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

Synthesis and biological activities of 12 analogs of N6-benzyladenosine are described. The compounds were prepared by two methods: (1) direct alkylation of adenosine with an appropriately substituted benzyl bromide to give the N1-substituted derivative which was then rearranged in base to give the N6-substituted compound, and (2) by nucleophilic displacement of chlorine in 6-chloropurine ribonucleoside, 6-chloro-2-aminopurine ribonucleoside, and 6-chloro-2-aminopurine with an amine. These analogs were examined for their growth inhibitory effect in cultured leukemic cells and also for their effect on adenosine aminohydrolase activity. N6-p-Nitrobenzyladenosine and its 2'-deoxy analog were competitive inhibitors (K1 65, 22 MUM). The 2-amino-N6-p-nitrobenzyladenine and its ribonucleoside were found to be noncompetitive inhibitors of adenosine aminohydrolase. In cultured L1210 leukemia, 2-amino-6-p-nitrobenzylaminopurine and the corresponding ribonucleoside were better growth inhibitors than N6-benzyladenosine, while N6-p-nitrobenzyladenosine, its 2'-deoxy analog, and N6-p-fluorobenzyladenosine were as active as N6-benzyladenosine.
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PMID:Synthesis and biological activities of some N6-(nitro- and -aminobenzyl)adenosines. 105 53

Anti-adenosine antibodies were produced in rabbits immunized with N6-carboxymethyladenosine conjugated to methyl albumin. 125I-N6-Aminobenzyladenosine was synthesized and used as a high-specific-activity, high-affinity ligand. A radioimmunoassay (RIA) was developed that can detect 6.25 nM (312.5 fmol) of underivatized adenosine and cross-reacts less than 0.02% with adenine nucleotides and guanosine and not at all with 1 mM inosine. The sensitivity of the RIA can be increased to a detection limit of 0.125 nM (6.25 fmol) by derivitizing samples with benzyl bromide to form N6-benzyladenosine. The assay was adapted to an automated RIA procedure. Assay precision was increased by: (i) inhibiting slight adenosine deaminase activity present in anti-sera; (ii) treating buffers and albumin used in the RIA with charcoal to remove contaminating adenosine; and (iii) correcting for a small but variable component of immunoreactivity not attributable to adenosine. A second antibody prepared with a 2',3'-disuccinyladenosine-albumin conjugate was also found to detect some non-adenosine-mediated immunoreactivity in plasma samples. Immunointerference in human plasma was eliminated in samples treated with ZnSO4/Ba(OH)2 or partially purified over C18 Sep Paks to remove nucleotides and assayed after sample benzylation or succinylation. Human blood was mixed with a novel "stop" solution that was optimized to inhibit adenosine formation from AMP by greater than 99% and to inhibit adenosine uptake into red cells and degradation by greater than 94%. Human plasma/stop solution was assayed by RIA and HPLC with equivalent results.
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PMID:The precise radioimmunoassay of adenosine: minimization of sample collection artifacts and immunocrossreactivity. 163 11

Bacteriological diagnosis of tuberculosis in childhood is often unsuccessful owing to the difficulty in obtaining suitable specimens. Many attempts have been made to diagnose tuberculosis immunologically but with very limited success. Positive tuberculin reactions may be the result of nonspecific sensitization while negative reactions occur in undernourished children. Serodiagnostic tests suffer from problems of specificity, even when very specific antigens are used, and are often least helpful in diagnostically difficult cases. Detection of antigen has proved to be of more value, especially with clean specimens such as cerebrospinal and pleural fluids. Detection of specific components of Mycobacterium tuberculosis by linked gas chromatography and mass spectroscopy is very sensitive and specific but the equipment is very costly. Detection of specific DNA sequences of M. tuberculosis in specimens by use of labelled 'DNA probes' is rather insensitive although the sensitivity may be increased greatly by use of the polymerase chain reaction to amplify small amounts of the specific DNA. Non specific indicators of tuberculosis are generally unhelpful although the bromide partition test and assay of the enzyme adenosine deaminase in cerebrospinal fluid appear to be of value in the diagnosis of tuberculous meningitis. More research is required to develop a simple, specific and automated test for tuberculosis in childhood.
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PMID:New approaches to the diagnosis of tuberculosis in childhood with special reference to neurotuberculosis. 212 31

