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)

Immobilised inosine (6a) and adenosine (6c) and their 5'-phosphates have been synthesized. Reaction of the nucleosides with ethyl levulinate, followed by saponification or phosphorylation and then saponification, gave the 2',3'-O-[1-(2-carboxyethyl)ethylidene] derivatives 3 and 4 and the corresponding 5'-phosphates 2b and 2d. 6-Aminohexylagarose (5) was severally coupled to 2b, 2d, 3, and 4 through the carboxyl groups to give the polymers 6a-d. Adenosine deaminase converts 3 into 4, and 6c into 6a. The polymers can be used as affinity resins for adenosine deaminase, which is bound more strongly to 6c than to 6a. The operational capacity of 6a for adenosine deaminase is constant at 15--25 degrees, but decreases by approximately 16% from 25 degrees to 35 degrees. The resin 6a has been used to separate adenosine deaminase from mixtures containing other enzymes, for example, guanase or alcohol dehydrogenase.
...
PMID:Substrate- and product-affinity resins for adenosine deaminase obtained by immobilisation of adenosine and inosine via 2',3'-cyclic acetal derivatives. 64 8

Incubation of isolated rat epididymal fat cells is associated with the accumulation of adenosine in the incubation medium. To more clearly define the effect of adenosine on lipolysis, isolated rat epididymal adipocytes were studied with the perifusion system. Various combinations of epinephrine, adenosine, and adenosine deaminase were perifused through the adipocytes. Exogenous adenosine, 0.001-10.0 muM, had no discernible influence upon unstimulated lipolysis; but exogenous adenosine inhibited epinephrine-sensitive lipolysis in a concentration-dependent manner. Cells perifused with 0.3 muM epinephrine plus 0.001 muM adenosine did not show any impairment of the lipolytic response to 0.3 muM epinephrine alone. Adenosine, 0.01 muM, inhibited the response to epinephrine by 50%; response to 0.3 muM epinephrine plus 0.1 muM adenosine was similar to the basal rate. Perifusion with adenosine deaminase significantly increased basal lipolysis to 30% of the epinephrine response. Adenosine deaminase and epinephrine were synergistic in stimulating lipolysis to 180% of the response to epinephrine alone. Isolated fat cells were incubated for 30 min, and the cell-free used medium was perifused through fresh fat cells. Epinephrine in used medium was less effective in promoting lipolysis than epinephrine in fresh buffer. High-pressure liquid chromatography identified adenosine in the used medium. Bovine serum albumin possessed adenosine deaminase activity but accounted for negligible conversion of adenosine to inosine. Adenosine is shown to have a modulating effect upon basal and hormone-stimulated lipolysis in the perifusion system. Sufficient endogenous adenosine (<0.01 muM) is present to maximally affect basal lipolysis. Hormone-stimulated lipolysis, although inhibited somewhat by endogenous adenosine, requires the addition of exogenous adenosine for complete inhibition.
...
PMID:Perifusion of isolated rat adipose cells. Modulation of lipolysis by adenosine. 87 2

Adenosine deaminase (adenosine aminohydrolase EC 3.5.4.4) has been purified 468,000-fold from pooled human erythrocytes. The procedure developed was used to isolate the enzyme from up to 23 liters of packed erythrocytes at one time. An easily prepared affinity column bed material employing adenosine as the ligand was used as the final step in the purification. During elution from the affinity column there was approximately a 3:1 partition of adenosine deaminase between gel bed and column buffer. There was no apparent difference in the partitioning of unresolved or partially resolved preparations of the electrophoretically different forms of the enzyme on the affinity column. Gel filtration and electrophoresis on polyacrylamide gels of increasing concentration revealed no differences in the Mr of these electrophoretically different forms. The four bands resolved by electrophoresis of the different forms on polyacrylamide gels under nondenaturing conditions yielded a single band when electrophoresis was carried out in the presence of sodium dodecyl sulfate and 2-mercaptoethanol. Partially resolved preparations of the different electrophoretic forms of adenosine deaminase also gave rise to a single band of the same mobility when electrophoresed on polyacrylamide gels under these conditions. The band had the mobility of a protein of Mr of 36,000. This Mr is approximately the same as estimated for the nondenatured enzyme.
...
PMID:Purification of human erythrocyte adenosine deaminase by affinity column chromatography. 93 20

