Two different hepatic adenosine deaminases in the chicken

Inheritance of adenosine deaminase variants in chickens and turkeys

Blood cell lysates of chickens and turkeys were subjected to starch gel electrophoresis and the gels were stained for adenosine deaminase. Two zones were observed singly or together in the electrophoretic patterns of each lysate. Zones of chicken lysates were analogous in electrophoretic mobility to those of turkeys. An extra zone which appeared in patterns of a sample stored over one month was not detected in patterns of a second aliquot of stored sample treated with a reducing agent prior to electrophoresis. Family data involving 110 chicken progeny and 221 turkey progeny supported the hypothesis that these zones were controlled by two codominant alleles designated ADAA and ADAB. In the two Leghorn strains studied ADAB was much more frequent than ADAA, but the frequency distribution was reversed in the Small White turkey strain examined.

Adenosine deaminase 2 from chicken liver: purification, characterization, and N-terminal amino acid sequence

Adenosine deaminase (ADA) is involved in purine metabolism and plays an important role in the mechanism of the immune system. ADA activity is composed of two kinetically distinct isozymes, which are referred to as ADA1 and ADA2. ADA1 is widely distributed in many animals and well characterized. On the contrary, relatively little is known about ADA2. In this study, we first purified ADA2 to homogeneity from chicken liver. The purified enzyme had a molecular mass of approximately 110 kDa on gel filtration. Also, the enzyme was shown to be a homodimer with an estimated molecular mass of 61 kDa on SDS-PAGE. Following treatment with N-glycosidase, the molecular mass of ADA2 changed to 55 kDa. Several properties of the highly purified ADA2 were also investigated in this study. Furthermore, the N-terminal amino acid sequence of ADA2 was determined.

Adenosine deaminase: functional implications and different classes of inhibitors

Adenosine deaminase (ADA) is an enzyme of the purine metabolism which catalyzes the irreversible deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. This ubiquitous enzyme has been found in a wide variety of microorganisms, plants, and invertebrates. In addition, it is present in all mammalian cells that play a central role in the differentiation and maturation of the lymphoid system. However, despite a number of studies performed to date, the physiological role played by ADA in the different tissues is not clear. Inherited ADA deficiency causes severe combined immunodeficiency disease (ADA-SCID), in which both B-cell and T-cell development is impaired. ADA-SCID has been the first disorder to be treated by gene therapy, using polyethylene glycol-modified bovine ADA (PEG-ADA). Conversely, there are several diseases in which the level of ADA is above normal. A number of ADA inhibitors have been designed and synthesized, classified as ground-state and transition-state inhibitors. They may be used to mimic the genetic deficiency of the enzyme, in lymphoproliferative disorders or immunosuppressive therapy (i.e., in graft rejection), to potentiate the effect of antileukemic or antiviral nucleosides, and, together with adenosine kinase, to reduce breakdown of adenosine in inflammation, hypertension, and ischemic injury.

Adenosine deaminase in the adductor muscle of the scallop, Patinopecten yessoensis

1. The scallop enzyme was separated by DE52 ion-exchange chromatography into two forms with the same mol. wt of 38,000 and similar characteristics. 2. The enzyme was inactivated in the absence of dithiothreitol and complete reactivation was achieved by adding the agent within a critical storage period. 3. The apparent values of pKm and Vmax sensitively increased as ionic strength was raised to 250 mM and phosphate and sodium ions elevated the former value with a further increase of the ionic strength. 4. The apparent activation energies for the alpha (Vmax/Km) and beta (Vmax) parameters of both the forms were approximately 5 and 8 kcal/mol, respectively. 5. The enzyme deaminated 2'-, 3'-deoxyadenosine and 2',3'-isopropylidene adenosine but did not deaminate 5'-deoxyadenosine, alpha-adenosine and adenine nucleotides. 6. The affinity for inosine was much lowered with a high Ki value. Adenine and purine riboside inhibited the enzyme completely, and coformycin was a tight, slow binding inhibitor.

Purification of adenosine deaminase from chicken-egg yolk by affinity column chromatography

Adenosine deaminase (adenosine aminohydrolase; E.C. 3.5.4.4) has been purified 4686-fold from egg yolk. The procedure developed was used to isolate the enzyme from eight chicken eggs. An easily prepared affinity column employing purine riboside was used as the final step in the purification. The method developed permits the rapid isolation and a high recovery of the protein. The specific activity of the enzyme preparation obtained is 81.4 mU/mg.