A number of different biochemical and serological tests have been described recently for the early and accurate diagnosis of tuberculous meningitis. None of these tests has yet gained widespread acceptance in clinical medicine or in microbiology laboratories. To investigate this problem we evaluated adenosine deaminase activity (ADA), an enzyme linked immunosorbent assay (ELISA) that detects antibody to antigen 5 of Mycobacterium tuberculosis, and the radioactive bromide partition test (BPT) in the cerebrospinal fluid (CSF). Cerebrospinal fluid specimens from children with tuberculous, pyogenic, and viral meningitis as well as from patients with pulmonary tuberculosis without meningitis and from controls with normal CSFs were included inn the study. In addition, we estimated ADAs in serum samples from selected children in these groups. The sensitivity and specificity of the three tests evaluated in the CSF were: ADA assay 73% and 71%; BPT 92% and 92%; and ELISA for antibody to antigen 5, 53% and 90%, 40% and 94%, and 27% and 100%, respectively, at tires of more than or equal to 1:20, 1:40, and 1:80. The serum ADA was lower (11.0 +/- 6.15 IU/l) in children with tuberculous meningitis when compared with those with pulmonary tuberculosis alone (25.8 +/- 20.9 IU/l). The BPT was found to be the most reliable test in the early differentiation of tuberculous from other causes of meningitis and remained abnormal for a period of up to five months after the beginning of treatment. Accordingly, we believe that the BPT should be used in conjunction with bacterial and fungal antigen detection systems for the initial differentiation of clinically suspicious tuberculous meningitis from Gram or culture negative cases, or both, of bacterial and fungal meningitis.
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PMID:Evaluation of adenosine deaminase activity and antibody to Mycobacterium tuberculosis antigen 5 in cerebrospinal fluid and the radioactive bromide partition test for the early diagnosis of tuberculosis meningitis. 308 96

2-Bromo-2'-deoxyadenosine (BdA) is one of a group of recently synthesised halogenated deoxyadenosine analogues that are relatively resistant to inactivation by adenosine deaminase (ADA). Its activity has been studied in human acute myeloid leukemia (AML) in vitro. In these studies BdA behaved as a cycle-active, phase-active agent that blocked cells at the G1-S transition. It did not exhibit significant cross-resistance with cytosine arabinoside (Ara-C) in either clinical AML samples (from patients who exhibited Ara-C resistance in vivo) or in HL60 in which Ara-C resistance had been induced in vitro. Deoxycytidine kinase levels were not reduced in resistant lines. Erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an adenosine deaminase (ADA) inhibitor, with BdA produced a simple additive response without the dramatic synergism reported when it is used with deoxyadenosine. This is consistent with the idea that BdA is a poor substrate for ADA. This group of compounds warrants further investigation to determine their suitability for clinical use, especially in situations where Ara-C resistance is likely to be a problem.
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PMID:Lack of cross-resistance between cytosine arabinoside and a new halogenated nucleoside analogue, 2-bromo-2'-deoxyadenosine in human acute myeloid leukaemia cells. 349 52

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).
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PMID:Synthesis, structure, and biological activity of certain 2-deoxy-beta-D-ribo-hexopyranosyl nucleosides and nucleotides. 358 3

Because of the importance of adenosine deaminase (ADA) in brain function, a histochemical method for visualizing the enzyme in various areas of the human neuraxis was devised, using an MTT [3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyltetrazolium bromide] method and glutaraldehyde fixation. Controls consisted of preincubation without the substrate, incubation with omission successively of the substrate, MTT tetrazolium, purine nucleoside phosphorylase (PNP), xanthine oxidase (XO), NaCl, boiling for 20 min prior to fixation and incubation, and of incubation of sections with two powerful inhibitors of the enzyme, i.e., 2'-deoxycoformycin and EHNA [erythro-9-(2-hydroxy-3-nonyl)adenine.HCl]. The positive reaction consisted of the deposition of brownish-purple granules, as well as a diffuse nongranular reaction in the cytoplasm of neurons and glial cells, and in the interstitial spaces. Sections from 15 different areas in four brains were examined by this method. This is the first time that adenosine deaminase has been demonstrated histochemically in the nervous system of humans or of any other species.
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PMID:Histochemical demonstration of adenosine deaminase in the human neuraxis. Preliminary observations. 404 5

