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PubMedDate not supplied

Allosteric regulation of beef liver arginase activity by L-ornithine.

Inhibition of beef liver arginase by L-ornithine was investigated with two sets of independent experiments. Progress curves of the production of urea were simulated with two integrated Michaelis-Menten equations for competitive and non-competitive inhibition by ornithine. Both fitted the curves well, but failed to correctly predict the inhibition when the reaction was started with ornithine already present. Measurement of initial rates of reaction enabled an allosteric model to be built in accordance to Monod-Wyman-Changeux: arginine preferentially binds to the active state R and ornithine preferentially binds to the inactive state T. In the absence of both ligands, the R in equilibrium T equilibrium slightly favours the active state and both states bind ornithine more strongly than arginine. No great variation was observed in the 6 parameters of the model by assuming the enzyme to be a trimer or a tetramer. The model was able to predict not only the initial rate curves, from which it was derived, but also the progress curves independently obtained.

Allosteric Regulation↗
PubMed1983

Evidence for a lymphokine enhancing arginase activity during allograft rejection.

The production of urea and ornithine is increased greatly in spleen cell cultures of an allograft recipient in the presence of donor cells (secondary MLC) in comparison to that of primary MLC (without previous allograft). This phenomenon appears after 24 hr of culture and reaches its maximum at 48 hr. The greatest increase in urea production is observed when the recipient spleen cells are collected at the time of allograft rejection. To obtain this extra production of urea, the stimulating cells in MLC should specifically be of the donor type or at least bear one homology with donor cells at the K or D locus. The increased production of urea and ornithine during MLC results from the action of a lymphokine released by recipient cells in the presence of donor cells. This factor acts upon cells present in bone marrow, spleen, and elicited peritoneal cells but is absent or is present in smaller quantities in thymus and lymph node cells. Target cells of this factor possess numerous macrophage features and could be immature cells of the macrophage line. The lymphokine responsible for this phenomenon is heat-stable, destroyed by trypsin, chymotrypsin, and neuraminidase, and has a m.w. around 32,000. It acts upon its target cells by increasing arginase activity, which results in the production of a large amount of ornithine, an important precursor of polyamine biosynthesis.

Amino Acids↗
PubMed1980

Purification and some properties of human heart arginase.

Arginase from extracts of human heart was purified about 1500-fold. In polyacrylamide-gel electrophoresis the enzyme migrated to the cathode at pH 5.5, showing very low mobility at pH 8.9. Molecular weight determined by gel filtration was 120 000. The Km for L-arginine was 5 mM. L-Ornithine and L-lysine were competitive inhibitors. The enzyme was completely inactivated by treatment with EDTA, and dissociated into subunits with mol.wt. of about 30 000. Addition of Mn2+ ions to the inactive subunits resulted in reappearance of the enzyme activity; the molecular weight of the reactivated enzyme corresponded to that of the native form.

Amino Acids↗
PubMed1981

Immobilization of arginase on hollow fiber hemodialyzer.

The enzyme arginase, purified from bovine liver, was covalently immobilized by the glutaraldehyde method to the inner surface of Cuprophan hollow fibers of a conventional hemodialyzer with a surface 1.3 m3. The yield of the process was 0.3 microgram/cm2 of active enzyme at physiological pH. The immobilization method did not adversely affect the physical and mechanical properties of hollow fibers neither their hemocompatibility. After sterilization with ethylene oxide, the bioreactor was able to metabolize five liters of 50 microM arginine solution at pH 7.4, in six hours.

Arginase↗
PubMed1980

[The influence of fasting and cortisol upon arginosuccinate synthetase, arginosuccinase and arginase levels in guinea pig liver (author's transl)].

The influence of fasting and cortisol treatment on the levels of arginosuccinate synthetase (E.C. 6.3.4.5.), ARGINOSUCCINASe (E.C. 4.3.2.1) and arginase (C.E. 3.5.3.1) from guinea pig liver has been investigated. The results show a general increase in the levels of the mentioned enzymes, with specific enzyme synthesis for fasting, and unspecific for cortisol treatment.

Animals↗
PubMed1976

[Inhibitory effect of ellipticine (dimethyl-5,11-(6H) pyrido (4,3-b) carbazole on the induction of liver cancer by BT6 (N,N-dimethyl-p-(benzothiazolylazo) analine) and its effect on the levels of cytochrome P450 and arginase activity].

