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

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Query: EC:6.3.5.5 (CPS)
1,262 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methods are described for the determination of the activity of urea cycle enzymes in human and rat tissues by chromatography and videodensitometry(CV-technique). With specific substrates carbamoyl-phosphate synthetase and ornithine carbamoyltransferase activities were determined as the amounts of citrulline formed. Argininosuccinate synthetase, argininosuccinate lyase and arginase activities were measured from the changes in ornithine concentration. For measuring the activity of five enzymes 5 to 10 mg wet weight of tissue was sufficient. The CV-technique could be conveniently applied for the investigation of enzyme content in samples from human biopsy.
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PMID:Determination of enzyme activity by chromatography and videodensitometry. II. Urea cycle enzymes in tissue homogenates. 23 8

Studies were carried out to determine the distribution of the following: (1) carbamoyl phosphate synthetase (EC 2.7.2.9), (2) ornithine carbamoyltransferase (EC 2.1.3.3), (3) argininosuccinate synthetase (EC 6.3.4.5), and (4) argininosuccinate lyase (EC 4.3.2.1) in soybean cells grown in suspension culture. Protoplasts were produced from the soybean cells by treatment with cellulase (EC 3.2.1.4) and pectinase (EC 3.2.1.15); the protoplasts were then ruptured by osmotic shock with distilled water. This treatment was followed by differential centrifugation and sucrose density gradient centrifugation to isolate various organelle fractions including mitochondria and plastids. Examination of these fractions using specific enzyme assays showed that carbamoylphosphate synthetase and ornithine carbamoyltransferase were localized in a fraction found to be composed primarily of plastids. Argininosuccinate synthetase and argininosuccinate lyase appeared to be associated with either the cytosol or a membrane fraction in close association with the cytosol such as the endoplasmic reticulum or protoplast membrane.
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PMID:The localization within plant cells of enzymes involved in arginine biosynthesis. 56 67

We present a diagnostic and therapeutic protocol designed to prevent clinical expression of inborn errors of urea synthesis in the neonatal period, and discuss the long-term developmental outcome of survivors. The families of 32 infants, among 43 identified prenatally as being at risk for a urea cycle disorder, chose to have their infants treated according to a diagnostic and therapeutic protocol, beginning at birth. The therapy was effective in avoiding neonatal hyperammonemic coma and death in seven patients with carbamoyl phosphate synthetase deficiency, argininosuccinate synthetase deficiency, and argininosuccinate lyase deficiency. When treated prospectively, five of eight patients with ornithine transcarbamylase deficiency avoided severe hyperammonemia and survived the neonatal period. Two patients with carbamoyl phosphate synthetase deficiency and two with ornithine transcarbamylase deficiency have subsequently died; three additional patients with the latter disorder have received orthotopic liver transplants. Our experience suggests that these surviving patients have had a more favorable neurologic outcome than patients rescued from neonatal hyperammonemic coma. However, all of them require a burdensome medical regimen and may have handicaps that include impairment of development and recurrent episodes of hyperammonemia. Further, those with deficiency of carbamoyl phosphate synthetase or ornithine transcarbamylase have a high mortality rate.
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PMID:Prospective treatment of urea cycle disorders. 172 Apr 58

The arcABC operon of Pseudomonas aeruginosa encodes arginine deiminase, catabolic ornithine carbamoyltransferase and carbamate kinase, respectively. We have determined the nucleotide sequences of the arcA and arcC genes. The arcA open reading frame specifies a polypeptide of 46.3 kDa. The same molecular mass was obtained for the subunit of purified arginine deiminase after electrophoresis under denaturing conditions. The N-terminal amino acid sequence of arginine deiminase was in agreement with the corresponding nucleotide sequence. The native arginine deiminase had an estimated molecular mass of 175-180 kDa, suggesting a tetrametric structure. The enzyme was activated by Mg2+ or Mn2+ and strongly inhibited by Zn2+. The apparent Km for L-arginine was 0.04 mM in the presence of Mg2+ and 0.47 mM without Mg2+. The arcC open reading frame codes for a 33-kDa protein, confirming the molecular mass previously reported for the subunit of carbamate kinase. The translation-initiation site of arcC was determined by deletion mapping. Two regions of dyad symmetry found between arcA and arcC might stabilize the putative arcABC transcript in the upstream (arcA) region; this might contribute to the high level of arcA expression as compared to the moderate level of arcC expression. Carbamate kinase had 37% sequence similarity (and 13.5% identity) with the C-terminal part of carbamoyl-phosphate synthetase (large subunit) from Escherichia coli. Arginine deiminase had no apparent similarity with argininosuccinate lyase. Thus, the arcA and arcC genes do not appear to be closely related to arginine biosynthetic genes, whereas it had previously been shown that the arcB gene has a high degree of identity with the arginine biosynthetic argF genes of P. aeruginosa and E. coli.
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PMID:Sequence analysis and expression of the arginine-deiminase and carbamate-kinase genes of Pseudomonas aeruginosa. 253 2

