Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
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.
 ...
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.
 ...
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.
 ...
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.
 ...
PMID:Sequence analysis and expression of the arginine-deiminase and carbamate-kinase genes of Pseudomonas aeruginosa. 253 2

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.
 ...
PMID:Differing effects of arginine deficiency on the urea cycle enzymes of rat liver, cultured hepatocytes and hepatoma cells. 368 73

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).
 ...
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.
 ...
PMID:A study of urea-synthesizing enzymes in prenatal and postnatal human liver. 738 44

Urea is an important reutilizable nitrogen source for the ruminant and is mainly synthesized through the urea cycle in the liver. The cycle is undertaken by 5 enzymes: carbamoyl phosphate synthetase (CPS), ornithine transcarbamoylase (OTC), arginino-succinate synthetase (AS), argininosuccinate lyase (AL), and arginase. The purpose of this study was to investigate changes in the activity of the enzymes and mRNA expression, given that previous observations have indicated an increase in plasma urea concentrations with age in Holstein calves. First, plasma concentrations of metabolites and hormones were determined in calves at 1, 3, 8, 13, and 19 wk of age (n = 4, weaned at 6 wk of age). The plasma concentration of urea drastically increased after weaning (P < 0.001). The plasma concentration of glucose was lowest at 8 wk. The plasma concentration of IGF-I gradually increased with age, although those of NEFA, glucagon, and cortisol decreased (P < 0.001). Concentrations of triglyceride, alpha-amino nitrogen, growth hormone, and insulin did not change significantly with age of the calf. Next, using the liver tissues taken from calves at 2, 13, and 19 wk of age (n = 4 to 6 at each time point, weaned at 6 wk of age), we measured the activity and mRNA expression of the enzymes by biochemical methods and quantitative reverse transcription-PCR, respectively. The activities of CPS (P < 0.001), OTC (P = 0.001), and AS (P = 0.015) increased with age, whereas AL (P = 0.003) decreased. Although mRNA expression was decreased with age for AL (P = 0.002) and arginase (P = 0.007), no significant change was observed for CPS, OTC, or AS mRNA expression. We conclude that the increased urea production in the liver may be explained not only by an increase in the activities of the urea cycle enzymes, but also by increased ammonia production by rumen fermentation and gluconeogenesis from amino acids around weaning time.
 ...
PMID:Changes of activity and mRNA expression of urea cycle enzymes in the liver of developing Holstein calves. 1834

The present work reports the activities of urea cycle enzymes during the ontogenic development of the teleost pacu (Piaractus mesopotamicus). Urea cycle enzymes from the kidney and liver of adult fish were compared with those from the fish's embryonic phases. Samples were evaluated over all phases of embryonic development, the larval period and alevin. Ammonia and urea concentrations were determined during embryogenesis and in the plasma of adult fish. Except for carbamoyl phosphate synthetase-III (CPS-III), all enzymes of the urea cycle were expressed in the larvae and alevins as well as in the liver and kidney of adult fish. In spite of the low level of activity of the ornithine urea cycle (OUC) enzymes compared to those in mammals, and the low levels of tissue urea concentration compared to ammonia, the ureogenesis was evaluated in pacu. Ammonia seems to be the main nitrogenous waste during embryonic development. In this phase glutamine synthetase (GS) may play a role in ammonia detoxification, and the OUC enzymes can be individually involved in functions other than urea production. The presence of ornithine carbamoyl transferase (OCT) in all developmental phases of pacu and in the adult liver and kidney suggests that this enzyme is performing different metabolic pathways. OCT in the kidney, wherein the activity is less than in the liver, should work in the biosynthesis of polyamines and control the arginine plasma concentration given that renal arginase and argininosuccinate synthetase-argininosuccinate lyase are more active than from the liver. We suppose that OCT during the embryogenesis is a control step regulating the cellular concentration of ornithine for polyamines synthesis.
 ...
PMID:Urea cycle enzymes through the development of pacu (Piaractus mesopotamicus): the role of ornithine carbamoyl transferase. 1864 31

The gulf toadfish (Opsanus beta) is a facultatively ureotelic fish that excretes primarily urea under conditions of crowding or confinement. To examine the relationship between ammonia production, urea production and the ornithine-urea cycle (O-UC) enzyme activity and mRNA expression, we subjected toadfish to two-day and seven-day crowding regimes. Plasma cortisol levels were measured and liver tissue was assayed for ammonia and urea concentrations. Liver glutamine synthetase (GS), carbamoyl phosphate synthetase III (CPS), ornithine carbamoyl transferase (OCT) and arginase (ARG) activities were also measured. Quantitative PCR was utilized to determine liver GS, CPS, OCT, ARG, argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL) mRNA expression. Hepatic ammonia concentrations decreased with increased duration of crowding whereas liver urea and circulating cortisol levels increased. An elevation in enzyme activity with increased duration of crowding was observed for all four O-UC enzymes examined. By contrast, mRNA expression was variable for the O-UC enzymes and only CPS and ASS had mRNA expression levels that were elevated in crowded fish. These results suggest that the activities of O-UC enzymes are better predictors for urea production than O-UC enzyme mRNA expression levels.
 ...
PMID:Effects of crowding on ornithine-urea cycle enzyme mRNA expression and activity in gulf toadfish (Opsanus beta). 1961 32


1 2 Next >>