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:4.1.2.13 (aldolase)
3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bovine liver 2-oxo-4-hydroxyglutarate aldolase (suggested name: 2-oxo-4-hydroxyglutarate glyoxylate-lyase catalyzing the reaction: 2-oxo-4-hydroxyglutarate in equilibrium pyruvate + glyoxylate) contains eight to ten sulfhydryl groups as determined by titration of the enzyme with either 5,5'-dithiobis(2-nitrobenzoic acid) (Nbs2) or p-mercuribenzoate in the presence of 1% sodium dodecyl sulfate. In the absence of a denaturant, all of the cysteinyl residues react with p-mercuribenzoate whereas only four are accessible to titration with Nbs2. No differences in -SH group reactivity can be detected during titration of the aldolase with p-mercuribenzoate. In contrast, two classes of sulfhydryls can be differentiated in the disulfide exchange reaction with Nbs2 in the absence of a denaturant; one -SH group (Class I) reacts rapidly whereas three additional thiols (Class II) titrate at approx. 0.1 the rate of the Class I-SH residue. Both pyruvate and glyoxylate protect one of the three -SH residues in Class II from reaction with Nbs2. Either substrate also prevents titration of one to two thiol groups by p-mercuribenzoate and decreases the rate of reaction of aldolase -SH groups with Nbs2 in 8 M urea. These ligand-induced changes in -SH reactivity provide a sensitive indication that the enzyme exists in an altered conformational state in the presence of either of its cosubstrates. Titration of the enzyme with either Nbs2 or p-mercuribenzoate results in a progressive loss of aldolase activity which is not proportional to the number of -SH groups modified. The enzyme retains 50% of the activity of the native enzyme when Class I and Class II thiols (i.e. four -SH groups total) are modified with Nbs2; 15% residual activity is still observed following titration of all of the cysteinyl residues with p-mercuribenzoate. Pyruvate and glyoxylate provide partial protection against inactivation. It is concluded that inactivation of 2-oxo-4-hydroxyglutarate aldolase by Nbs2 or p-mercuribenzoate is a consequence of alterations in protein structure which accompany modification of -SH groups. The data argue against the direct participation of an active-site thiol group in the catalytic mechanism of 2-oxo-4-hydroxyglutarate aldolase, be that aldol cleavage and condensation or beta-decarboxylation.
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PMID:Sulfhydryl groups in relation to the structure and catalytic activity of 2-oxo-4-hydroxyglutarate aldolase from bovine liver. 55 45

Treatment with the polyene antibiotic, filipin, renders the spermatozoan cell membrane permeable to small molecules, but not to the intracellular enzymes aldolase and lactate dehydrogenase. Pyruvate (10 mM) as the sole substrate was metabolized very slowly. L-Carnitine increased pyruvate metabolism 3- to 4-fold and allowed limited rates of oxidative phosphorylation. When spermatozoa treated with filipin were supplemented with malate, there was a rapid, almost linear rate of pyruvate metabolism which was slightly increased by L-carnitine. In the absence of malate, 20 to 30% of the pyruvate used was reduced to lactate; this increased to 57% in the presence of malate. Without malate, about 90% of the pyruvate metabolized was converted to lactate and acetate or L-acetylcarnitine. Rutamycin or rotenone increased both the rate of pyruvate use and the delta lactate/deltapyruvate ratio. Under all treatments, L-carnitine consistently reduced the percentage of pyruvate converted to lactate by about 10%; part of the pyruvate was preferentially shunted into L-acetylcarnitine rather than lactate. The mitochondrial inhibitors, rotenone or rutamycin, did not change the amount of pyruvate that was converted to metabolites other than lactate, or L-acetylcarnitine, or both. Pyruvate-supported State 3 respiration was linear only if L-carnitine, or malate, or both, were added to the incubation medium. Added malate was necessary to produce a rapid State 3 respiratory rate and was also required for significant respiratory activity in the presence of rotenone or rutamycin. From cells metabolizing [2-14C]pyruvate (1.4 mM), 14C-labeled acid-extractable metabolites were separated by ion exchange column chromatography. All of the [2-14C]pyruvate (+/-5%) used was recovered in 14C-labeled metabolites and 14CO2. In the presence of malate, citrate accumulation was significant, and was always large in comparison to flux through the citric acid cycle. Glutamate, beta-hydroxybutyrate, acetoacetate, fumarate, aspartate, and alpha-ketoglutarate did not accumulate in significant amounts. Some 14C-labeled succinate was produced but only in the presence of malate. Alkaline hydrolysis of a fraction containing carnitine esters yielded acetate and a compound tentatively identified as beta-hydroxybutyrate or lactate. As in intact cells, intramitochondrial lactate dehydrogenase competes successfully with the electron transport system for the NADH generated by pyruvate metabolism. The role of lactate and L-carnitine, and conclusions suggested by the accumulation of certain metabolites are discussed in relation to control of citric acid cycle activity.
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PMID:Mitochondrial metabolism of pyruvate in bovine spermatozoa. 83 19

