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:6.4.1.1 (pyruvate carboxylase)
1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibroblast cultures from two individuals with biotin-responsive organicacidemia were found to have a pleiotropic deficiency of propionyl-CoA carboxylase, beta-methylcrotonyl-CoA carboxylase, and pyruvate carboxylase activities after growth in biotin limited culture medium, conditions which do not affect the carboxylase activities of normal cells. All three enzyme activities were restored to normal levels after transferring the mutant strains to biotin-rich medium. Both patients excreted abnormal levels of an array of metabolic intermediates, including beta-methylcrotonate, beta-hydroxyisovalerate, beta-hydroxypropionate, and lactate, which reflect metabolic blocks at all three carboxylase sites.14 mutants deficient in only propionyl-CoA carboxylase activity from patients with propionicacidemia and the two biotin-responsive strains were examined for complementation with seven previously mapped pcc mutants. No new pcc complementation groups were identified. Nine of the mutants were mapped to group pccA. The remaining 12 mutants mapped to pccBC or its B or C subgroups, confirming the complex nature of this group. The biotin-responsive mutants failed to complement each other but did complement mutants from all the pcc groups. Thus biotin-responsive organicacidemia is defined by a new complementation group, bio. The results obtained in this study suggest that the bio mutants have a defect of either biotin transport or a common holocarboxylase synthetase required for the biotin activation of all three mitochondrial carboxylases.
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PMID:Biotin-response organicaciduria. Multiple carboxylase defects and complementation studies with propionicacidemia in cultured fibroblasts. 11 3

The level of pyruvate carboxylase in Pseudmonas citronellolis is controlled by the carbon source of the growth medium. The activity of the enzyme is highest in cells grown on lactate or glucose and virtually absent in cells grown on malate or aspartate. Double labeling studies with 3H- and 14C-labeled leucine confirm that pyruvate carboxylase is synthesized in the presence of lactate but not in the presence of aspartate. The studies also show that coordinated regulation occurs at the level of the synthesis of the two polypeptides which make up pyruvate carboxylase in P. citronellolis, rather than at the stages of their assembly into protomers or the biotinylation of the apoenzyme. There is no evidence for control of the catalytic acitivity of the holoenzyme via effectors. In all other varieties of pyruvate carboxylase examined thus far, the enzyme appears to be constitutive with regulation accomplished either through effector modulation of holoenzyme activity (pyruvate carbox-lase from animal sources, yeast, several species of bacteria) or through control of the biotinylation of the apoenzyme by holocarboxylase synthetase (Bacillus stearothermophilus, yeast).
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PMID:The control of the synthesis of pyruvate carboxylase in Pseudomonas citronellolis. Evience from double labeling studies. 111 9

1. The multiple carboxylase deficiencies are inborn errors in the metabolism of biotin in which there is defective activity of propionyl CoA carboxylase, 3-methylcrotonyl CoA carboxylase and pyruvate carboxylase. 2. Two distinct disorders have been described. 3. In one the fundamental defect is in the enzyme holocarboxylase synthetase which catalyzes the molecular activation of the apocarboxylase proteins. 4. In the other the fundamental defect is in biotinidase which catalyzes the reutilization of biotin and may be involved in its digestion and intestinal absorption.
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PMID:Multiple carboxylase deficiency. 328 72

In biotin-responsive multiple carboxylase deficiency, a characteristic organic aciduria reflects in vivo deficiency of mitochondrial propionyl CoA carboxylase, 3-methylcrotonyl CoA carboxylase, and pyruvate carboxylase. A possible primary or secondary defect in biotin absorption leads to an infantile-onset syndrome, while abnormal holocarboxylase synthetase activity has been identified in the neonatal-onset form. While distinct mitochondrial and cytosolic holocarboxylase synthetase biotinylation systems may exist in avian tissues, the system has not been characterized in humans. Toward this objective, we studied the biotin dependence of a cytosolic carboxylase, acetyl CoA carboxylase (ACC), in cultured skin fibroblasts of both types of multiple carboxylase deficiency. ACC specific activities in control and infantile-onset cells were not distinguishable at all biotin concentrations: with decreasing biotin availability (+ avidin), there were only modest decrements in ACC activity in both these cell types. In contrast, there were pronounced declines of ACC activity in neonatal-onset (holocarboxylase synthetase-deficient) cells after growth in low biotin concentrations, and activity was undetectable in + avidin. ACC activity was rapidly restored with biotin repletion to biotin-starved holocarboxylase synthetase-deficient cells, and this restoration was largely independent of protein synthesis. The behavior of the cytosolic carboxylase, ACC, is in all these respects identical to that of the mitochondrial carboxylases, an observation consistent with the existence of similar biotinylation mechanisms in the two cell compartments. Further, the data support the notion that at least some components of the holocarboxylase synthetase system are shared by mitochondria and cytosol in humans, and are consistent with the suggestion that restoration of activity in biotin-depleted cells represents biotinylation of preexisting enzyme protein. The modest decrements in ACC activity in normal and infantile-onset cells may be related to the compromised epidermal integrity observed in that form of multiple carboxylase deficiency. Finally, ACC and mitochondrial carboxylase activities were compared in cells from mutants representing a spectrum of clinical severity. Cells from later-onset patients of intermediate clinical severity were ultimately classifiable as putative holocarboxylase synthetase-deficient cells on chemical criteria. Accurate etiologic classification cannot be based on clinical presentation alone, and biochemical studies should be performed on all patients. Accordingly, we propose a classification of multiple carboxylase deficiency based on biochemical criteria.
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PMID:Acetyl CoA carboxylase in cultured fibroblasts: differential biotin dependence in the two types of biotin-responsive multiple carboxylase deficiency. 614 28

