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PubMed1979

Chemical modification of rat liver arginase.

Chemical modifications were used to search for catalytically important residues of rat liver arginase. The results of carbamoylation, nitration and diazotization suggest that lysyl and tyrosyl residues are not involved in the catalytic function of arginase. The modification of 5--6 tryptophanyl residues by N-bromosuccinimide or 2-hydroxy-5-nitrobenzyl bromide led to about 90% inhibition of the enzyme activity. Photooxidation of 21 histydyl residues also led to considerable inactivation of arginase. The modification of tryptophanyl and histidyl residues did not cause dissociation of the enzyme into subunits.

Amino Acids↗
PubMedDate not supplied

[Effect of alcohol intoxication on activity of enzymes in ethanol oxidation and on arginase activity in rat liver].

In chronic alcohol intoxication activity of alcohol-oxidizing systems in liver tissue was not distinctly altered as shown by estimation of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (AcDH) activities, whereas the arginase activity was increased 1.5-2-fold. At the same time, the activities ADH, AcDH and arginase tended to decrease in acute alcohol intoxication of slight and middle degree. These alterations in the enzymatic activity were more pronounced in acute intoxication occurring simultaneously with chronic alcoholization. Lethal doses of alcohol caused a decrease in ADH and AcDH activities but did not affect the arginase activity.

Alcohol Dehydrogenase↗
PubMed1983

Identification of the apparently lymphocyte-specific human liver-derived inhibitory protein (LIP) as cytoplasmic liver L-arginase.

This paper describes the identification of a human liver-derived inhibitory protein (LIP), which has recently been purified, as cytoplasmic liver arginase. Arginase activity was purified to homogeneity parallel to lymphocyte proliferation inhibitory activity. The reaction products were identified by thin-layer chromatography to be ornithine and urea from arginine. The enzyme activity could be increased by the addition of manganese ions, and the inhibitory effect on cell proliferation could be reversed by additional arginine. An antiserum against LIP cross-reacted with cytoplasmic calf liver arginase.

Animals↗
PubMed1984

[Urea and arginase activity in rat liver during the administration of thioacetamide].

The authors measure the concentration of urea and arginase activity at pH 6.5 and 9.7 in the rat liver at intervals during the administration thioacetamide (TAM) at a dose of 50 mg per kg of body weight and per day. The values obtained correlate the amount of urea and the arginase activity at pH 6.5 and 9.7 during TAM administration for the intervals comprised between 1-12 days and 12-30 days. These results suggest that the concentration of liver urea depends mainly of the level at arginase activity, which is regulated by the proton concentration of the internal environment.

Acetamides↗
PubMed1978

Direct colorimetric determination of serum arginase in various domestic animals.

A direct colorimetric method for the determination of serum arginase activity in various domestic animals is described. Serum arginase activity in healthy mature dogs, cats, horses, cattle, sheep, and pigs ranged from 0 to 14 IU/L. Serum arginase activity increased considerably in these animals during experimental hepatic damage induced by oral administration of carbon tetrachloride.

Animals↗
PubMedDate not supplied

[Activity of arginase and proteolytic processes in the brain and liver of rats in cold acclimatization].

The activity of arginase, neutral peptidohydrolase (protaminase) and total intensity of autolysis were determined in the brain and liver of rats on the 1st, 3d, 30th and 45th days animal stay at a temperature of 2-4 degrees C. in the process of rats acclimatization to cold there occurs a correlation in the brain - between the activity of arginase and neutral peptidohydrolase, in the liver - between the arginase activity and total proteolytical activity (autolysis).

Acclimatization↗
PubMed1982

[Multiple forms of rat liver arginase].

