency orders of ATP analogues in increasing formation of cAMP and IP3 were different. The effects of the ATP analogues on phosphatidylcholine secretion were also inhibited by the P1 antagonists, with the greatest degree of inhibition being observed with the analogue that increased cAMP to the greatest extent. The effect of ATP on secretion was not diminished by either adenosine deaminase (previous data) or AMP deaminase showing that the effects of ATP were not mediated by its metabolism to the P1 agonists adenosine or AMP. These data show that ATP acts at both A2 and P2 receptors but that most of its effects on phosphatidylcholine secretion are mediated by the A2 receptor.
 ...
PMID:A2 and P2 purine receptor interactions and surfactant secretion in primary cultures of type II cells. 165 64

6-Methoxypurine arabinoside (ara-M) exhibits potent activity against varicella-zoster virus (VZV) as a result of ara-M's anabolism to the triphosphate of adenine arabinoside (ara-ATP) in VZV-infected cells. The adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) enhanced the formation of ara-ATP by inhibiting ara-M demethoxylation. In contrast, deoxycoformycin and coformycin, inhibitors of both adenosine deaminase and AMP deaminase, blocked the formation of ara-ATP and reversed the anti-VZV activity of ara-M. These results indicate that after the initial phosphorylation of ara-M by the VZV-coded thymidine kinase, the monophosphate is demethoxylated by AMP deaminase to form ara-IMP, which is converted to ara-ATP by the sequential actions of the cellular adenylosuccinate synthetase, adenylosuccinate lyase, and nucleotide kinases.
 ...
PMID:Anabolic pathway of 6-methoxypurine arabinoside in cells infected with varicella-zoster virus. 166 24

The present study deals with the effect of atrazine on nitrogen metabolism in the liver and brain of fish. Significant changes were seen in the levels of proteins, free amino acids, ammonia, urea, glutamine and the activity levels of proteases, glucogenic aminotransferases, branched-chain aminotransferases, glutamate dehydrogenase, glutaminase, arginase, AMP deaminase and adenosine deaminase in both the tissues of fish exposed to sublethal concentration of atrazine. The study reflects a shift in nitrogen concentration of atrazine. The study reflects a shift in nitrogen metabolism in the tissues of fish for efficient mobilization of end products of protein catabolism as a consequence of atrazine.
 ...
PMID:Modulations in nitrogen metabolism in the hepatic and neuronal tissues of fish, Tilapia mossambica exposed to atrazine. 185 31

At sublethal concentrations, cypermethrin caused a decrease in total proteins and an increase in free amino acids, protease, alanine aminotransferase and aspartate aminotransferase in liver, brain and gill tissues of Tilapia mossambica. Nitrogen metabolic profiles like ammonia, urea and glutamine were also elevated in all the tissues as a consequence of cypermethrin toxicity. Glutamate dehydrogenase, AMP deaminase and adenosine deaminase activity was also increased in the present study.
 ...
PMID:Cypermethrin induced changes in nitrogen metabolism of fish, Tilapia mossambica. 187 79

The effect of aminophylline administered intravenously in dose 250 mg on plasma oxypurines (hypoxanthine and xanthine) concentration as well as on plasma adenosine deaminase activity and plasma AMP deaminase activity was studied in 17 patients with bronchial asthma or chronic cor pulmonale. Initial plasma oxypurines concentration was 47.5 +/- 10.4 mumol/l and one hour after aminophylline administration decreased significantly (p less than 0.001) to the value 40.3 +/- 8.8 mumol/l. Plasma adenosine deaminase activity increased significantly from 4.74 +/- 2.3 IU to 6.9 +/- 2.77 IU (p less than 0.01), while plasma AMP deaminase activity did not change. The above results suggest indirectly that intravenous administration of aminophylline decreases serum adenosine concentration in studied patients.
 ...
PMID:[The effect of aminophylline on plasma oxypurines in patients with bronchial asthma or cor pulmonale]. 188 28

1. A rapid method for the determination of AMP and IMP by HPLC is described. 2. Its application to the assay of AMP deaminase allows the specific determination of enzyme activities in crude extracts, eliminating any interference by other enzyme systems (5'-nucleotidase and adenosine deaminase). 3. The method was routinely used for the determination of the AMP deaminase activity in the muscles of marine animals.
 ...
PMID:A specific AMP deaminase assay and its application to tissue homogenates. 195 22


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>