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)

Glutamine-dependent carbamoyl-phosphate synthetase was purified about 2100-fold from the cytosol of rat liver using 30% (v/v) dimethyl sulfoxide and 5% (w/v) glycerol as stabilizers. Throughout the purification, aspartate transcarbamylase and dihydroorotase, the second and third enzymes of pyrimidine biosynthesis, were copurified with the synthetase. These three enzymes sedimented as a single peak with a sedimentation coefficient of 27 S in sucrose gradients containing the stabilizers, indicating their existence as a multienzyme complex. The aggregation states of the complex were analyzed by sucrose gradient centrifugation under conditions approximating those used for enzymatic assay and correlated with the kinetic properties of the synthetase. In the presence of 10% glycerol and 10 mM MgATP(2-) at 18 degrees, the synthetase showed high activity and the three enzymes sedimented as a single peak with a coefficient of 25 S. The three enzymes also existed as a complex with the same coefficient when 50 muM PP-ribose-P was added in place of MgATP(2-), the sedimentation coefficient of the complex shifted to 28 S, indicating alteration in its molecular shape, rather than size. With 10% glycerol alone, the complex partially dissociated and the synthetase activity appeared in three peaks with coefficients of 26, 19, and 9 S (carbamoyl-phosphate synthetases (CPSase) a, b, and c, respectively). CPSases a, b, and c, thus obtained, were all sensitive to regulation by UTP and PP-ribose-P, but they differed MgATP(2-) (5.1, 4.8, AND 1.7 mM for CPSases a and b, and the enzyme within the original complex, respectively) and in their sensitivities to effectors. These results suggest that the aggregation may modify the catalytic and regulatory properties of the synthetase; Attempts to reassociate the components were unsuccessful.
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PMID:Aggregation states and catalytic properties of the multienzyme complex catalyzing the initial steps of pyrimidine biosynthesis in rat liver. 114 71

Interactions of CRP with various substrates in the presence of human serum have been shown to result in efficient activation of C components C1-C5. We now report the ability of CRP to initiate C-dependent hemolysis. For this purpose CRP was isolated by affinity chromatography using pneumococcal CPS and gel filtration; its purity was established by several criteria. Erythrocytes were coated with CPS (E-CPS) and passively sensitized with CRP. C-dependent lysis of these cells was observed upon the addition of suitably absorbed human serum, and the efficiency of hemolysis compared favorably with that initiated by rabbit IgG anti-CPS antibody. CRP also sensitized E-CPS for lysis by guinea pig C; partial lysis was seen when C4-deficient guinea pig serum was used, suggesting that CRP also shares with antibody the ability of CRP to fully activate the C system and provide further evidence for a role for CRP similar to that of antibody in the initiation and modulation of inflammatory reactions via the complete system.
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PMID:Interactions of C-reactive protein with the complement system. III. Complement-dependent passive hemolysis initiated by CRP. 119 48

To study the regulation of transcription of the carbamoyl-phosphate synthase (glutamine-hydrolyzing)/aspartate carbamoyltransferase/dihydroorotase (CAD) gene from the Syrian hamster, Mesocricetus auratus, we developed a homologous in vitro transcription system on the basis of nuclear extract from Syrian hamster kidney cells. We optimized the reaction temperature and the concentrations of DNA template, KCl, and MgCl2 simultaneously with the response surface method and found an unusually low temperature optimum of 20 degrees C. We therefore investigated whether CAD transcription in vitro depended on a heat-labile component of nuclear extract. Preincubating extract alone at 30 degrees C reduced transcription from the CAD promoter but not from the major late promoter of adenovirus 2. The formation of stable initiation complexes at the CAD promoter was diminished in heat-treated extract; run-off transcripts, however, accumulated at the same rate as in untreated extract. The heat sensitivity of complex formation correlated with the heat sensitivity of DNA binding by transcription factor Sp1, which binds to two sites in the CAD promoter; moreover, both preformed initiation complexes and DNA-bound Sp1 were heat-resistant. Adding purified Sp1 to heat-treated extract restored complex formation. We propose that Sp1 activates CAD transcription by stabilizing initiation complexes at the CAD promoter.
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PMID:Heat sensitivity and Sp1 activation of complex formation at the Syrian hamster carbamoyl-phosphate synthase (glutamine-hydrolyzing)/aspartate carbamoyltransferase/dihydroorotase promoter in vitro. 134 30

