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)

The mitochondrial matrix subfractions from rat liver, kidney cortex, brain, heart, and skeletal muscle were isolated and their protein components were resolved by two-dimensional polyacrylamide gel electrophoresis, revealing between 120 and 150 components for each matrix subfraction. Excellent resolution was obtained utilizing a pH 5 to 8 gradient in the first dimension and in 8 to 13% exponential acrylamide gradient in the second dimension, increasing the number of mitochondrial matrix proteins observed 3-fold over one-dimensional systems. Protein components tentatively identified by co-migration with pure enzymes and by known tissue distributions are carbamoyl-phosphate synthetase (EC 2.7.2.5), ornithine transcarbamylase (EC 2.1.3.3), glutamate dehydrogenase (EC 1.4.1.3), pyruvate carboxylase (EC 6.4.1.1), citrate synthase (EC 4.1.3.7), fumarase (EC 4.2.1.2), aconitase (EC 4.2.1.3), alpha-ketoglutarate dehydrogenase (EC 1.2.4.2), dihydrolipoyl transsuccinylase (EC 2.3.1.12), lipoamide dehydrogenase (EC 1.6.4.3), glutamate-aspartate aminotransferase (EC 2.6.1.1), and the two subunits of pyruvate dehydrogenase (EC 1.2.4.1). Protein components unambiguously identified by peptide mapping are citrate synthase, aconitase, and pyruvate carboxylase. The inner membrane subfraction from rat liver mitochondria was also resolved two dimensionally; the alpha and beta subunits of ATPase (F1) (EC 3.6.1.3) were identified by peptide mapping.
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PMID:Resolution of rat mitochondrial matrix proteins by two-dimensional polyacrylamide gel electrophoresis. 44 63

The infusion of ether anesthaetized rats with 0.2 M (1 mmols in total) ammonium acetate or glutamine were compared with the infusion of 0.2 M NaCl. The levels of circulating glucose, amino acids, lactate, urea and ammonium were measured as well as liver glycogen and tissue amino acids and the liver and muscle activities of carbamoyl phosphate synthetases I and II, glutamate dehydrogenase, glutamine synthetase and adenylate deaminase. Neither treatment altered the glucose and glycogen homeostasis. The infusion of ammonium did not result in increases in circulating ammonium, but resulted in increased circulating urea after a short delay; the infusion of glutamine resulted also in urea production but much later on. Glutamine infusion also resulted in increased tissue free amino-acid levels. There was little alteration in enzyme activities, except for decreased glutamine synthetase and adenylate deaminase activity in muscle of glutamine-infused rats and higher tissue carbamoyl phosphate synthetase II. The results agree with a fast removal of infused ammonium, and maintenance of glutamine, with their channeling towards urea production at a rate comparable with that of infusion, that did not alter significantly the homeostasis of the experimental animals.
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PMID:Glutamine and ammonium handling by anaesthetized rats. 247 81

Male mice carrying the spfash mutation have 5-10% of the normal activity of ornithine carbamoyltransferase, yet are only slightly hyperammonaemic and develop quite well. A study of liver mitochondria from normal and spfash males showed that they differ in important ways. (1) The spfash liver contains about 33% more mitochondrial protein per g than does normal liver. (2) The specific activities of carbamoyl-phosphate synthetase (ammonia) and glutamate dehydrogenase are about 15% lower than normal in mitochondria from spfash mice, whereas those of beta-hydroxybutyrate dehydrogenase and cytochrome oxidase are 22% higher and 30% lower respectively. (3) In the presence of 10 mM-ornithine and the substrates for carbamoyl phosphate synthesis, coupled and uncoupled mitochondria from spfash mice synthesize citrulline at unexpectedly high rates, about 25 and 44 nmol/min per mg respectively. Though these are somewhat lower than the corresponding rates obtained with normal mitochondria, the difference does not arise from the deficiency in ornithine carbamoyltransferase, but from the lower carbamoyl-phosphate synthetase activity of the mutant mitochondria. (4) At lower external [ornithine] (less than 2 mM), a smaller fraction of the carbamoyl phosphate synthesized is converted into citrulline in spfash than in normal mitochondria. These studies show that what appears to be a single mutation brings about major adaptations in the mitochondrial component of liver. In addition, they clarify the role of ornithine transport and of protein-protein interactions in citrulline synthesis in normal mitochondria.
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PMID:Altered enzyme activities and citrulline synthesis in liver mitochondria from ornithine carbamoyltransferase-deficient sparse-furash mice. 292 15

