Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.4.1.1 (pyruvate carboxylase)
 1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzymes of carbon dioxide heterotrophic fixation were studied in six strains of coryneform bacteria belonging to the genera Arthrobacter, Brevibacterium, Corynebacterium and Nocardia. All of the strains were found to contain PEP (phosphoenolpyruvate) carboxylase (EC 4.1.1.31), NADP or NAD dependent malic enzymes (EC 1.1.1.38--40). Pyruvate carboxylase (EC 6.4.1.1) was found only in three strains of coryneforms: Brevibacterium ammoniagenes, Corynebacterium aquaticum and Nocardia erythropolis. PEP carboxykinase (EC 4.1.1.32) was detected in Brevibacterium ammoniagenes and Nocardia erythropolis. PEP carboxytransphosphorylase (EC 4.1.1.38) was found only in Brevibacterium ammoniagenes. These data suggest that carboxylation of C3-acids is one of the essential pathways in some coryneforms supplying the citric acid cycle with the products of glycolysis. The composition and the level of carboxylation enzymes reflect the ecological characteristics of the organisms rather than their taxonomical relations.
 ...
PMID:[Carboxylation enzymes of coryneform bacteria]. 11 47

A high molecular weight fraction was obtained by extended dialysis of urine of healthy and uremic subjects. After addition to the incubation medium, this fraction inhibited gluconeogenesis by rat kidney cortex slices. From the six subfractions extracted by gel chromatography (Sephadex G 100) fraction IV caused a decrease of glucose formation. The activity of PEP-carboxykinase but not of pyruvate carboxylase was reduced, indicating a decreased formation of phosphoenol pyruvate. The total high molecular weight fraction stimulated glucose release by liver slices from fed but not from starved rats. In the absence of amino acids, urea formation was not stimulated. The activity of pyruvate carboxylase was reduced in both groups, PEP-carboxykinase activity was, however, only reduced in the starved group. The addition of uremic serum caused increased glucose release. Inhibition of PEP-carboxykinase activity by quinolinic acid (15 mM) resulted in inhibition of glucose formation by 35% in the uremic group and 54% in the control group in livers of 24 hr starved rats. Thus in uremia there may be incorporation of serine carbon skeletons into glucose via hydroxypyruvate, not via pyruvate. Chromatography on calibrated columns indicated that about 40% of the urinary fractions had molecular weights in the upper range of the "middle molecules" category. The positive correlation between toxicity and the total amount of high molecular weight substances excreted do not confirm the hypothesis of augmented retention of "toxins" in uremic patients. It must be appreciated that these results refer only to the undialyzable fraction of urine which contains only 0.5% by weight of the total urine solids.
 ...
PMID:Effect of urine metabolites from healthy and uremic subjects on gluconeogenesis in slices of rat kidney cortex and liver. 99 68

Phosphoenol pyruvate carboxylase, or PEP-c (EC 4.1.1.31), was shown to be the only enzyme catalyzing anaplerotic synthesis of oxalacetic acid in Brevibacterium flavum synthesizing lysine. Acetyl-CoA is required for the operation of PEP-c in the strains. Changes in the activity of PEP-c did not entirely correlate with those of the citric acid cycle enzymes. Hence, PEP-c is involved not only in the citric acid cycle, but also in other functions of the cell. A correlation has been found between changes in the activity of PEP-c, the enzymes of the citric acid cycle and lysine production in B. flavum.
 ...
PMID:[Functional characteristics of phosphoenolpyruvate carboxylase in bacteria producing lysine]. 680 9

Evidence is presented in support of a pathway in skeletal muscle of glyconeogenesis (glycogen biosynthesis de novo) from L-glutamate and related amino acids involving the enzyme phosphoenolpyruvate carboxykinase (PEP CK). In the rat hemidiaphragm in vitro, not only did L-[U]-14C]glutamate exert a glycogen-sparing action, but 14C-label was incorporated into glycogen. The incorporation is thought not to be simply via label randomization and was decreased by factors that increased glycolysis or pyruvate oxidation. 3-Mercaptopicolinate and amino-oxyacetate, specific inhibitors of PEP CK and aminotransferase-type enzymes, respectively, decreased 14C-incorporation from L-[U-14C]glutamate into glycogen. No quantitative determination of apparent glyconeogenic flux was made, and it remains to be established whether glyconeogenesis via PEP CK and/or via PEP CK coupled with "malic' enzyme (or pyruvate carboxylase) is functionally important in skeletal muscle.
 ...
PMID:A putative pathway of glyconeogenesis in skeletal muscle. 729 90