The effects of unilateral nephrectomy (UN) and streptozotocin (STZ) diabetes on the activities of enzymes involved in uridine and cytidine synthesis in early renal growth (3-14 days after stimulus to growth) have been compared. Measurements were also made of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) and of glucose 6-phosphate (G6P), UDP-glucose, and glycogen, in relation to phosphoribosyl pyrophosphate, ribonucleotide, and complex carbohydrate formation. There were striking differences in the activities of CTP synthetase, G6PDH, and 6PGDH in the two conditions, with a three-fold increase in all three enzymes at 3 and 5 days and a two-fold increase above basal values at 14 days of STZ diabetes. The UN group showed no significant change in CTP synthetase at any stage and the activity of G6PDH and 6PGDH only kept pace with renal growth. Changes in routes of uridine synthesis were less marked, with a more rapid rise in carbamoyl-phosphate synthetase (glutamine) and a lesser response of dihydroorotate dehydrogenase in the UN relative to the STZ-diabetic groups. The enzymes of complex II and of uracil phosphoribosyltransferase showed essentially similar patterns during renal hypertrophy in UN and STZ diabetes. The parallel increase in CTP synthetase, G6PDH, and 6PGDH in the kidney in diabetes, also known to increase in growth situations in hepatomas and in renal tumors, is discussed in relation to hormone signals involved in renal growth. The importance of the concentration of CTP, and thus of CTP synthetase, in the CTP-cytidyltransferase reaction, an enzyme with a high Km for CTP, makes the present observation of the striking increase in CTP synthetase in STZ diabetes of particular interest in relation to phosphatidylcholine formation and hormone signal transduction.
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PMID:Uridine and cytidine nucleotide synthesis in renal hypertrophy: biochemical differences in response to the growth stimulus of diabetes and unilateral nephrectomy. 138 Dec

A randomized study was conducted in 40 allogeneic marrow recipients to compare the immunogenicity of two Haemophilus influenzae type b (Hib) vaccines (either the Hib capsular polysaccharide [Hib-CPS] or tetanus toxoid-conjugated Hib-CPS [Hib-CPS-T]). A second injection consisted of Hib-CPS-T. Before immunization, 3 patients had serum antibody levels > 1 microgram/mL. After the first injection, the response was better after Hib-CPS-T than after Hib-CPS but lower than in normal subjects; a number of patients lacked any IgG antibody response, especially after Hib-CPS. Of patients who received two injections of Hib-CPS-T, 85% achieved an antibody concentration > or = 1 microgram/mL. Hib-CPS-T induced a response in IgG2-deficient patients whereas Hib-CPS alone did not. IgG antibodies predominantly belonged to the IgG1 subclass. The antibody response was better in patients immunized late after graft. This study shows that Hib-CPS-T is more immunogenic than Hib-CPS in marrow recipients.
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PMID:Immunogenicity of Haemophilus influenzae type b conjugate vaccine in allogeneic bone marrow recipients. 140 13

Some of the ammonia produced by hydrolysis of urea by Ureaplasma urealyticum is channelled into an anabolic pathway with resultant 'de novo' synthesis of citrulline. The organism appears to possess ornithine carbamoyltransferase and carbamoyl phosphate synthetase or some modified form of these enzymes.
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PMID:Urea-hydrolysis-dependent citrulline synthesis by Ureaplasma urealyticum. 145 99

Over the past 40 years, the American Cancer Society has led in large-scale, prospective studies of behavioral and environmental risk factors in association with cancer development. Through results of its 1952 study, cigarette smokers were found to have a 10-fold higher risk of lung cancer than nonsmokers. Cancer Prevention Study I (1959-1972) extended these results and also showed the relationship between age smoking began, depth of inhalation, smoking cessation, air pollution, body weight, etc., on all causes of death as well as specific cancer sites. Cancer Prevention Study II began in 1982 and after six years of follow-up has confirmed many earlier findings, and additionally has found: aspirin may be protective against colon cancer; persons reporting themselves to be heavy exercisers had higher standardized mortality ratios (SMR) for lung, colorectal, and pancreas cancer than moderate exercisers; more women who were long-term users of artificial sweeteners reported gaining weight during the past year than nonusers; diesel fume exposure elevated the risk of lung cancer among men ages 40-79; pesticide exposure was associated with an increased risk of multiple myeloma; and based on CPS II mortality rates, an estimated 250 million of the 1.25 billion persons living in developed countries will die because they smoke.
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PMID:Cancer Prevention Study II. The American Cancer Society Prospective Study. 147 48