Low molecular weight phosphoryl compounds, such as carbamoyl phosphate, 2,3-diphosphoglycerate and phytic acid protect, to different extents, mitochondrial and cytosolic proteins such as ornithine transcarbamoylase (OTC), carbamoyl phosphate synthetase (CPS), glutamate dehydrogenase (GDH) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), from proteolytic inactivation (rat liver lysosomal extracts, pronase, elastase). Given the wide variety and common occurrence of low molecular weight reagents such as typified here, it seems that this kind of inhibition may be important in the regulation of protein turnover. Regulation of intracellular proteolysis can also occur via the proteolytic systems. Immunocytochemical procedures for mitochondrial enzymes (CPS, GDH, OTC), show intracellular homogeneity, but intercellular heterogeneity in rat liver, compatible with a role of the autophagic-lysosomal system in degrading these proteins. However, degradation of short-lived proteins occurs by other mechanisms. Using centrifugation of cultured cells, we find that the Golgi apparatus takes part in the degradation of these proteins, probably by controlling the traffic of proteins or proteases to the degradation site.
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PMID:Regulatory mechanisms of intracellular proteolysis in mammalian cells. 355 76

Carbamoyl phosphate synthetase I (CPS-I) is the most abundant protein of rat liver mitochondria. Biochemical measurements in liver homogenates have shown that the liver from rats fed a high-protein diet contains more CPS-I per gram tissue protein than controls. However, there is no information on changes in the intact tissue at the cellular and mitochondrial level. Therefore, monoclonal antibodies to beef liver CPS-I were produced by the hybridoma technique. Four clones, C-241/1A, B, C, and D secreted immunogammaglobulin (IgG) IgG1. Using C-241/C, we measured by electron microscopy immunogold procedures the labeling of CPS-I in mitochondria from liver of rats fed high protein (casein, 50 and 80% of total food intake) diets. CPS-I (expressed as gold particles/micron2 of mitochondrial cross-sectional area) was greater than in mitochondria from control rats (20% casein diet), whether the rats were fed for 1, 6, or 14 months on the high-protein diets. The immunocytochemical measurements shown here demonstrate that the increase in the level of CPS-I in high-protein diets is a reflection of both the larger number of CPS-I molecules per mitochondrial area and the larger proportion of the total hepatocyte volume occupied by mitochondria. Similar measurements were carried out with glutamate dehydrogenase (GDH) using previously characterized monoclonal antibodies. No differences in GDH labeling were found with high-protein diets. Interestingly, when mitochondria from hepatocytes of rats fed a high-protein diet were divided into two subpopulations on the basis of mitochondrial cross-sectional size (i.e., greater or less than 0.7 micron2), the large mitochondria had 1.2 times more CPS-I and 0.8 times less GDH than the small mitochondria nearby.
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PMID:Monoclonal antibodies used in immunocytochemical localization by electron microscopy of carbamoyl phosphate synthetase I in liver from rats fed high-protein diets. 359 70

Acetylglutamate in HClO4 tissue extracts is first separated from glutamate by ion exchange. It is then deacylated with aminoacylase, and the resulting glutamate, after adsorption to and elution from an AG 50 column, is quantitated by a fast-HPLC method using o-phthaldialdehyde precolumn derivatization, separation in a C18 reverse-phase column, and fluorescence detection. A linear response is obtained up to 2 nmol, the detection limit is 5 pmol, and the method is suitable for assay in 1 mg liver tissue and thus for needle biopsies. When samples were analyzed by this procedure and by earlier procedures based upon detection of glutamate with glutamate dehydrogenase or upon activation of carbamoyl phosphate synthetase the results were similar. The method, which is highly specific, compares favorably in sensitivity, precision, and accuracy with all other published procedures. Using this assay, no acetylglutamate has been found in chicken liver and rat kidney.
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PMID:Determination of N-acetyl-L-glutamate using high-performance liquid chromatography. 399 35

The activities of a number of enzymes in rat liver have been measured at different times during adulthood and senescence and expressed as a percentage of maximal activity that can be attained after hormonal stimulation. Three different profiles can be detected. Type I profile shows decreasing activities during adolescence (1--3 months of age), increasing activities during adulthood (4--12 months of age) and relatively high activities thereafter. Enzymes of this group are carbamoyl-phosphate synthase and arginase; DNA content shows the same pattern. Type II profile shows decreasing activities during adolescence and relatively low activities thereafter. Enzymes of this group are tyrosine aminotransferase, glucose-6-phosphatase, and glucokinase. Type III profile shows relatively high activities during adolescence, adulthood and senescence. Enzymes of this group are ornithine transcarbamoylase, glutamate dehydrogenase and hexokinase. Some enzymes are constant with age in females, but slowly decrease in activity with age in males; decreasing levels of androgens and possibly also thyroid hormones can explain this decrease in males. Decreasing activities of carbamoyl-phosphate synthase and arginase during adolescence can be attributed to a depressant effect of gonadal hormones. The difference between relatively high and relatively low basal activities of enzymes in adult and senescent rats corresponds with their relatively long and short half-lives, respectively. This relation implicates a similar rate of synthesis of glucocorticosteroid hormone-dependent enzymes.
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PMID:Changes in the control of enzyme clusters in the liver of adult and senescent rats. 611 95