Adenosine aminohydrolase from calf intestinal mucosa is sensitive to changes in its environment produced by small mole fractions of dimethylsulfoxide (DMSO). At a mole fraction of 0.1 where the dielectric constant is lowered from that of 78 of neat water to about 76.5, Vmax was reduced by 65% and affinity for substrate (adenosine) and the two competitive inhibitors, insine and N6-benzyladenosine, was decreased markedly. However, this decreased affinity was such that Ki/Km remained virtually constant for both inhibitors. DMSO itself showed the kinetics of a mixed inhibitor with Ki decreasing with increasing mole fraction. This cosolvent also decreased the heat stability of the enzyme which suggests that enzyme conformation is altered by DMSO. Comparison of data in the presence of DMSO with previously obtained data with dioxane shows that heat stability as well as Vmax, at a given value of dielectric constant, is independent of the amount or nature of cosolvent used to achieve that dielectric constant. However, cosolvent induced changes in Ki indicate that colligative as well as dielectric constant effects contribute to the observed changes in kinetic behavior. These experiments may be considered as models for the behavior of enzymes in the medium of lowered dielectric constant expected in the vicinity of cytoplasmic membranes. The results indicate that in such an environment, adenosine aminohydrolase would be expected to be less efficient a catalyst, but equally susceptible to product inhibition, as compared to media of dielectric constant approaching that of water.
...
PMID:Cosolvent-buffer mixtures as models for the cytoplasmic mileu: the enzymology of adenosine aminohydrolase. 98 42

Adenosine deaminase (EC 3.5.4.4., ADA) has been measured in the blast cells of 36 patients with acute lymphoblastic, acute myeloid, chronic myeloid and chronic myeloid blast crisis leukaemia. Particularly high levels were found in acute lymphoblastic and chronic myeloid blast crisis patients. The measurement of ADA may be useful diagnostically in the undifferentiated acute leukaemias and in detecting the early onset of blast crisis in chronic myeloid leukaemia. Possible reasons for the elevation of ADA in malignant cells are discussed.
...
PMID:Adenosine deaminase activity in leukaemia. 105 44

Adenosine deaminase (EC 3.5.4.4, ADA) has been assayed in lymphocytes, granulocytes and erythrocytes from 45 patients with haematological malignancies. Activities were uniformly low in lymphocytes from patients with chronic lymphocytic leukaemia. Variable, but abnormal activities were frequently found in multiple myeloma, untreated lymphoma and leukaemic reticuloendotheliosis. High values were observed in lymphocytes from patients with lymphoma during intensive combination chemotherapy. ADA levels in lymphocytes were not correlated with levels in granulocytes or erythrocytes. ADA was elevated in blasts of patients with acute lymphocytic and myelogenous leukaemias but the ranges of activities per cell were so similar that ADA assay is unlikely to be of major help in distinguishing the two diseases.
...
PMID:Adenosine deaminase activity in peripheral blood cells of patients with haematological malignancies. 106 90

Adenosine aminohydrolase from human spleen was purified 120 fold. In pH 7.3 phosphate buffer at 37 degrees, this enzyme preparation deaminated adenosine and arabinosyladenine (ara-A) with apparent values for the Michaelis constant of 40 muM and 90 muM respectively. The products of both deamination reactions, i.e., inosine and arabinosylhypoxanthine, were competitive inhibitors with Ki equal to 710 muM and 60 muM, respectively. N6-benzyladenosine and 2'-deoxy-N6-benzyladenosine were competitive inhibitors. The former was better able to inhibit ara-A than adenosine deamination, while the latter was equivalent in inhibiting deamination of these two substrates. Evidence for a naturally occurring adenosine aminohydrolase inhibitor in spleen was presented. It is suggested that benzyladenosine and deoxybenzyladenosine might potentiate ara-A chemotherapy of neoplasms and metastates in the spleen and other hemic cells.
...
PMID:Adenosine aminohydrolase from human spleen: partial purification and some kinetic properties. 107 May 12