Adenosine deaminase activity of chicken erythrocyte and heart cytosols

1. The adenosine deaminase (ADA) activities of chicken erythrocyte and heart cytosols had pH optima of 6.5. The temperature optima for erythrocyte and heart ADA were 30 and 35 degrees C, respectively. 2. The deoxyadenosine/adenosine deamination ratios ranged from 0.75 to 0.84 for both ADA activities. 3. For erythrocyte ADA, Km values were 8.9-12.9 microM adenosine (range) and 8.3 microM 2'-deoxyadenosine. For heart ADA, Km values were 6.7-12.0 microM adenosine (range) and 5.3 microM 2'-deoxyadenosine. 4. Inosine was a competitive inhibitor of both erythrocyte (Ki = 73 microM) and heart (Ki = 109 microM) ADA.

Purification and partial characterization of brain adenosine deaminase: inhibition by purine compounds and by drugs

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.

Separation of human from mouse and monkey adenosine deaminase by ion-exchange chromatography following retroviral-mediated gene transfer

A method for the chromatographic separation of human adenosine deaminase (ADA) from murine and monkey ADA is described. This procedure was developed in order to detect the expression of low or moderate levels of human ADA following retroviral-mediated gene transfer of cloned human ADA gene sequences into both mouse and monkey cells. Protein separation was achieved on a Mono Q (HR 5/5) anion-exchange column using the Pharmacia fast protein liquid chromatography system and was found to be a highly reproducible method yielding enzymatically active protein. An increasing linear gradient extending from 0.05 to 0.5 M potassium chloride (pH 7.5) was used to elute the enzyme. Under these conditions, most human ADA does not bind to the column and elutes in the low-salt buffer (0.05 M KCl), while murine ADA elutes at 0.12 M KCl and monkey ADA at 0.15 M KCl. The column fractions were assayed for ADA activity, and the characteristic isozyme banding patterns for human, mouse, and monkey ADA were confirmed by starch gel electrophoresis. This procedure allows the rapid and reproducible separation of human ADA from that of other species and yields partially purified enzymatically active protein.

Distribution of adenosine deaminase in some rat tissues. Inhibition by ethanol and dimethyl sulfoxide

The level of adenosine deaminase in various rat tissues has been tested. The enzyme activity of cytosolic fractions decreased in the following order: lung greater than spleen greater than small intestine greater than stomach greater than kidney greater than heart greater than liver greater than skeletal muscle greater than forebrain greater than cerebellum. The enzyme had identical patterns from tissue to tissue with respect to Km, V, and Ki values for ethanol and for dimethyl sulfoxide, with respect to electrophoretic behaviour and to inhibition by antibodies anti-rat brain adenosine deaminase.

Adenosine deaminase (ADA) in leukemia: clinical value of plasma ADA activity and characterization of leukemic cell ADA

Adenosine deaminase (ADA) activity was measured in plasma, erythrocytes, and mononuclear cells from 18 patients with acute and chronic leukemia. High levels of ADA activities were found in plasma, erythrocytes, and mononuclear cells from patients with acute leukemia, especially acute lymphoblastic leukemia, and blastic crisis of chronic myeloid leukemia. Serial determination of plasma ADA activities was done in 9 patients with acute leukemia. All patients untreated or in relapse had an elevation of plasma ADA activity, which decreased to normal or subnormal levels during complete remission. On starch gel electrophoresis, plasma ADA in leukemic patients separated into two bands. The major band showed a mobility identical to that of normal red cells and mononuclear cells, and the minor band corresponded to that of normal plasma ADA. Enzymatic and immunological studies were performed on ADA from leukemic cells of acute myeloid and lymphoblastic leukemia. There were no differences in Michaelis constant for adenosine, thermostability, electrophoretic mobility, immunological reactivity, and specific activity between ADA of leukemic cells and normal mononuclear cells. These results strongly suggest that the increased ADA activity in leukemic cells is caused by an increased synthesis of a structurally normal enzyme and that increased plasma ADA activity in leukemic patients reflects an increment of leukemic cells in bone marrow. Therefore, serial determination of plasma ADA activities seems to provide a good indicator of the total mass of leukemic cells in bone marrow.

