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)

The association of adenosine deaminase (ADA) deficiency with immunodeficiency disease has emphasized the importance of this purine metabolic enzyme for human lymphocyte growth and function. This report describes the natural occurrence of ADA deficiency in a human histiocytic lymphoma cell line, DHL-9. The minimal ADA activity in DHL-9 extracts, 0.028 nmol/min/mg protein, was less than 50% of the activity in two B-lymphoblastoid cell lines from ADA-deficient patients and was resistant to the potent ADA inhibitor deoxycoformycin. A sensitive radioimmunoassay failed to detect immunoreactive ADA in DHL-9 cells. Moreover, in DHL-9 cells, deoxycoformycin did not augment either the growth-inhibitory effects of adenosine and deoxyadenosine or the accumulation of deoxyadenosine triphosphate from deoxyadenosine. When compared to six other human hematopoietic cell lines, DHL-9 had 5.6-fold-higher levels of adenosylhomocysteinase. Chromosome 20, which bears the structural gene for ADA and adenosylhomocysteinase, was diploid and had a normal Giemsa banding pattern. The parental DHL-9 cell line was used for the selection and cloning of secondary mutants deficient in deoxycytidine kinase and adenosine kinase.
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PMID:Characterization of an adenosine deaminase-deficient human histiocytic lymphoma cell line (DHL-9) and selection of mutants deficient in adenosir kinase and deoxycytidine kinase. 630 63

Several nucleoside analogues, some of which are potent inactivators of isolated S-adenosylhomocysteinase (AdoHcyase), were tested with respect to their effect on intracellular AdoHcyase and S-adenosylhomocysteine (AdoHcy) catabolism in intact rat hepatocytes. Among the analogues tested, 9-beta-D-arabinofuranosyladenine and 9-beta-D-arabinofuranosyl-3-deazaadenine were the most potent inactivators of intracellular AdoHcyase. Compounds like 2-chloroadenosine and carbocyclic adenosine are extremely efficient inactivators of the isolated enzyme, but these nucleosides exerted only a limited effect on the enzyme in intact hepatocytes. Only a moderate effect was observed with 2-chloro-3-deazaadenosine and 2'-deoxyadenosine, and a high concentration of 5'-deoxy-5'-methylthioadenosine was required to inactivate the enzyme. There was a correlation between inactivation and accumulation of AdoHcy. Carbocyclic-3-deazaadenosine caused no inactivation of AdoHcyase in liver cells but caused a massive accumulation of AdoHcy, suggesting that this analogue functions as a reversible inhibitor of the enzyme. Residual enzyme activity was observed with all the nucleoside analogues tested. The intracellular enzyme inactivated in the presence of 2'-deoxyadenosine and 9-beta-D-arabinofuranosyladenine was readily recovered when the cells were transferred to fresh medium containing adenosine deaminase, but reactivation of the enzyme activity after treatment of the cells with 2-chloroadenosine and 5'-deoxy-5'-methylthioadenosine was also observed. The inactivation of intracellular enzyme induced by 2-chloro-3-deazaadenosine, 9-beta-D-arabinofuranosyl-3-deazaadenine, and carbocyclic adenosine was essentially irreversible under the conditions of the experiments. Factors determining the effect of nucleoside analogues on intracellular AdoHcyase are discussed.
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PMID:Inactivation and reactivation of intracellular S-adenosylhomocysteinase in the presence of nucleoside analogues in rat hepatocytes. 646 91