New cytochemical method, based on biochemical experiments, was elaborated for the ultrastructural localization of phospho(enol)pyruvate carboxylase (EC 4.1.1.31). The procedure was used to study the saprophytic submerged mycelium of the ascomycetous fungus Claviceps purpurea Tul. producing clavine alkaloids. The pelleted mycelium was fixed in ice cold 3% glutaraldehyde in 50 mM cacodylate buffer pH 7.2 and washed repeatedly in the same cold buffer The reaction mixture contained 100 mM Tris-HCl buffer pH 9.0, 10 mM phospho(enol)pyruvate, 30 mM sodium potassium tartrate, 3 mM Pb(NO3)2, 60 mM MgCl2 and 30 mM NaHCO3. Enzyme activity was localized in vacuoles, particularly inside lipid globules (spherosomes) and less frequently in membranous vesicles. Acetyl-CoA activated PEP-carboxylase both in cell free extracts and in the cytochemical staining. Aspartate inhibited the enzyme in the biochemical assay with coupled malate dehydrogenase system; the cytochemical reaction was not influenced, probably due to the interference of asparagine synthase (EC 6.3.1.1).
 ...
PMID:Electron-cytochemical localization of phospho(enol)pyruvate carboxylase (EC 4.1.1.31) in fungal cells. 739 80

Despite the marked changes that crustacean muscle undergoes during the molt cycle, pyruvate kinase is present as the same form throughout the molt cycle. This pyruvate kinase was subject to feed-forward activation by fructose-1, 6 bisphosphate (FBP) as well as feed-back inhibition by MgATP. The enzyme showed a high affinity for phosphoenolpyruvate (Km = 0.1 mM) but showed no cooperativity in substrate binding. The addition of 0.05 mM FBP reduced the PEP Km to 0.05 mM. MgATP inhibition showed a Ki of 1.8 mM versus PEP. The inhibition due to MgATP could be reversed by FBP. Various other compounds inhibited the enzyme, including citrate, alpha-ketoglutarate, tryptophan, and malate, although at rather high levels. Measurements of the reversal of this pyruvate kinase, taken together with the low levels of phosphoenolpyruvate carboxykinase and pyruvate carboxylase, predict only minimal levels of gluconeogenic flux in crustacean muscle.
 ...
PMID:Catalytic and regulatory properties of muscle pyruvate kinase from Cancer magister. 746 68

Incubation of the nonphosphorylated form of maize-leaf phospho enol pyruvate carboxylase (orthophosphate: oxaloacetate carboxy-lyase (phosphorylating), PEPC, EC 4.1.1.31) with the reagent pyridoxal 5'-phosphate (PLP) resulted in time-dependent, reversible inactivation and desensitization to the activator glucose 6-phosphate (Glc6P) and other related phosphorylated compounds. Both processes are not connected, since (i) when the PLP-modification was carried out in the presence of saturating ligands of the active site, which prevents inactivation, the desensitization to Glc6P is still observed, and (ii) under some experimental conditions the desensitization reaction is 4-times faster than the inactivation. Desensitization to Glc6P is first order with respect to PLP and has a second-order forward rate constant of 4.7 +/- 0.3 s-1 M-1 and a first-order reverse rate constant of 0.0046 +/- 0.0002 s-1. Correlation studies between the remaining Glc6P sensitivity and mol of PLP residues incorporated per mol of enzyme subunit indicate that one lysyl group for enzyme monomer is involved in the sensitivity of the enzyme to Glc6P. The reactivity of this group is increased by polyethylene glycol and glycerol, while the reactivity of the lysyl group of the active site is not affected by these organic cosolutes. In the presence but not in the absence of the organic cosolutes, Glc6P by itself offers significant protection against desensitization, while increases the extent of inactivation. Free PEP or PEP-Mg have opposite effects, protecting the enzyme against inactivation and increasing the degree of desensitization. They also increases the protection against desensitization afforded by Glc6P. Finally, the PEPC inhibitor malate provides some protection against both inactivation and desensitization. Taken together, these results are consistent with PLP-modification of a highly reactive lysyl group at or near the allosteric Glc6P-site.
 ...
PMID:Desensitization to glucose 6-phosphate of phosphoenolpyruvate carboxylase from maize leaves by pyridoxal 5'-phosphate. 904 97