Interactions of glucose-6-phosphate isomerase (D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9), aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate lyase, EC 4.1.2.13), glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12), triose-phosphate isomerase (D-glyceraldehyde-3-phosphate ketol-isomerase, EC 5.3.1.1), phosphoglycerate mutase (D-phosphoglycerate 2,3-phosphomutase, EC 5.4.2.1), phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.3), enolase (2-phospho-D-glycerate hydro-lyase, EC 4.2.1.11), pyruvate kinase (ATP:Pyruvate O2-phosphotransferase, EC 2.7.1.40) and lactate dehydrogenase [S)-lactate:NAD+ oxidoreductase, EC 1.1.1.27) with F-actin, among the glycolytic enzymes listed above, and with phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) were studied in the presence of poly(ethylene glycol). Both purified rabbit muscle enzymes and rabbit muscle myogen, a high-speed supernatant fraction containing the glycolytic enzymes, were used to study enzyme-F-actin interactions. Following ultracentrifugation, F-actin and poly(ethylene glycol) tended to increase and KCl to decrease the pelleting of enzymes. In general, the greater part of the pelleting occurred in the presence of both F-actin and poly(ethylene glycol) and the absence of KCl. Enzymes that pelleted more in myogen preparations than as individual purified enzymes in the presence of poly(ethylene glycol) and the absence of F-actin were tested for specific enzyme-enzyme associations, several of which were observed. Such interactions support the view that the internal cell structure is composed of proteins that interact with one another to form the microtrabecular lattice.
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PMID:Heteromerous interactions among glycolytic enzymes and of glycolytic enzymes with F-actin: effects of poly(ethylene glycol). 333 56

Round spermatids were prepared from rat testes and incubated with various substrates (glucose, fructose, pyruvate, lactate and acetate) to measure utilization of substrates and production of ATP in the presence of saturating levels of each substrate. By both criteria lactate is the preferred substrate by a factor of 3 or 4. Production of more than half of the ATP with lactate is substrate is prevented by addition of an inhibitor of alpha-ketoacid dehydrogenase (5-methoxyindole-2-carboxylic acid) Pyruvate and lactate are interconverted and pyruvate inhibits production of ATP from lactate. Synthesis of ATP with lactate and with pyruvate is inhibited by rotenone, rutamycin or 2,4-dinitrophenol. Utilization of glucose is limited by aldolase activity. These findings suggest that exogenous lactate is oxidized by lactate dehydrogenase followed by pyruvate dehydrogenase and Krebs; cycle enzymes under conditions which do not allow pyruvate to inhibit lactate dehydrogenase. ATP is synthesized through electron transport. Post-mitochondrial supernate from spermatids showed that high concentration of pyruvate (greater than 1 mM) inhibit lactate dehydrogenase with pyruvate as substrate and that with lactate as substrate, pyruvate behaves as a competitive inhibitor of lactate dehydrogenase. Evidently lactate is the preferred substrate for round spermatids and energy production is most efficient when this substance is present in high concentrations and pyruvate is present in low concentrations. Reasons are given for suggesting that Sertoli cells may provide the relatively large amounts of lactate required by round spermatids.
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PMID:Metabolism of round spermatids from rats: lactate as the preferred substrate. 708 19