Under the conditions of our tests, ellipticine inhibits remarkably the carcinogenic action of BT6 on the liver, characterized, in particular, by the swiftness of its outbreak. Under the influence of this carcinostatic compound, a considerable activation of liver metabolism is observed, resulting in an hyperproduction of cytochrome P450, while the arginase capital is restored after an appreciable fall, as if ellipticine played a favourable part in the safeguard of this enzyme, recognized as one of the targets of liver carcinogens. The relationships between various effects of ellipticine are discussed.

Alkaloids↗
PubMed1996

Evidence for sltA1 as a salt-sensitive allele of the arginase gene (agaA) in the ascomycete Aspergillus nidulans.

Strains of Aspergillus nidulans carrying the sltA1 mutation, conferring sensitivity to KCl and NaCl, also showed an arginine-sensitive phenotype whereby concentrations of the L-amino acid at or above 10 mM were toxic to growth. Sexual progeny of a cross between a sltA1 mutant and a wild-type strain showed a co-segregation of salt and arginine sensitivity. Similarly, revertants to salt tolerance showed a loss of arginine sensitivity as did sltA1 strains that were transformed with a cosmid carrying the putative sltA1+ wild-type allele. In addition, arginine sensitivity could be relieved by L-ornithine. It is suggested that sltA1 is a salt-sensitive allele of the arginase gene (agaA).

Alleles↗
PubMed1998

Porcine somatotropin, dietary protein and energy effects on arginase and transaminase activities in pigs.

Two experiments were conducted with cross-bred barrows to determine the effect of somatotropin administration on liver enzyme activities. In the first experiment, pigs growing from 26 to 55 kg body weight were given two doses of pituitary porcine somatotropin (pST; 0 and 100 micrograms per kg body weight) and three levels of dietary energy (60, 80 and 100% of free choice intake). In the second experiment, pigs growing from 30 to 60 kg body weight were given two doses of recombinant porcine somatotropin (rpST; 0 and 100 micrograms per kg body weight) and five levels of dietary crude protein (110, 150, 190, 230 and 270 g crude protein/kg diet). Liver arginase (ARG, EC 3.5.3.1) and aspartate aminotransferase (AAT, EC 2.6.1.1) activities were then determined in organ samples taken at slaughter time. Dietary energy did not change liver ARG. Activities of both ARG and AAT increased as dietary crude protein increased. Both pST and rpST decreased ARG, AAT and serum utrea nitrogen. There was a lack of interaction between rpST therapy and dietary protein on either ARG or AAT activities, suggesting that set nutritional states are not required for expression of pST effects.

Animal Nutritional Physiological Phenomena↗
PubMed1975

Unsuccessful trial of gene replacement in arginase deficiency.

The Shope virus following cutaneous inoculation produces skin papillomas in rabbits and induces a virus-coded arginase in the squameous epithelium of these papillomas. The only discernible effect of the virus inoculated intravenously in rabbits and other animals was a decrease of the serum arginine concentration. Intravenous injection in 3 hyperargininemic patients, however, did not influence the underlying metabolic disease.

Amino Acid Metabolism, Inborn Errors↗
PubMed1982

Treatment of hyperargininaemia due to arginase deficiency with a chemically defined diet.

A brother and sister aged 11 and 17 years have been reported previously to have hyperargininaemia and arginase deficiency: they were treated with a semi-synthetic diet consisting of fat, carbohydrate, minerals, vitamins and essential amino acids in amounts equivalent to 0.55-0.65 g protein kg-1 day-1 for 2 years. Plasma arginine levels fell from 0.50-0.90 mumol/1 to 0.13-0.30 mumol/1 (normal range 0.02-0.15). Increased concentrations of arginine in the cerebrospinal fluid (CSF) fell from 0.069-0.098 mumol/l to 0.040-0.056 mumol/l (normal mean +/- SD = 0.020 +/- 0.006). Dibasic aminoaciduria returned to normal within 1 week. Substitution of the keto-acid analogues of five essential amino acids in the formula lowered arginine concentrations further, but proved to be unpalatable. Urinary concentrations of orotic acid, uridine and uracil fell toward normal but remained increased, even when the plasma ammonia concentration was measured as normal. Both patients showed a stable clinical improvement.

Adolescent↗
PubMed1978

Enzymes of Krebs-Henseleit Cycle in Vitis vinifera L: III. In Vivo and In Vitro Studies of Arginase.