1. Erythrocyte adenosine deaminase (EC 3.5.4.4) and purine nucleoside (inosine) phosphorylase (EC 2.4.1.1) were measured in 33 healthy controls and 43 primary gouty subjects. Adenosine deaminase activity in controls and gouty subjects was 0.373 plus or minus 0.108 and 0.457 plus or minus 0.140 A unit per 5-10-3 ml packed red cells per h, respectively. The difference was statistically significant (P less than 0.01). Mean adenosine deaminase: inosine phosphorylase (X10) in primary gout was also significantly higher than in controls (P less than 0.05). Inosine phosphorylase activities in the two groups were not significantly different. 2. When gouty patients were divided into two groups according to weight, normal weight gouty subjects had a higher adenosine deaminase activity and an increased ration of adenosine deaminase to inosine phosphorylase when compared with overweight patients (P less than 0.10). In two control groups divided according to the percentage overweight, such differences were not found. In the case of two gouty groups divided according to the existence of gouty heredity, tophi or renal impairment, adenosine deaminase and inosine phosphorylase activity in the two groups were not significantly different. The possible biochemical role of adenosine deaminase activity in primary gout is discussed.
...
PMID:Erythrocyte adenosine deaminase and purine nucleoside phosphorylase activity in gout. 111 66

Affinity chromatography has been used to purify adenosine deaminase from various sources: calf spleen, calf intestinal mucosa, chicken duodena and human erythrocytes. For this purpose a specific inhibitor, 9-(p-aminobenzyl) adenine, was synthesized and covalently joined to agarose. Adenosine deaminase is selectively retained by such an inhibitor-resin when highly impure solutions are chromatographed through it. After elution from the resin with guanylurea, a competitive inhibitor, the enzyme is homogeneous and can be recovered in yields of 80 percent or more and the same number of multiple forms of the enzyme is present in the purified preparation and in the crude extract.
...
PMID:A general method of purification of adenosine deaminase by affinity chromatography. 112 Jun 33

To evaluate the regulation of adenine nucleotide metabolism in relation to purine enzyme activities in rat liver, human erythrocytes and cultured human skin fibroblasts, rapid and sensitive assays for the purine enzymes, adenosine deaminase (EC 2.5.4.4), adenosine kinase (EC 2.7.1.20), hyposanthine phosphoribosyltransferase (EC 2.4.28), adenine phosphoribosyltransferase (EC 2.4.2.7) and 5'-nucleotidase (EC 3.1.3.5) were standardized for these tissues. Adenosine deaminase was assayed by measuring the formation of product, inosine (plus traces of hypoxanthine), isolated chromatographically with 95% recovery of inosine. The other enzymes were assayed by isolating the labelled product or substrate nucleotides as lanthanum salts. Fibroblast enzymes were assayed using thin-layer chromatographic procedures because the high levels of 5'-nucleotidase present in this tissue interferred with the formation of LaCl3 salts. The lanthanum and the thin-layer chromatographic methods agreed within 10%. Liver cell sap had the highest activities of all purine enzymes except for 5'-nucleotidase and adenosine deaminase which were highest in fibroblasts. Erythrocytes had lowest activities of all except for hypoxanthine phosphoribosyltransferase which was intermediate between the liver and fibroblasts. Erhthrocytes were devoid of 5'-nucleotidase activity. Hepatic adenosine kinase activity was thought to control the rate of loss of adenine nucleotides in the tissue. Erythrocytes had excellent purine salvage capacity, but due to the relatively low activity of adenosine deaminase, deamination might be rate limiting in the formation of guanine nucleotides. Fibroblasts, with high levels of 5'-nucleotidase, have the potential to catabolize adenine nucleotides beyond the control od adenosine kinase. The purine salvage capacity in the three tissues was erythrocyte greater than liver greater than fibroblasts. Based on purine enzyme activities, erythrocytes offer a unique system to study adenine salvage; fibroblasts to study adenine degradation; and liver to study both salvage and degradation.
...
PMID:Adenine nucleotide metabolism in relation to purine enzymes in liver, erythrocytes and cultured fibroblasts. 118 98


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

---