Enzyme activities and DNA content have been measure in axolotl liver during the metamorphic period (4-8 months after spawning). Three different types of enzyme activity profiles were observed. In the type I profile (carbamoyl-phosphate synthase, arginase, ornithine transcarbamoylase, and glutamate dehydrogenase) enzyme activity is high in the youngest animals studied, and shows a minimum at 5 months followed by a maximum at 8 months of age. Thereafter activities do not change or slightly decrease. In the type II profile (tyrosine aminotransferase, glucose-6-phosphatase) enzyme activity shows a peak at 5 months of age and is low thereafter. Hexokinase, the enzyme with a type III profile, shows high activity throughout the metamorphic period. DNA content remains high throughout the metamorphic period but decreases 50% between 9 and 12 months of age, probably due to an increase in the size of the hepatocytes. No glucokinase activity was detected. High activities of cluster II enzymes represent early metamorphic events, while the rising part of cluster I is associated with late metamorphic events. The apparent molecular specific activity increases during natural development between 5 and 9 months of age, or precociously, upon thyroid hormone treatment. This change in apparent molecular specific activity is correlated to the advent of ureotelism.
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PMID:Enzyme clusters during the metamorphic period of Ambystoma mexicanum: role of thyroid hormone. 612 71

The half-life of mitochondrial adenosine triphosphatase and the relative rate constants of protein degradation for several fractions of rat liver have been measured by the double-isotope technique. It has been shown that the apparent turnover rates of some mitochondrial enzymes, far apart in size, such as carbamoyl phosphate synthetase, glutamate dehydrogenase and malate dehydrogenase, are not related to molecular weight or to size of subunits. In view of the possibility that mitochondrial proteins are degraded by different mechanisms, it was of interest to determine the half-life of a protein tightly bound to the inner membrane such as adenosine triphosphatase. The rate constants of degradation for rats fed a basal diet and injected at three-day intervals with isotopic leucine were: homogenate, kd = 0.195 days-1; mitochondria, kd = 0.135 days-1; cytosol, kd = 0.140 days-1; microsomes, kd = 0.28 days-1; ATPase, kd = 0.275 days-1. The rate constants of the cellular fractions of liver of rats fed a high protein diet did not change or showed a small increase, compared with those of animals fed the basal diet, while those from rats on the protein-free diet showed a decrease. The rate constant for adenosine triphosphatase showed an increase with high-protein and a decrease with protein-free diet. A procedure for the purification of ATPase from a single liver of a rat is described.
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PMID:Turnover of adenosine triphosphatase from rat liver mitochondria. Effect of high-protein and low-protein diets. 621 5

The role of glucocorticosteroid and thyroid hormone and of glucagon and insulin in the pre- and postnatal developmental formation of carbamoyl-phosphate synthase, ornithine transcarbamoylase, arginase, glutamate dehydrogenase, tyrosine aminotransferase, glucose-6-phosphatase, hexokinase and glucokinase activities in rat liver was investigated. Glucocorticosteroids and a low insulin/glucagon ratio always stimulate formation of carbamoyl-phosphate synthase, ornithine transcarbamoylase, arginase, glutamate dehydrogenase, tyrosine aminotransferase and glucose-6-phosphatase, while glucocorticosteroids and a high insulin/glucagon ratio stimulate formation of glucokinase. Thyroid hormone stimulates the formation of carbamoyl-phosphate synthase, arginase and tyrosine aminotransferase only before birth, whereas it stimulates the formation of glutamate dehydrogenase and glucose-6-phosphatase both before and after birth. Ornithine transcarbamoylase activity is depressed after thyroid-hormone treatment before and after birth. DNA content is always decreased by glucocorticosteroids and increased by thyroid hormone. The effect of these hormones on hexokinase is complex, probably due to different responses of the constitutive isozymes. With the exception of the effects of thyroid hormone on carbamoyl-phosphate synthase, arginase and tyrosine aminotransferase before birth, which may be indirect, the responses of enzyme activities and DNA content to treatment with glucocorticosteroid hormones, glucagon, insulin and thyroid hormone are qualitatively the same in fetuses, neonates, sucklings, weanlings and adults. Thus, the developmental profiles of the enzyme clusters reflect the changing levels of the relevant hormones. The enzymes that are stimulated by glucocorticosteroids and the insulin/glucagon ratio show increases in enzyme activity perinatally and around weaning, and relatively low activities in between, while those enzymes that are additionally stimulated by thyroid hormone differ in exhibiting relatively high activities between birth and weaning.
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PMID:Multihormonal control of enzyme clusters in rat liver ontogenesis. II. Role of glucocorticosteroid and thyroid hormone and of glucagon and insulin. 702 60


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