An inherited deficiency of adenosine deaminase (Ado deaminase; adenosine aminohydrolase, EC 3.5.4.4) causes severe combined immunodeficiency disease in humans. A similar deficiency in purine nucleoside phosphorylase (Puo phosphorylase; purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) engenders a selective cellular immune deficit. To elucidate the possible metabolic basis for the contrasting immunologic phenotypes, we compared the toxicity toward mature resting human lymphocytes of the Ado deaminase substrates deoxyadenosine and adenosine and the Puo phosphorylase substrate deoxyguanosine. When Ado deaminase was inhibited, micromolar concentrations of deoxyadenosine progressively killed nondividing helper and suppressor-cytotoxic T cells, but not B cells. The toxicity required phosphorylation, with subsequent dATP formation. The deoxyadenosine analogs 2-chlorodeoxyadenosine, 2-fluorodeoxyadenosine, and adenine arabinonucleoside also killed resting T cells. Cell death was unrelated to inhibition of adenosylhomocysteinase (EC 3.3.1.1) but was preceded by a gradual decline in ATP levels. As much as 1 mM deoxyguanosine did not impair resting lymphocyte viability, despite the synthesis of dGTP. The combination of 200 microM adenosine plus 500 microM homocysteine thiolactone killed dividing lymphocytes but had no discernible toxic effect toward resting T cells, which accumulated adenosylhomocysteine over a 4-hr period but thereafter excreted the nucleoside into the culture medium. The different clinical syndromes associated with genetic deficiencies of Ado deaminase and Puo phosphorylase may be explained by the ability of dATP to kill mature resting T lymphocytes by depleting ATP levels.
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PMID:Possible metabolic basis for the different immunodeficient states associated with genetic deficiencies of adenosine deaminase and purine nucleoside phosphorylase. 680 16

To evaluate for selective toxicity of S-adenosylhomocysteine toward cultured lymphoblasts, cytotoxicity was correlated with S-adenosyl-L-homocysteine accumulation in cultured human B-lymphoblasts (MGL-8) and T-lymphoblasts (MOLT-4) during adenosine deaminase inhibition with EHNA. The addition of adenosine increased intracellular S-adenosylhomocysteine levels and decreased the growth of B-lymphoblasts, with an estimated ID50 of 50 micro M. These changes were enhanced by the addition of homocysteine thiolactone. The addition of deoxyadenosine, even with homocysteine thiolactone, had no effect in B-lymphoblasts. The addition of deoxyadenosine potently decreased the growth of T-lymphoblasts, with an estimated ID50 of 16 micro M, and increased intracellular S-adenosylhomocysteine concentrations. The changes were enhanced with the addition of homocysteine thiolactone. T-lymphoblasts cultured with adenosine showed only modest increases in intracellular S-adenosylhomocysteine levels but did have a substantial decrease in growth. These changes were not substantially modified by the addition of homocysteine thiolactone. S-adenosyl-L-homocysteine hydrolase activity did not correlate with cytotoxicity or S-adenosyl-L-homocysteine accumulation in B- or T-lymphoblasts. These data suggest that selective S-adenosyl-L-homocysteine accumulation and toxicity in B-lymphoblasts provide a potential mechanism for the B-lymphocyte defect in adenosine deaminase deficiency. The accumulation of S-adenosylhomocysteine in T-lymphoblasts and the associated cytotoxicity provide evidence to implicate this mechanism as contributing to the T-cell disorders in inherited or acquired adenosine deaminase deficiency.
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PMID:S-Adenosylhomocysteine accumulation and selective cytotoxicity in cultured T- and B-lymphocytes. 698 Feb 50

S-adenosyl-L-homocysteine hydrolase catalyses the synthesis of S-adenosyl-homocysteine (AdoHcy) from adenosine (Ado) and L-homocysteine (L-Hcy) in the absence of other enzymes, such adenosine deaminase, using Ado or L-Hcy as a substrate. Studies concerning the effect of substrates and enzyme concentrations with enzyme from beef liver, an inexpensive enzyme source, allowed the determination of the smallest amount of enzyme leading to total conversion to AdoHcy for the highest Ado and L-Hcy concentrations. Washing out the blood, homogenization of beef liver slices at pH 4.9 and precipitation with between 40% and 50% saturated (NH4)2SO4 eliminated contamination of tissue by blood adenosine deaminase. This enzyme preparation transforms Ado only into AdoHcy in the presence of L-Hcy. In a 1 1 final volume, an amount of enzyme preparation corresponding to at least 18.5 mg of fresh liver causes the total transformation of 60 mM Ado in the presence of 90mM L-Hcy after 40 hours incubation at 37 degrees C and pH 6.8. After purification by two crystallizations, the AdoHcy yield, based upon the Ado incubated, is about 80% of theory (1.0 g of AdoHcy per g of fresh beef liver).
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PMID:S-adenosyl-L-homocysteine: simplified enzymatical preparation with high yield. 717 Mar 3