1-Methyl-4-phenylpyridinium (MPP+) is a mitochondrial Complex I inhibitor and is frequently used to investigate the pathological degeneration of neurons associated with Parkinson's disease (PD). In vitro, extracellular concentration of glucose is one of the most critical factors in establishing the vulnerability of neurons to MPP+ toxicity. While glucose is the primary energy fuel for the brain, central nervous system (CNS) neurons can also take up and utilize other metabolic intermediates for energy. In this study, we compared various monosaccharides, disaccharides, nutritive/non-nutritive sugar alcohols, glycolytic and gluconeogenic metabolic intermediates for their cytoprotection against MPP+ in murine brain neuroblastoma cells. Several monosaccharides were effective against MMP+ (500 microM) including glucose, fructose and mannose, which restored cell viability to 109 +/- 5%, 70 +/- 5%, 99 +/- 3% of live controls, respectively. Slight protective effects were observed in the presence of 3-phosphoglyceric acid and glucose-6-phosphate; however, no protective effects were exhibited by galactose, sucrose, sorbitol, mannitol, glycerol or various gluconeogenic and ketogenic amino acids. On the other hand, fructose 1,6 bisphosphate and gluconeogenic energy intermediates [pyruvic acid, malic acid and phospho(enol)pyruvate (PEP)] were neuroprotective against MPP+. The gluconeogenic intermediates elevated intracellular levels of ATP and reduced propidium iodide (PI) nucleic acid staining to live controls, but did not alter the MPP(+)-induced loss of mitochondrial O2 consumption. These data indicate that malic acid, pyruvic acid and PEP contribute to anaerobic substrate level phosphorylation. The use of hydrazine sulfate to impede gluconeogenesis through PEP carboxykinase (PEPCK) inhibition heightened the protective effects of energy substrates possibly due to attenuated ATP demands from pyruvate carboxylase (PC) activity and pyruvate mitochondrial transport. It was concluded from these studies that several metabolic intermediates are effective in fueling anaerobic glycolysis during mitochondrial inhibition by MPP+.
 ...
PMID:The role of glycolysis and gluconeogenesis in the cytoprotection of neuroblastoma cells against 1-methyl 4-phenylpyridinium ion toxicity. 1256 89

Using our recently developed sensor reactor approach, lysine-producing, nongrowing Corynebacterium glutamicum MH20-22B cells were subjected to serial (13)C-labeling experiments for flux analysis during the leucine-limited fed-batch production phase in a 300-L bioreactor. Based on two-dimensional (2D) nuclear magnetic resonance (NMR) measurements of (13)C-labeling patterns of cytoplasmic free metabolites, metabolic flux distributions in the central metabolism were successfully determined. Focusing on the highly concentrated metabolite L-glutamate, the working hypothesis was validated that the equilibration of labeling patterns in intracellular pools was much faster (up to 9.45 min) than the labeling period (3 h) used in the experiments. Analysis of anaplerotic reactions revealed that highly selective lysine production was accompanied by a significant reduction of decarboxylating reactions from 10 mol% to only 2 mol%, whereas PEP/pyruvate-carboxylating fluxes remained constant at about 40 mol% of consumed glucose. These results support the conclusion that an optimized C. glutamicum L-lysine producer should possess increased PEP carboxylase and/or pyruvate carboxylase activity combined with downregulated, decarboxylating fluxes consuming oxaloacetate/malate. The findings also illustrate the usefulness of the sensor reactor approach in the study of industrial fermentations.
 ...
PMID:Serial flux mapping of Corynebacterium glutamicum during fed-batch L-lysine production using the sensor reactor approach. 1476 Jun 90

An adhE, ldhA double mutant Escherichia coli strain, SBS110MG, has been constructed to produce succinic acid in the presence of heterologous pyruvate carboxylase (PYC). The strategic design aims at diverting maximum quantities of NADH for succinate synthesis by inactivation of NADH competing pathways to increase succinate yield and productivity. Additionally an operational PFL enzyme allows formation of acetyl-CoA for biosynthesis and formate as a potential source of reducing equivalents. Furthermore, PYC diverts pyruvate toward OAA to favor succinate generation. SBS110MG harboring plasmid pHL413, which encodes the heterologous pyruvate carboxylase from Lactococcus lactis, produced 15.6 g/L (132 mM) of succinate from 18.7 g/L (104 mM) of glucose after 24 h of culture in an atmosphere of CO(2) yielding 1.3 mol of succinate per mole of glucose. This molar yield exceeded the maximum theoretical yield of succinate that can be achieved from glucose (1 mol/mol) under anaerobic conditions in terms of NADH balance. The current work further explores the importance of the presence of formate as a source of reducing equivalents in SBS110MG(pHL413). Inactivation of the native formate dehydrogenase pathway (FDH) in this strain significantly reduced succinate yield, suggesting that reducing power was lost in the form of formate. Additionally we investigated the effect of ptsG inactivation in SBS110MG(pHL413) to evaluate the possibility of a further increase in succinate yield. Elimination of the ptsG system increased the succinate yield to 1.4 mol/mol at the expense of a reduction in glucose consumption of 33%. In the presence of PYC and an efficient conversion of glucose to products, the ptsG mutation is not indispensable since PEP converted to pyruvate as a result of glucose phosphorylation by the glucose specific PTS permease EIICB(glu) can be rediverted toward OAA favoring succinate production.
 ...
PMID:Efficient succinic acid production from glucose through overexpression of pyruvate carboxylase in an Escherichia coli alcohol dehydrogenase and lactate dehydrogenase mutant. 1580 71


1 2 Next >>