1. With fumarate as the terminal electron acceptor and either H2 or formate as donor, Vibrio succinogenes could grow anaerobically in a mineral medium using fumarate as the sole carbon source. Both the growth rate and the cell yield were increased when glutamate was also present in the medium. 2. Glutamate was incorporated only into the amino acids of the glutamate family (glutamate, glutamine, proline and arginine) of the protein. The residual cell constituents were synthesized from fumarate. 3. Pyruvate and phosphoenolpyruvate, as the central intermediates of most of the cell constituents, were formed through the action of malic enzyme and phosphoenolpyruvate synthetase. Fructose-1,6-bisphosphate aldolase was present in the bacterium suggesting that this enzyme is involved in carbohydrate synthesis. 4. In the absence of added glutamate the amino acids of the glutamate family were synthesized from fumarate via citrate. The enzymes involved in glutamate synthesis were present. 5. During growth in the presence of glutamate, net reducing equivalents were needed for cell synthesis. Glutamate and not H2 or formate was used as the source of these reducing equivalents. For this purpose part of the glutamate was oxidized to yield succinate and CO2. 6. The alpha-ketoglutarate dehydrogenase involved in this reaction was found to use ferredoxin as the electron acceptor. The ferredoxin of the bacterium was reoxidized by means of a NADP-ferredoxin oxidoreductase. Enzymes catalyzing the reduction of NAD, NADP or ferredoxin by H2 or formate were not detected in the bacterium.
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PMID:Biosynthetic Pathways of Vibrio succinogenes growing with fumarate as terminal electron acceptor and sole carbon source. 710 60

Two enzymes have been found to be involved in bacterial N-acetyl-D-neuraminic acid (NeuAc) synthesis: NeuAc synthase, which condenses N-acetyl-L,D-mannosamine and phosphoenolpyruvate, and NeuAc lyase or NeuAc aldolase, which condenses N-acetyl-D-mannosamine and pyruvate. When we used Escherichia coli K1 crude extracts, we observed the generation of NeuAc in the presence of N-acetylmannosamine and both phosphoenolpyruvate (NeuAc synthase activity) or pyruvate (NeuAc lyase activity). However, when crude extracts were fractionated by Sephacryl S-200 chromatography, NeuAc synthase activity disappeared. A chromatographic peak of NeuAc synthase activity was detected when column fractions were re-tested in the presence of the active NeuAc lyase peak. Furthermore, crude extracts converted phosphoenolpyruvate into pyruvate. Pyruvate depletion, due to the addition of pyruvate decarboxylase to the NeuAc synthase reaction mixture, blocked NeuAc formation. Moreover, after NeuAc lyase immunoprecipitation no NeuAc synthase was detected. These findings suggest that NeuAc synthase is not present in E. coli K1 and therefore that NeuAc lyase is the only enzyme responsible for NeuAc synthesis in this bacterium.
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PMID:N-acetyl-D-neuraminic acid synthesis in Escherichia coli K1 occurs through condensation of N-acetyl-D-mannosamine and pyruvate. 777 33

Several new enzymes of utility in the synthesis of carbohydrates have been reported during the past year. Additionally, the utility of several well studied enzymes has been expanded. Pyruvate aldolases, aldolase abzymes and both wild-type and mutated glycosidases have found increasing acceptance in the community. Preliminary reports suggest that thermophilic enzymes may possess significant advantages compared to their mesophilic counterparts for carbohydrate synthesis.
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PMID:Enzyme-catalyzed synthesis of carbohydrates. 1067 69