Foetal hepatocytes obtained from rats at different stages were cultured in order to investigate the inducibility of the five urea-cycle enzymes by glucagon and dibutyryl cyclic AMP (Bt2cAMP). When 18.5-day-old hepatocytes were cultured for 3 days with 10(-7) M glucagon, the activities of carbamoyl phosphate synthetase (CPS), argininosuccinase (ASL) and arginase were increased by 1.4-, 1.8- and 1.9-fold, respectively, as compared to controls. These effects were mimicked by 10(-4) M Bt2cAMP, but the activities of ornithine transcarbamylase (OTC) and argininosuccinate synthetase (ASS) were never changed by the addition of these compounds. Hepatocytes cultured at earlier stages were not responsive to glucagon unless dexamethasone was added simultaneously, suggesting that this steroid might induce some steps necessary for glucagon action. Bt2cAMP was effective as early as day 16.5 without requiring the presence of steroids. In addition, the effect of the cyclic nucleotide appeared additive or synergistic with that of dexamethasone. The simultaneous addition of actinomycin D did not affect the glucagon-induced increase in enzyme levels, thus suggesting a post-transcriptional effect of the hormone on the foetal enzyme activities. Insulin itself did not have any effect on the basal level of the enzyme activities and had only a moderate inhibitory effect on glucagon-induced ASL activity. This slight effect of insulin is in contrast with the marked inhibitory effect of dexamethasone on this enzyme activity that we described previously.
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PMID:Induction of the five urea-cycle enzymes by glucagon in cultured foetal rat hepatocytes. 332 26

We have confirmed that arginine-deficient diets increase the liver activities (units per 100 g) of the first four arginine biosynthetic enzymes of the urea cycle in Wistar rats, but not the activity of arginase. In contrast, rat liver cells cultured in monolayers for 48, 72 or 96 h in arginine-free L-15 or minimum essential medium showed no changes in carbamoyl-phosphate synthase (EC 6.3.4.16), ornithine transcarbamylase (EC 2.1.3.3), argininosuccinate synthase (EC 6.3.4.5), argininosuccinase (EC 4.3.2.1) or arginase (EC 3.5.3.1) activities. The arginine content of the cells grown on deficient medium was 36% of that of cells grown on 2.9 mM arginine-sufficient L-15, yet the urea excretion rate into the medium was reduced to 7% of the rate in control cells and the excretion of orotic acid was 400% of that in control cells. A Morris rat hepatoma cell line, 7800C1, which maintains activities of all five urea cycle enzymes, showed no consistent increases in the activities of the first four enzymes when the arginine in the medium was varied between 0 and 2 mM. Thus, in spite of severe arginine deficiency, cultured rat liver cells and hepatoma cells do not show the derepression-like response seen by other investigators when nonliver cells were cultured in arginine-deficient media. The difference between in vivo and in vitro effects of arginine deficiency on urea cycle activities remains unexplained.
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PMID:Differing effects of arginine deficiency on the urea cycle enzymes of rat liver, cultured hepatocytes and hepatoma cells. 368 73

The activity changes of the urea-cycle enzymes were monitored in cultured foetal hepatocytes after dexamethasone and insulin treatments. Addition of dexamethasone induced the development of carbamoyl-phosphate synthetase, argininosuccinate synthetase, argininosuccinase and arginase activities as soon as day 16.5 of gestation. When insulin was added together with dexamethasone, it markedly inhibited the steroid-induced increase in carbamoyl-phosphate synthetase, argininosuccinate synthetase and argininosuccinase activities.
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PMID:Role of dexamethasone and insulin on the development of the five urea-cycle enzymes in cultured rat foetal hepatocytes. 388 87