Dextran-linked adenosine deaminase (EC 3.5.4.4) has been prepared. The polymer-linked enzyme possesses an optimal enzymatic activity of 27 units/mg immobilized protein (non-bound enzyme: 200 units/mg protein). Support-bound adenosine deaminase (4.5 microgram protein/mg dextran) shows an enhanced heat stability, a moderately increased Km, and a decreased V value compared to those of the free enzyme. The pH dependences of V and pKm values of dextran-linked adenosine deaminase show only two inflection points compared to three for the free enzyme, which are equivalent to the pK values of the enzyme. Since the missing third inflection point (pH 9.8) can be assigned to the pK value of the epsilon-amino group of lysyl residues, it can be concluded, that immobilization of adenosine deaminase on cyanogen-bromide-activated dextran took place via these lysyl residues. The remaining pK values found from the other inflection points are moderately shifted owing to the altered secondary structure. From the temperature dependence of the enzymatic activity, a 40% decrease of the activation energy of the support-bound enzyme was found, indicating diffusion controlled deamination. The immobilization of adenosine deaminase results in a fluorescence quenching of 80%, without shifting the ultraviolet maximum of the emission spectrum. As already shown for unmodified dextran, the matrix of polymer-linked adenosine deaminase is degradable by a bacterial endodextranase (EC 3.2.1.11).
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PMID:Adenosine deaminase covalently linked to soluble dextran. The effect of immobilization on thermodynamic and kinetic parameters. 617 33

Dextran-bound adenosine, inosine, and nebularine have been prepared by carbodiimide coupling of their 2',3'-O-(4-carboxyethyl-1-methylbutylidene) cyclic acetal derivatives to 6-aminohexyldextran or 12-aminododecanyldextran. The latter polymers were prepared by cyanogen-bromide activation of dextran T80 followed by reaction with 1,6-diaminohexane or 1,12-diaminododecane. A high CNBr concentration leads to high-molecular-weight material, probably due to cross-linking, accompanied by a decrease in the digestion velocity using endo-dextranase from Penicillium species (EC 3.2.1.11). The dextran-bound nucleosides, as well as the nucleoside 2',3'-O-(4-ethoxycarbonyl-1-methylbutylidene) acetal derivatives, were tested as substrates and inhibitors for adenosine deaminase. The Km of the adenosine acetal ester is identical to that of adenosine which shows that acetalation does not hinder complex formation. Since the maximum velocity of deamination is decreased fourfold, the modified substrate does not fit as well as the nucleoside. The polymer-bound acetals show a 3-8-fold increase of Km or Ki and unchanged V compared to the corresponding acetals while dextranase digestion of the support does not alter the kinetic data. This indicates that the length of the polysaccharide chain does not interfere either with the complex formation or with the catalytic activity of the modified substrate. Since the activation energies of the deamination reactions of adenosine, its acetal ester, and dextran-linked adenosine are all similar (29.8-32.3 kJ mol-1) it is concluded that no diffusion control of the enzymatic reaction results from the binding of the nucleoside acetals to dextran T80.
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PMID:Dextran-linked purine nucleosides as substrates and inhibitors of adenosine deaminase. 618 16

Bromide partition tests were performed on 58 children with suspected tuberculous meningitis (TBM). CSF adenosine deaminase activity (ADA) was measured at the same time. Four of the 33 patients with a final diagnosis of TBM had false-negative bromide partition ratios and 5 had false-negative CSF ADA levels. One of the 25 patients in whom TBM was excluded had a false-positive ratio and 4 had false-positive CSF ADA levels. The difference between the two tests was not significant. Both provide valuable evidence for or against a diagnosis of TBM.
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PMID:The bromide partition test and CSF adenosine deaminase activity in the diagnosis of tuberculosis meningitis in children. 711 20


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