The hyperthermophilic, sulfate-reducing archaeon Archaeoglobus fulgidus strain 7324, rather than the type strain VC16, was found to grow on starch and sulfate as energy and carbon source. Fermentation products and enzyme activities were determined in starch-grown cells and compared to those of cells grown on lactate and sulfate. During exponential growth on starch, 1 mol of glucose-equivalent was incompletely oxidized with sulfate to approximately 2 mol acetate, 2 mol CO2 and 1 mol H2S. Starch-grown cells did not contain measurable amounts of the deazaflavin factor F420 (<0.03 nmol/mg protein) and thus did not show the F420-specific green-blue fluorescence. In contrast, lactate (1 mol) was completely oxidized with sulfate to 3 mol CO2 by strain 7324, and lactate-grown cells contained high amounts of F420 (0.6 nmol/mg protein). In extracts of starch-grown cells, the following enzymes of a modified Embden-Meyerhof pathway were detected: ADP-dependent hexokinase (ADP-HK), phosphoglucose isomerase, ADP-dependent 6-phosphofructokinase (ADP-PFK), fructose-1,6-phosphate aldolase, glyceraldehyde-3-phosphate:ferredoxin oxidoreductase (GAP:FdOR), phosphoglycerate mutase, enolase, and pyruvate kinase (PK). Specific activities of ADP-HK, ADP-PFK, GAP:FdOR, and PK were significantly higher in starch-grown cells than in lactate-grown cells, indicating induction of these enzymes during starch catabolism. Pyruvate conversion to acetate involved pyruvate:ferredoxin oxidoreductase and ADP-forming acetyl-CoA synthetase. The findings indicate that the archaeal sulfate reducer A. fulgidus strain 7324 converts starch to acetate via a modified Embden-Meyerhof pathway and acetyl-CoA synthetase (ADP-forming). This is the first report of growth of a sulfate reducer on starch, i.e. on a polymeric sugar.
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PMID:Sugar utilization in the hyperthermophilic, sulfate-reducing archaeon Archaeoglobus fulgidus strain 7324: starch degradation to acetate and CO2 via a modified Embden-Meyerhof pathway and acetyl-CoA synthetase (ADP-forming). 1170 74

Ignicoccus hospitalis is an autotrophic hyperthermophilic archaeon that serves as a host for another parasitic/symbiotic archaeon, Nanoarchaeum equitans. In this study, the biosynthetic pathways of I. hospitalis were investigated by in vitro enzymatic analyses, in vivo (13)C-labeling experiments, and genomic analyses. Our results suggest the operation of a so far unknown pathway of autotrophic CO(2) fixation that starts from acetyl-coenzyme A (CoA). The cyclic regeneration of acetyl-CoA, the primary CO(2) acceptor molecule, has not been clarified yet. In essence, acetyl-CoA is converted into pyruvate via reductive carboxylation by pyruvate-ferredoxin oxidoreductase. Pyruvate-water dikinase converts pyruvate into phosphoenolpyruvate (PEP), which is carboxylated to oxaloacetate by PEP carboxylase. An incomplete citric acid cycle is operating: citrate is synthesized from oxaloacetate and acetyl-CoA by a (re)-specific citrate synthase, whereas a 2-oxoglutarate-oxidizing enzyme is lacking. Further investigations revealed that several special biosynthetic pathways that have recently been described for various archaea are operating. Isoleucine is synthesized via the uncommon citramalate pathway and lysine via the alpha-aminoadipate pathway. Gluconeogenesis is achieved via a reverse Embden-Meyerhof pathway using a novel type of fructose 1,6-bisphosphate aldolase. Pentosephosphates are formed from hexosephosphates via the suggested ribulose-monophosphate pathway, whereby formaldehyde is released from C-1 of hexose. The organism may not contain any sugar-metabolizing pathway. This comprehensive analysis of the central carbon metabolism of I. hospitalis revealed further evidence for the unexpected and unexplored diversity of metabolic pathways within the (hyperthermophilic) archaea.
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PMID:Insights into the autotrophic CO2 fixation pathway of the archaeon Ignicoccus hospitalis: comprehensive analysis of the central carbon metabolism. 1740 Jul 48

Conversion of glucose to pyruvate via reactions homologous to the non-phosphorylated Entner-Doudoroff (non-P ED) pathway could be achieved in the presence of two amino acid catalysts, cysteine and histidine: cystine oxidizes glucose to gluconic acid by the reaction homologous to glucose dehydrogenase and histidine changes gluconic acid to 2-keto-3-deoxy gluconic acid, then to pyruvate by the reaction homologous to gluconic acid dehydratase and 2-keto-3-deoxy gluconate aldolase, respectively. Pyruvate can be converted to acetyl CoA by the reaction with CoA, TPP and FAD in the presence of cysteine and histidine, which resembles pyruvate dehydrogenase reaction. It was found that gluconic acid dehydration alone is non-specific, in contrast to other reactions. The non-P ED pathway is used by some extreme thermophiles in bacteria and archaea, usually thought as the oldest among the contemporary organisms. This study suggests the possible contribution of amino acid to the origin of the glycolytic pathway.
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PMID:Prebiotic origin of glycolytic metabolism: histidine and cysteine can produce acetyl CoA from glucose via reactions homologous to non-phosphorylated Entner-Doudoroff pathway. 1851 57


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