An assay method has been developed for the purine catabolic enzymes adenosylhomocysteinase, adenosine deaminase (ADA), purine-nucleoside phosphorylase (PNP), and urate oxidase in mice. The assay links H2O2 produced during purine catabolism to the production of a dye complex. The assay method has been developed for ADA and PNP in erythrocytes and for all four enzymes in liver. The assay is cheap, sensitive, and easy to perform. The dye complex absorbs in the visible range, negating the need for an expensive ultraviolet spectrophotometer and allowing the use of an autoanalyzer.
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PMID:Development of an assay method for purine catabolic enzymes in the mouse and its adaptation for use on an autoanalyzer. 785 44

1. Specific activities of adenosine deaminase, purine nucleoside phosphorylase, adenosine kinase, 5'-nucleotidase, S-adenosyl-L-homocysteine hydrolase, AMP deaminase, adenine phosphoribosyl transferase, and hypoxanthine phosphoribosyl transferase were analyzed in human CD4 T-lymphocyte subsets. 2. CD4 Leu 8- (helper/inducer) and CD4 Leu 8+ (suppressor/inducer) subpopulations were obtained by panning or fluorescence activated cell sorting techniques using specific monoclonal antibodies. 3. A 45% decrease of 5'-NT AMP activity in the CD4 Leu 8- cells (suppressor/inducer) compared with CD4 total cell population. 4. No statistical significant differences in enzyme activity were found between the subsets analyzed in other purine enzymes. 5. These results suggest that the distribution of purine metabolic enzymes is homogeneous in CD4 Leu 8- and CD4 Leu 8+ T-lymphocyte subpopulations.
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PMID:Analysis of purine metabolic enzymes in human CD4 Leu 8- and CD4 Leu 8+ lymphocyte subpopulations. 844 17

We investigated the protein profiles of variously aged rat astrocytes in response to oxidative stress. After H2O2-exposure of cells at 100 microM for 30 min, the relative intensity of ten protein spots changed on two-dimensional (2-D) gels compared with control gels after silver staining. Matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) analysis after in-gel digestion revealed that six of these spots corresponded to three kinds of proteins, each of which was composed of a protein and its modified form with a different isoelectric point (pI). These three proteins were identified as peroxiredoxins (PRDXs) II and III, and calpactin I light chain (p11). H2O2-exposure increased the intensity of the spot with lower pI and simultaneously decreased that of the spot with higher pI for both PRDXs II and III. In addition, the expression of annexin VII, S-adenosyl-L-homocysteine hydrolase, elongation factor II fragment (EF-II), and adenosine deaminase was increased by H2O2-exposure in astrocytes from variously aged rats. Using the Pro-Q Diamond staining, heat shock protein 60 kDa (Hsp 60) and alpha-tubulin were observed to be phosphorylated upon H2O2-exposure. While phosphorylation of alpha-tubulin was correlated positively with age, the changes in abundance of ten protein spots as described above were independent of age. These results suggest that aging does not suppress the responses aimed at limiting injury and promoting repair brought about by severe oxidative stress, and might affect cell dynamics including the formation of microtubules.
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PMID:Age-dependent variations of cell response to oxidative stress: proteomic approach to protein expression and phosphorylation. 1596 13

2-Modified aristeromycin derivatives and their related analogs were synthesized to investigate their inhibitory activity against human and Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase (PfSAHH). 2-Fluoroaristeromycin showed a strong inhibitory activity against PfSAHH selectively and complete resistance to adenosine deaminase.
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PMID:Synthesis of 2-modified aristeromycins and their analogs as potent inhibitors against Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase. 1829 95