Characterization of adenosine deaminase from normal human epidermis and squamous cell carcinoma of the skin

We compared the characteristics of adenosine deaminases (ADs) (E.C. 3.5.4.4.) in squamous cell carcinoma and normal human epidermis. Increased specific activity (per mg protein) of AD was observed in squamous cell carcinoma compared with that of the normal epidermis. In normal human epidermis most of the AD existed as a large form (Mr 300,000-350,000, type A). Squamous cell carcinoma of the skin was characterized by a high proportion of small-form (Mr 30,000-40,000, type C) AD. The proportion of the small-form enzyme varied from tumor to tumor. Comparison of the large-form AD from squamous cell carcinoma to that from normal epidermis revealed that both enzymes were similar in relative substrate specificity, Km values for adenosine, pH optima, heat stability pattern, isoelectric point, and sensitivity to inhibition by coformycin, a tight binding inhibitor of AD. However, the low molecular weight of AD from squamous cell carcinoma was less heat stable than that from the large-molecular-weight form. Increased AD activity and the high proportion of the small form of AD might be significant features of squamous cell carcinoma of the skin.

Simultaneous decrease in deamination of 5'-adenylic acid and 5'-deoxy-5'-S-isobutylthioadenosine in chick-embryo fibroblasts infected by Rous sarcoma virus

The rate of deamination of 5'-deoxy-5'-S-isobutylthioadenosine [(iBuS5'Ado] in chick embryo fibroblasts was substantially reduced after their infection and morphological transformation by Rous sarcoma virus. Concomitant with the reduction in rate of (iBuS)5'Ado deamination there was a decrease in adenosine deaminase and 5'-adenylic acid deaminase activities. The drop of these activities was related to infection and not to the expression of the src gene. (iBuS)5'Ado was deaminated by at least three enzymes or isoenzymes whose apparent molecular weights have been estimated to be 295000, 121000 and 37000 respectively. Two of these enzymes have been characterized as 5'-adenylic acid deaminase and the heavy form of adenosine deaminase, respectively.

Purification and properties of the adenosine deaminase from the midgut gland of a marine bivalved mollusc, Atrina spp

1. The adenosine deaminase has an approximate molecular weight of 130,000-140,000 and the composition of two polypeptide units (mol. wt about 68,000) is suggested, by means of SDS disc electrophoresis. 2. Both the alpha (Vm/Km) and beta (Vm) parameters were varied with pH and temperature. RSS (relative substrate specificity) adenosine and deoxyadenosine values for alpha and beta were 1.2 and 1.1, respectively. 3. Adenine, 2'-, 3', 5'-AMP, 5'-deoxyAMP, ADP and ATP were not deaminated by the enzyme. 4. Inhibition by Mg2+ was found in reaction with adenosine at pH 8 but not with deoxyadenosine at the same pH. Mn2+, which did not affect the reaction rate at pH 4 and 5, showed competitive inhibitory effects at pH 6, 7 and 8.

Purification of multiple forms of adenosine deaminase from rabbit intestine

Two forms of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4), differing in molecular size, have been purified and obtained in homogeneous form from rabbit intestine. The purification procedures involved extraction with acetate buffer, pH 5.5, precipitation and fractional reextraction with (NH4)2SO4, ion-exchange chromatography on DEAE-cellulose and gel filtration on Sephadex G-75 and Sephadex G-200. Gel filtrations analysis gave molecular weight estimates of 265 000 and 32 000 for the large and small deaminases respectively. The two enzymes forms had similar pH optima and pH stability ranges.

Adenosine deaminase in chicken-egg yolk and its relation to homologous enzymes in liver and plasma of the adult hen

Chicken egg yolk contains an adenosine deaminase that was investigated after purifying about 500 times. It has a pH optimum at 6.5, aKm of 6.6 times 10(-5) mol/l and an approximate molecular weight of 14000; higher molecular forms could not be detected. It was compared with the adenosine deaminases of chicken liver and blood plasma. From this comparison it is evident that this protein has undergone certain changes during the successive events leading to its final structure (secretion by the liver, transport through blood plasma to the oocytes and development of the egg): a common subunit with an approximate molecular weight of 15000 may be the basis of the physiological diversifications. Substrate specificity of the purified extracts extends to cytidine and guanosine also, although certain observations point to different enzymes being involved. Deoxyadenosine is also deaminated. Cu2+, Zn2+, and Pb2+ are inhibiting and free -SH seems essential for activity.