Glutamine synthetase and glutamine- and acetylglutamate-dependent carbamoyl-phosphate synthetase, both of which are present in high concentrations in liver of urea-retaining elasmobranchs, have been found to be located exclusively in the mitochondria in liver from the representative elasmobranch Squalus acanthias. This observation is consistent with the view that the function of this unique carbamoyl-phosphate synthetase is related to urea synthesis, and that the initial nitrogen-donating substrate for urea synthesis in these species is glutamine rather than ammonia. The urea cycle enzymes, ornithine carbamoyltransferase and arginase, are also located in the mitochondria, whereas argininosuccinate synthetase and argininosuccinate lyase are located in the cytosol. Glutamine synthetase and arginase are mitochondrial enzymes in uricotelic species, but are normally found in the cytoplasm in ureotelic species. the properties of the elasmobranch arginase, however, are characteristic of arginases from ureotelic species (e.g. the Km for arginine is 1.2 mM, and the enzyme has an Mr congruent to 100,000).
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PMID:Subcellular location of glutamine synthetase and urea cycle enzymes in liver of spiny dogfish (Squalus acanthias). 612 10

The urea-synthesizing enzymes of human liver tissues, namely, carbamylphosphate synthetase (CPS, EC 2.7.2.2), ornithine transcarbamylase (OTC, EC 2.1.3.3), arginine synthetase system, argininosuccinase (ASase, EC 4.3.2.1), and arginase (EC 3.5.3.1) were measured between pre- and postnatal periods. Specimens from 67 autopsied human livers obtained from fetuses, premature infants, newborn infants, infants, children, and adults were examined. The mean activities of the enzymes showed an increased pattern for OTC and arginase at fetal life, whereas those of CPS, arginine synthetase system, and ASase of fetal livers showed no significant difference in each stage. Except for arginase, the other four enzyme activities were higher in the postnatal period than those in the fetal life. Arginase activities indicated maximal increase at a gestational age between 28 and 31 weeks and decreased in the postnatal life.
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PMID:A study of urea-synthesizing enzymes in prenatal and postnatal human liver. 738 44

1. The activities of enzymes of the urea cycle [carbamoyl phosphate synthetase, ornithine transcarbamoylase, argininosuccinate synthetase, argininosuccinase (these last two comprising the arginine-synthetase system) and arginase] have been measured in control, alloxan-diabetic and glucagon-treated rats. In addition, measurements were made on alloxan-diabetic rats treated with protamine-zinc-insulin. 2. Treatment of rats with glucagon for 3 days results in a marked increase in the activities of three enzymes of the urea cycle (carbamoyl phosphate synthetase, argininosuccinate synthetase and argininosuccinase). The pattern of change in the alloxan-diabetic group is very similar to that of the glucagon-treated group, although the magnitude of the change was much greater. 3. Comparison was made of the actual and potential rate of urea synthesis in normal and diabetic rats. In both groups the potential rate of urea production, as measured by the activity of the rate-limiting enzyme, argininosuccinate synthetase, slightly exceeds the actual rate of synthesis by liver slices in the presence of substrates. The relative activities of the actual and potential rates were similar in the two groups of animals, this ratio being 1:0.70. 4. In the alloxan-diabetic rats treated with protamine-zinc-insulin for 2.5 or 4 days there was a marked increase in liver weight. This was associated with a rise in the total hepatic activity of the urea-cycle enzymes located in the soluble fraction of the cell (the arginine-synthetase system and arginase) after 2.5 days of treatment. After 4 days of treatment the concentration of these enzymes/g. of liver decreased, and the total hepatic content then reverted to the untreated alloxan-diabetic value. 5. No effects of glucagon or of insulin in vitro could be found on the rate of urea production by liver slices. 6. The present results are discussed in relation to how far this pattern of change is typical of conditions resulting in a high urea output, and comparison has been made with other values in the literature.
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PMID:INFLUENCE OF PANCREATIC HORMONES ON ENZYMES CONCERNED WITH UREA SYNTHESIS IN RAT LIVER. 1434 1


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