A quantitative assay has been developed to measure holocarboxylase synthetase activity in cellular extracts. This assay was based on measuring the incorporation of [3H]biotin of high specific activity (4.3 Ci/mmol) into purified rat liver apopyruvate carboxylase. With this assay, holocarboxylase synthetase in 3T3-L1 mouse fibroblasts has been monitored. During the differentiation of this cell from a fibroblast to an adipocyte, holocarboxylase synthetase activity was found to increase threefold, while pyruvate carboxylase activity rose 20-fold. The results suggest a possible relationship between the activity of the holocarboxylase synthetase and the level of the biotin-dependent carboxylases within the mammalian cell. Utilizing digitonin fractionation. the intracellular distribution of this enzyme has also been examined. In the 3T3-L1 cell, the large majority (approximately 70%) of the total holocarboxylase synthetase activity was found in the cytosolic compartment.
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PMID:Regulation and intracellular localization of the biotin holocarboxylase synthetase of 3T3-L1 cells. 661 20

Three biotin-dependent enzymes, pyruvate carboxylase (PC), propionyl CoA carboxylase (PCC), and beta-methylcrotonyl CoA carboxylase (beta MCC), were biochemically characterized in fibroblasts from two patients with neonatal multiple carboxylase deficiency. Genetic complementation analyses indicated that both cell lines, designated lines 1 and 2, were deficient in the various carboxylase activities and belonged to the bio complementation group. The activities of the three carboxylases became normal when line 2 cells were incubated in medium supplemented with biotin (1 mg/l) for 24 hrs, whereas 4-6 days were required to achieve maximum activities of PC, PCC, and beta MCC (57%, 46%, and 29% of mean normal enzyme activity, respectively) in line 1 cells incubated in medium containing up to 10 mg/1 biotin. Furthermore, PC activity in line 2 continued to increase under apparent gluconeogenic conditions in culture, but not in line 1. Thermostability studies suggested that biotin stabilizes PC and beta MCC in both cell lines. PC in line 1 cells incubated with or without biotin was less stable than that in normal or line 2 cells, and the less than normal increase of enzyme activities in line 1, especially that of PC, may represent incomplete biotination. These results indicate that there is biochemical heterogeneity within the bio complementation group. Immunotitration with antibodies prepared against purified pig heart PCC demonstrated normal quantities of cross-reacting material in both lines and no differences in the amount of this material after incubation with supplemental biotin, despite the seven- to 20-fold increase in PCC activity. Thus, the increase in carboxylase activity in both bio lines appears to represent activation of rpe-existing apocarboxylase rather than de novo enzyme synthesis. The primary defect in this form of multiple carboxylase deficiency may be in a common holocarboxylase synthetase or in biotin transport. If the defect is in the synthetase, the differences noted between the two bio lines could be explained by a difference in the enzyme's Km for biotin.
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PMID:Biochemical characterization of biotin-responsive multiple carboxylase deficiency: heterogeneity within the bio genetic complementation group. 679 61

The Institution's experience with hypoglycemia in different types of organic acidemias, branched chain amino acidemia (MSUD), and disorders of fructose metabolism was reviewed retrospectively. The charts of 144 patients who were followed for 1-5 years were studied for the severity and frequency of hypoglycemia. The patients were mainly Saudi; however, 10-25% were from neighboring countries. Therefore, the observations pertain to the genetic groups in the Arabian peninsula. Organic acidemias which primarily manifest with neurologic signs, such as 4-hydroxybutyric aciduria, infantile onset 3-methylglutaconic aciduria, and glutaric aciduria type 1 never showed hypoglycemia. Patients with beta-ketothiolase deficiency, biotinidase deficiency, or intermittent or intermediate MSUD, also did not have hypoglycemia during metabolic crisis. Hypoglycemia was rare and mild among neonates with classic MSUD, ethylmalonic aciduria, and isovaleric acidemia. Less than 50% of the patients with MSUD older than 8 months, pyruvate carboxylase deficiency, methylmalonic acidemia, or propionic acidemia had hypoglycemia during metabolic crisis. On the other hand, patients with 3-hydroxy-3-methyl glutaryl-CoA lyase deficiency, holocarboxylase synthetase deficiency, medium or long-chain acyl-CoA dehydrogenase deficiency, neonatal onset 3-methylglutaconic aciduria, glutaric aciduria type 2, and disorders of fructose metabolism invariably had moderate-to-severe hypoglycemia associated with metabolic crisis. The purpose of this report is to provide the pediatrician, particularly in the Middle East, with a diagnostic guideline to the identification and management of different types of organic acidemias, based on co-existing hypoglycemia.
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PMID:Comparative frequency and severity of hypoglycemia in selected organic acidemias, branched chain amino acidemia, and disorders of fructose metabolism. 772 85