The presence of arginase (EC 3.5.3.7) in various tissues from Vitis vinifera L. cultivars was demonstrated by both in vivo and in vitro enzyme assays. Initial velocities determined by the two methods were in close agreement. Optimum conditions for maximum enzyme activity were 25 to 30 millimolar l-arginine, about 1 millimolar Mn(2+) (pH 9.4 to 9.8), and incubation temperature of 37 to 38 C. l-Arginine hydrolysis was linear with increasing sliced fresh tissue up to 500 milligrams for in vivo assay, and with enzyme extract equivalent up to about 200 milligrams of fresh tissue for in vitro. Similarly, l-arginine hydrolysis was linear with incubation time for the first 45 minutes for in vivo assay and for the first 20 minutes for in vitro.

Journal Article↗
PubMed1983

Endogenous Inactivators of Arginase, l-Arginine Decarboxylase, and Agmatine Amidinohydrolase in Evernia prunastri Thallus.

Arginase (EC 3.5.3.1), l-arginine decarboxylase (EC 4.1.1.19), and agmatine amidinohydrolase (EC 3.5.3.11) activities spontaneously decay in Evernia prunastri thalli incubated on 40 millimolar l-arginine used as inducer of the three enzymes if dithiothreitol is not added to the media. Lichen thalli accumulate both chloroatranorin and evernic acid in parallel to the loss of activity. These substances behave as inactivators of the enzymes at a range of concentrations between 2 and 20 micromolar, whereas several concentrations of dithiothreitol reverse, to some extent, the in vitro inactivation.

Journal Article↗
PubMed1990

Purification and Properties of Arginase from Soybean, Glycine max, Axes.

Arginase (EC 3.5.3.1) was purified to homogeneity from cytosol of soybean, Glycine max, axes by chromatographic separations on Sephadex G-200, DEAE-sephacel, hydroxyapatite, and arginine-affinity columns. The molecular weight of the enzyme estimated by pore gradient gel electrophoresis was 240,000, while sodium dodecyl sulfate polyacrylamide gel electrophoresis gave a single band at the molecular weight of 60,000. The optimal pH for activity was 9.5 and the K(m) value was 83 millimolar. The enzyme was stimulated by polyamines such as putrescine.

Journal Article↗
PubMed1995

Crystallization and preliminary X-ray diffraction studies of arginase from a thermophilic organism Bacillus caldevelox.

A thermostable hexameric arginase purified from the extreme thermophile Bacillus caldevelox has been crystallized from Hepes buffer at pH 7.5 in the presence of 12% polyethylene glycol 4000 and 10% 2-propanol, and from cacodylate buffer at pH 7.2 in the presence of 15% 2-propanol and sodium citrate. The latter crystals are more suitable for X-ray diffraction analysis. The crystals are in the orthorhombic space group P2(1)2(1)2(1) with unit-cell dimensions a = 156.3, b = 148.0 and c = 85.4 A. The asymmetric unit contains one hexamer (approximate molecular mass 183 kDa) and has a solvent content of approximately 54%. The crystals diffract to 2.8 A resolution.

Journal Article↗
PubMed1984

Polyamine starvation prolongs the S and G2 phases of polyamine-dependent (arginase-deficient) CHO cells.

This study analyzes the effects of polyamine starvation on cell cycle traverse of an arginase-deficient CHO cell variant (CHO-A7). These cells grow well in serum-free medium, provided that it contains ornithine or polyamines or both. In the absence of ornithine or polyamines or both, the CHO-A7 cells develop severe polyamine deficiency and, as a consequence, grow more slowly. When grown to a stationary phase in the presence of ornithine or putrescine or both, the CHO-A7 cells became arrested in G0/early G1. However, when starved for ornithine and polyamines, they accumulated in the S and G2 phases. Ornithine and polyamine starvation of CHO-A7 cells causes an increase in ornithine decarboxylase activity. When this increase was prevented by treatment with DL-alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase, growth was further suppressed, and a greater fraction of cells were found in the S and G2 phases of the cell cycle.

Animals↗
PubMed1988

Effect of diet on transaminase and arginase activities.

The composition of the diet greatly influences the enzyme activities of the liver. The effect of low carbohydrate diet on AST, ALT and arginase activities in liver and serum of rats was determined in the present study. Liver ALT and serum AST were significantly increased in animals fed on low carbohydrate diet, the activities of other enzymes remained unchanged.

Journal Article↗