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)

Immune deficiency is characteristic of alcoholic subjects. These subjects usually show altered lymphocyte function. We determined the activities of adenosine deaminase (ADA) and ecto-5'-nucleotidase (ecto-5'N) in lymphocytes from 54 subjects: 15 healthy controls, 28 non-cirrhotic alcoholics, 8 alcoholic cirrhotics and 3 non-alcoholic cirrhotics. Whereas ADA activity was the same for all 54 subjects, ecto-5'N activity was in general lower in alcoholic subjects after cessation of alcohol intake. Following alcohol intoxication, however, ecto-5'N activity increased. The decrease of ecto-5'N activity in alcoholic subjects might be explained by shedding of the ecto-enzyme and alteration of lymphocyte subpopulations. We observed decreased mitogenic-induced lymphoblastic transformation in 3 patients with cirrhosis. All other subjects (including healthy controls) had normal mitogenic-induced blastogenesis. Interestingly, following alcohol intake, non-stimulated lymphoblastic transformation increased, leading to an apparently decreased stimulation index.
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PMID:[Purine metabolism and blastogenesis in lymphocytes of alcoholic subjects]. 299 40

Rat brain adenosine deaminase (E.C. 3.5.4.4.) was purified 667-fold from the supernatant fraction by the following techniques: heat treatment (60 degrees C), fractionation with ammonium sulfate, column chromatography on DEAE-Sepharose, and preparative gel electrophoresis. The purified enzyme was homogeneous by the criterion of polyacrylamide disc gel electrophoresis and isoelectric focusing. Amino acid composition is given. The isoelectric point of the enzyme (5.2) was determined by isoelectric focusing on agarose. The apparent molecular weight was estimated to be 39,000 (Stokes Radius [Rs] = 27.3 A) using a calibrated Sephacryl S-300 column. The study of the influence of the temperature on the initial reaction rates allowed calculation of Ea (8.9 Kcal/mole) and delta H (5.0 Kcal/mole) values. The variation of V and Km with pH suggests the existence of a sulfhydryl group and an imidazole group in the enzyme-substrate complex. The enzyme had a Km (adenosine) of 4.5 X 10(-5) M and was inhibited by inosine, guanosine, adenine, and hypoxanthine but not by other intermediates of purine metabolism. None of the inhibitors were active as substrates. The enzyme was also inhibited by dimethyl sulfoxide and ethanol. Inhibition by ethanol can account partially for the CNS depressant effects of levels 3 and 4 of alcohol intoxication. A number of drugs having therapeutic uses such as sedative, anxiolytic, analgesic, and relaxant are modulators of the enzyme. Among these, lidoflazine, phenylbutazone, and chlordiazepoxide are the most potent as inhibitors (Ki 30, 54, and 83 microM, respectively), whereas medazepam is the most potent as activator (Ka 0.32 mM). Thus, it is concluded that some drugs that inhibit adenosine uptake also modulate adenosine deaminase activity. Besides, since the enzyme is located extracellularly [Franco et al, 1986], these drugs can modulate the physiological effects exerted by extracellular adenosine.
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PMID:Purification and partial characterization of brain adenosine deaminase: inhibition by purine compounds and by drugs. 336 98