We present a new case of holocarboxylase synthetase (HCS) deficiency, a rare autosomal recessive metabolic disorder, causing the "early-onset" form of multiple carboxylase deficiency. The patient was born at term of healthy consanguineous parents after an uncomplicated pregnancy. On the 2nd day of life she refused oral feeding, became tachydyspnoeic and showed excessive weight loss. Laboratory studies showed metabolic acidosis, marked lactic acidaemia, hyperammonaemia and increased urinary excretion of 3-hydroxyisovaleric acid, 3-methylcrotonylglycine, 3-hydroxpropionic acid and methylcitric acid. Peritoneal dialysis combined with oral supplementation of biotin (10 mg/day) started on the 3rd day of life resulted in rapid clinical recovery and normalisation of biochemical parameters. HCS deficiency was established in lymphocytes and skin fibroblasts. The activities of all biotin-dependent carboxylases were severely decreased in fibroblasts grown in medium with moderate biotin concentration (10(-8) mol/l) but normal in a high biotin medium (10(-5) mol/l). Mitochondrial carboxylase activities in lymphocytes were 23%-29% of mean normal during therapy with 20 mg of biotin/day, with the higher dose of 40 mg/day they were within (3-methylcrotoryl-CoA carboxylase, pyruvate carboxylase) or slightly below (propionyl-CoA carboxylase) the normal range. At the age of 3 years the patient's physical and psychomotor development are normal. Early biotin supplementation should be considered in newborns with lactic acidosis and organoaciduria until a final diagnosis has been established. Furthermore, the required individual dose of biotin has to be carefully evaluated biochemically for the individual patient.
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PMID:Holocarboxylase synthetase deficiency: early diagnosis and management of a new case. 831 16

Holocarboxylase synthetase is one of two enzymes known to be involved in the metabolism of biotin. It catalyses the fixation of biotin to inactive apocarboxylases yielding active carboxylases. Deficiency of this enzyme leads to multiple carboxylase deficiency which is fatal in the absence of prompt diagnosis and treatment with biotin. In a pregnancy at risk for deficiency of holocarboxylase synthetase prenatal diagnosis was performed by assay of the enzyme in amniocytes. The Km for biotin was 62.8 nM which was 12 times the control value of 5.0 nM. The Vmax was 2 per cent of the control value. This was confirmed by assay of the activity of propionyl CoA carboxylase (20-26 per cent control), 3-methylcrotonyl CoA carboxylase (14-19 per cent control) and pyruvate carboxylase (12-30 per cent control) and demonstration of biotin responsiveness in vitro. All carboxylase activities were restored to 51-58 per cent of control when amniocytes were cultured in medium containing 1 microM biotin. Diagnosis was ultimately confirmed by assay of holocarboxylase synthetase in lymphocytes from the infant after birth. The Km for biotin of the holocarboxylase synthetase of the infant was 60.3 nM while that of a parallel control was 6.9 nM. Prenatal treatment of the mother with biotin led to a concentration of biotin of 240 nM in the serum of the infant at birth that was four times the Km of the enzyme for biotin. The infant was clinically well at birth, and organic acid analysis of the blood and urine revealed no accumulation of the characteristic metabolites.
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PMID:Prenatal diagnosis and treatment of holocarboxylase synthetase deficiency. 1021 65

The evolution of pyruvate carboxylase has been studied in rat liver and kidney during perinatal development. The pyruvate carboxylase activity, amount of enzyme and mRNA levels have been assayed from 2 days before delivery to weaning. In liver, there is a peak of activity and amount of enzyme 24 h before delivery and 2 peaks, at 12 h and 6 days, after parturition. The transcription of the enzyme gene followed a similar pattern, with mRNA peaks preceding those of activity and amount of enzyme. However, in kidney, pyruvate carboxylase activity, amount and mRNA remain low until weaning. These results confirm the limited role of renal gluconeogenesis during the perinatal development. Since all carboxylases contain biotin as prosthetic group, the biotinylation of pyruvate carboxylase during the perinatal period was investigated by western-blot using streptavidin-biotin peroxidase. In the mitochondrial samples from liver and kidney, all the pyruvate carboxylase detected was fully biotinylated, indicating an early development of the holocarboxylase synthetase activity in the perinatal period. This Western-blot technique also allowed us the detection of other biotin-enzymes based on their molecular weight. In liver, during the perinatal development propionyl-coA and 3-methyl-crotonyl-coA carboxylases followed a pattern of induction similar to pyruvate carboxylase. In kidney, the expression of mitochondrial carboxylases was lower compared to liver and propionyl-coA carboxylase was not detected during the studied period.
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PMID:Evolution of pyruvate carboxylase and other biotin containing enzymes in developing rat liver and kidney. 1056 90


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