Two differently charged isoforms of arginase were isolated from rat liver and partially purified. The isoelectric point for isoform I possessing more than 90% of the total arginase activity lies around 9.3, while that for isoform II lies around pH 7.0. Both isoforms have similar molecular weights (120,000) and close Km values (1-3 mM). In order to stabilize the enzyme activity both isoforms were obtained in an immobilized state. Study of the effects of some cholate compounds, SH-reagents and inhibitors on soluble and immobilized isoforms revealed some differences in the properties of these isoforms. Isoform II subunits are more tightly bound to Mn2+ than those of isoform I; the role of SH-groups in manifestation of the catalytic activity of the isoforms appears to be different. Isoform I possessing a positive charge (this is in agreement with the literary data) can be related to ureothelic enzymes, while isoform II is close to non-ureothelic arginases from brain and kidney not coupled with the ammonium detoxication mechanism.

Animals↗
PubMed1981

[Arginase characteristics in an ammoniotele].

Arginase (EC 3.5.3.1.) is active in the hepatopancreas, gills and pincer muscle of the ammoniotele Carcinus maenas. Its activity in the hepatopancreas is mainly localized in mitochondria. The enzyme becomes inactive at 37 degrees C if the assay is carried out without previous incubation with Mn2+; the optimum temperature for the fully activated enzyme is 47 degrees C. Two fractions showing arginase activity can be separated on DEAE-cellulose at pH 8.3, the most active being eluted by a linear gradient of KCl at a concentration of 0.3 divided by 0.4M, the other with a buffer front. Since ornithine transaminase (EC 2.6.1.13.) activity has been detected in the hepatopancreas, arginase activity in this organ is possibly related to ornithine catabolism leading to proline and glutamate.

Animals↗
PubMed1980

Fluorometric micromethod for determination of arginase activity in dried blood spots on filter paper.

We describe a microfluorometric method for determination of arginase activity in dried blood spots on filter paper. The arginase in discs punched from such dried blood specimens is activated by preincubation with Mn2+ at 37 degrees C. After incubation with substrate at the same temperature, urea is determined fluorometrically by oxidation of NADH to NAD+ in a coupled kinetic reaction. We compare the results of this method with those of a colorimetric method involving liquid blood samples, and assess the stability of the enzyme in dried blood on filter paper. The presence of serum has no effect on the activity. This method may be useful in the early detection of arginase deficiency and certain hematological disorders.

Adult↗
PubMedDate not supplied

Effect of hydrocortisone on arginase activity in ICRC mouse mammary tumours in vitro.

Three fold increase of arginase activity was observed in hydrocortisone treated mammary tumour tissue when compared to the untreated tissue in vitro. No change in succinic dehydrogenase activity was observed. It is likely that arginase present in mammary tumour is due to the presence of mammary tumour virus and it is tempting to speculate that the increase in arginase activity by hydrocortisone may be due to sustained viral production in the presence of hydrocortisone.

Animals↗
PubMed1986

A new case of arginase deficiency in a Spanish male.

A new case of arginase deficiency is reported in a male newborn from Spain. In contrast with the majority of the earlier cases, this infant showed severe protein intolerance of early onset. The diagnosis was based on the assay of the urea cycle enzymes in a postmortem liver sample. Levels of erythrocyte arginase were also determined in the parents and in a sister of the patient, and were consistent with heterozygosity. From a study of the pedigree it appears that arginase deficiency in this family presents a dramatic course.

Amino Acid Metabolism, Inborn Errors↗
PubMed2006

A patient with arginase deficiency and episodic hyperammonemia successfully treated with menses cessation.

Arginase deficiency is an urea cycle disorder that generally presents with mental retardation and spasticity, yet uncommonly with episodes of hyperammonemia. A female adolescent with arginase deficiency developed hyperammonemic episodes temporally related to her menstrual cycle, which ceased upon adequate treatment with depot medroxy progesterone acetate. A similar case was previously reported. A catamenial trigger should be considered in adolescent female arginase-deficient patients with episodes of hyperammonemia.

Adult↗
PubMed1997

Amino Acid Utilization in Seeds of Loblolly Pine during Germination and Early Seedling Growth (I. Arginine and Arginase Activity).