Measurements have been made of the activities of the enzymes of the de novo and salvage pathways of pyrimidine synthesis (carbamoyl phosphate synthetase II (glutamine) (EC 6.3.5.5); dihydroorotate dehydrogenase (EC 1.3.99.11); the overall activity of Complex II (orotate phosphoribosyl pyrophosphate transferase (EC 2.4.2.10) and orotidine 5-phosphate decarboxylase (EC 4.1.1.23); uracil phosphoribosyltransferase (EC 2.4.2.9)) in the mammary gland of rats at different stages of the lactation cycle and the effects of diabetes on the activity of these enzymes in lactation have been studied. From a consideration of the changes in enzyme activities and the changes in the tissue concentration of phosphoribosyl pyrophosphate, an activator of the de novo pathway and substrate for both the de novo and salvage routes, it is concluded that the de novo pathway is the major route of pyrimidine synthesis in mammary tissue. Diabetes decreases the activity of the enzymes of the de novo pathway; the effects are particularly marked for Complex II. The present results on pyrimidine synthesis are compared to the pattern for purine synthesis previously published.
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PMID:Pyrimidine nucleotide synthesis in the rat mammary gland: changes in the lactation cycle and effects of diabetes. 147 92

Ammoniacal silver solutions give striking impregnation of Alzheimer's disease (AD) lesions if sections are pretreated with copper sulfate and hydrogen peroxide. In contrast to most silver impregnation methods, no staining of normal neurites is obtained, and senile plaques (SPs), neurofibrillary tangles (NFTs), and neuropil threads (NTs) are strongly stained in black against a clear background. A sodium acetate wash interposed between the copper sulfate and hydrogen peroxide resulted in suppression of the staining of amyloid lesions. This variant of the basic procedure (CPS-II method), maintains the capacity of the latter (CPS-I method) to strongly impregnate NFTs and NTs. In addition, it clearly delineates the dystrophic neurites of SPs obscured by the strong argyrophilia of the amyloid deposits seen in CPS-I stains. NTs are strongly impregnated with both CPS-I and CPS-II methods and are unmasked from normal neurites, which remain unstained. The staining can be abolished by pretreatment with formic acid and erased with a brief wash in sulfochromic acid. Destained sections can be restained with either method or with immunoperoxidase procedures. CPS staining of previously immunostained tissues produces marked intensification of the diaminobenzidine reaction product. In AD brains, the immunostaining is markedly enhanced and selective when the silver procedure is preceded by formic acid treatment. The selectivity and high sensitivity of the procedure may be useful as a diagnostic tool and of value to study the biogenesis and natural evolution of the brain lesions of AD.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The copper-peroxide-silver method: a highly sensitive procedure for the demonstration of Alzheimer's disease lesions and for signal intensification in immunocytochemistry. 149 51

We have measured the 'core' mammalian carbamoyl-phosphate synthetase II (CPSII) activity, using NH4Cl as the nitrogen-donating substrate and trapping carbamoyl phosphate as urea through its reaction with ammonium ions. When ATP and magnesium ion concentrations are close to those found in the cell, the substrate saturation curves for ammonia and bicarbonate are hyperbolic, giving Km (NH3) values of 166 microM at high ATP concentrations and 26 microM at low ATP concentrations, while the Km (bicarbonate) is 1.4 mM at both ATP concentrations used. These values for the Km (NH3) are lower than previously reported for CPS II, and closer to the values for the mitochondrial counterpart. The Km for ammonia and bicarbonate are not altered by phosphorylation of the multienzyme polypeptide CAD, which contains the first three enzyme activities of pyrimidine biosynthesis. The CPS II activity is lower with an excess of either ATP or magnesium ions, causing the apparently sigmoid dependence of activity upon ATP concentration to be enhanced at low concentrations of free magnesium ions. The feedback inhibitor, UTP, acts by stabilising a state with a low affinity for magnesium ions and for ATP. In the presence of the activator, 5-phosphoribosyl diphosphate (PRibPP), the enzyme has a higher affinity for magnesium ions and thus the ATP dependence of the activity is hyperbolic. Phosphorylation of CAD similarly activates the CPS II enzyme by increasing the affinity for magnesium ions and by pushing the equilibrium away from the low-affinity UTP-stabilised state. Using our improved assay procedure, we observe a very large activation by PRibPP of carbamoylphosphate synthesis at low concentrations of magnesium ions, and we find that unlike UTP, the activator PRibPP is able to act on the phosphorylated enzyme.
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PMID:Regulation of the mammalian carbamoyl-phosphate synthetase II by effectors and phosphorylation. Altered affinity for ATP and magnesium ions measured using the ammonia-dependent part reaction. 149 69


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