The mobilization and utilization of the major storage proteins in loblolly pine (Pinus taeda L.) seeds following imbibition were investigated. Most of the seed protein reserves were contained within the megagametophyte. Breakdown of these proteins occurred primarily following radicle emergence and correlated with a substantial increase in the free amino acid pool in the seedling; the majority of this increase appeared to be the result of export from the megagametophyte. The megagametophyte was able to break down storage proteins and export free amino acids in the absence of the seedling. Arginine (Arg) was the most abundant amino acid among the principal storage proteins of the megagametophyte and was a major component of the free amino acid pools in both the seedling and the megagametophyte. The increase in free Arg coincided with a marked increase in arginase activity, mainly localized within the cotyledons and epicotyl of the seedling. Arginase activity was negligible in isolated seedlings. Experiments with phenylphosphorodiamidate, a urease inhibitor, supported the hypothesis that arginase participates in Arg metabolism in the seedling. The results of this study indicate that Arg could play an important role in the nutrition of loblolly pine during early seedling growth.

Journal Article↗
PubMed1987

[Arginase deficiency, congenital hypothyroidism and hepatic fibrosis].

A new case of arginase deficiency in a newborn is reported. In contrast with previous cases, this infant showed severe protein intolerance of early onset. Diagnosis was based on the assay of urea cycle enzymes in a postmortem liver sample and on arginase activity in erythrocytes of parents and sister of the patient. "Pedigree" shows that arginase deficiency in this family presents a dramatic course. Congenital hypothyroidism with athyreosis, moderate hepatic fibrosis and megamitochondria are present in the same subject. Possible significance of these findings is briefly discussed.

Congenital Hypothyroidism↗
PubMed1977

A simple screening test for arginase deficiency (hyperargininemia).

A simple fluorescent spot screening test has been developed for the identification of individuals with arginase deficiency (hyperargininemia). The assay is based on the coversion of arginine to ornithine and urea by arginase present in 1/8 inch disc of dried blood on filter paper. The enzyme activity is visually estimated by the oxidation of NAD-H to NAD+ in a coupled kinetic reaction. In the absence of the enzyme, there is no oxidation of the NAD-H and consequently no loss of fluorescence. The screening assay has been used to identify successfully both heterozygous and homozygous arginase-deficient crabeater macaques (M. fascicularis) as well as three patients with hyperargininemia. This test can be used to screen large numbers of patients with mental retardation or seizure disorders rapidly to determine the frequency of this disorder more precisely.

Animals↗
PubMed1999

Identification of a novel R21X mutation in the liver-type arginase gene (ARG1) in four Portuguese patients with argininemia.

Argininemia is a rare autossomal recessive disorder caused by deficiency in the cytosolic liver-type arginase enzyme (L-arginine urea-hydrolase; E.C. 3.5.3.1). In order to investigate the molecular basis for argininemia in four unrelated Portuguese patients (two from northern Portugal and two from Madeira Island) we performed a DNA sequence analysis of all the exons and exon/intron boundaries of the liver-type arginase gene (ARG1). All patients were found to be homozygous for a newly identified C ->T transition in codon 21 (exon 2) substituting arginine for a premature stop codon (R21X: CGA to TGA) and generating a NlaIII restriction site. Restriction digestion following PCR amplification of ARG1 exon 2 confirmed the presence of the mutation.

Amino Acid Metabolism, Inborn Errors↗
PubMed1983

Demonstration of a concanavalin A-induced lymphokine enhancing arginase activity. Effect of presensitization by a skin allograft.

In response to concanavalin A (Con A) mouse spleen cells produce increased amounts of urea. This increase results from arginase activity degrading arginine into urea and ornithine. It is mediated by a soluble protein factor, characterized by its heat stability (10 min at 80 degrees C) and a molecular weight of approximately 32 000. The factor is produced by T cells and acts on a cell population mainly present in bone marrow and spleen. Splenocytes collected from skin allograft recipients during rejection produce more urea in response to Con A than those obtained from normal or syngeneically grafted mice. The maximum urea increase is observed just before and maintained during rejection, declining rapidly thereafter. This phenomenon is explained (a) by a 10-15-fold increase in arginase-enhancing factor production by Con A-stimulated allograft recipient spleen cells and (b) by an increased responsiveness of these splenocytes to the lymphokine.

Animals↗