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)

The simultaneous effect of calmodulin and aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13) on the concentration-dependent behaviour of muscle phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) has been analysed by means of a covalently attached fluorescent probe, gel penetration experiments, and using a kinetic approach. We found that calmodulin-induced inactivation of phosphofructokinase is suspended by addition of an equimolar amount of aldolase. This effect was attributed to an apparent competition of calmodulin and aldolase for the dimeric forms of kinase. Moreover, the direct binding of aldolase to calmodulin has also been demonstrated, which resulted in a significant decrease in the kcat value of the enzyme. The quantitative analysis of these interactions in the system phosphofructokinase-calmodulin-aldolase is presented. A possible molecular model for the modulation of phosphofructokinase action by macromolecular interactions is envisaged.
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PMID:Modulation of phosphofructokinase action by macromolecular interactions. Quantitative analysis of the phosphofructokinase-aldolase-calmodulin system. 297 56

Low concentrations of sulfite or nitrite (about 0.5 mmol) when applied at pH 3.6, caused a rapid and drastic decrease of the concentration of ATP in yeast cells. Under these conditions, alcoholic fermentation was inhibited by sulfite and to a lesser extent by nitrite. Ethanol consumption under aerobic conditions was shown to be more sensitive to nitrite than to sulfite. This indicates a higher sensitivity of respiratory processes to nitrite than to sulfite. Among 15 enzyme activities assayed in extracts from yeast cells after incubation with sulfite or nitrite, glyceraldehyde-3-phosphate dehydrogenase was shown to be the most sensitive. Analysis of the steady-state concentrations of intermediates of alcoholic fermentation in intact yeast cells also implies inhibition by sulfite or nitrite of the glyceraldehyde-3-phosphate dehydrogenase step of fermentation. In contrast to nitrite, sulfite had an additional effect by accumulating the intracellular steady state concentration of glyceraldehyde-3-phosphate 10 to 100-fold over the concentration in the absence of sulfite. In vitro studies on the equilibrium catalyzed by triosephosphate isomerase or aldolase confirmed the postulated shift of equilibrium concentrations by a formation of complex of glyceraldehyde-3-phosphate with sulfite.
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PMID:Effect of sulfite or nitrite on the ATP content and the carbohydrate metabolism in yeast. 299 53

Phosphoglucose isomerase negative mutant of mucoid Pseudomonas aeruginosa accumulated relatively higher concentration of fructose 1,6-bisphosphate (Fru-1,6-P2) when mannitol induced cells were incubated with this sugar alcohol. Also the toluene-treated cells of fructose 1,6-bisphosphate aldolase negative mutant of this organism produced Fru-1,6-P2 from fructose 6-phosphate in presence of ATP, but not from 6-phosphogluconate. The results together suggested the presence of an ATP-dependent fructose 6-phosphate kinase (EC 2.7.1.11) in mucoid P. aeruginosa.
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PMID:Accumulation of fructose 1,6-bisphosphate in mutant cells of mucoid Pseudomonas aeruginosa as an evidence of phosphofructokinase activity. 301 51

6-Phosphofructo-1-kinase (phosphofructokinase) (ATP:D-fructose-6-P 1-phosphotransferase, EC 2.7.1.11) can be identified in sheep heart homogenates in two forms, a soluble form and a form bound to the particulate fraction. Homogenates from immediately-dissected hearts have the enzyme in the soluble form, while those collected after a delay have the enzyme bound to the particulate fraction. Aldolase appears to show the same change in its location. Homogenization in a solution with concentrated macromolecular species (20% albumin) results in a greater association of phosphofructokinase and of aldolase to the particulate fraction in homogenates from immediately dissected hearts. Phosphofructokinase activity can be solubilized by two specific means: by high ionic strength, which is dependent upon specific salts; or by low ionic strength, which is dependent upon the presence of phosphofructokinase substrates or modifier ligands. These two means of solubilization are affected differently upon decreasing the pH below 6.9: the solubilization at low ionic strength is prevented, whereas phosphofructokinase is still solubilized by high ionic strength. Under the latter condition, the enzyme is in the inactive dimeric state, which can be activated at an alkaline pH. Myofibrils present in the particulate fraction can account for the binding of phosphofructokinase in heart homogenates. Purified myofibrils, when added to heart supernatant fluids, can bind phosphofructokinase at a slightly acidic pH. Conditions for phosphofructokinase binding to myofibrils, as well as its dissociation, follow what was observed with the binding of phosphofructokinase to the particulate fraction. At an acidic pH, and in the presence of a high concentration of ATP, phosphofructokinase exhibits low activity. However, if phosphofructokinase is assayed under these conditions while bound to myofibrils, the enzyme is activated.
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PMID:Heart 6-phosphofructo-1-kinase. Subcellular distribution and binding to myofibrils. 315 84

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

Formation of a bienzyme complex of pig heart mitochondrial malate dehydrogenase and citrate synthase in a buffered system is demonstrated by means of a covalently attached fluorescent probe to citrate synthase. Assuming 1:1 stoichiometry of the enzymes in the complex, an apparent dissociation constant of 10(-6) M was calculated from fluorescence anisotropy measurements. The effect of various metabolites on the interaction was tested. NAD+, oxalacetate, citrate, ATP, and L(-)- or D(+)-malate had no effect on the association of the two enzymes, whereas alpha-ketoglutarate increased and NADH decreased it. The interaction of mitochondrial citrate synthase with cytosolic malate dehydrogenase was found to be much weaker, whereas interaction of citrate synthase with another cytosolic enzyme, aldolase, could not be detected. In kinetic experiments, the activation of malate dehydrogenase by citrate synthase was observed. The effect of pyridine nucleotides and alpha-ketoglutarate is discussed in relation to the direction of the metabolic flow of oxalacetate.
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PMID:Quantitation of the interaction between citrate synthase and malate dehydrogenase. 357 Dec 48

Neurone-specific enolase (NSE) and the brain form of creatine phosphokinase (CPK-BB) were previously found to be present in rat synaptosomal plasma membranes (SPM) using two-dimensional gel (2-D gel) and peptide analysis; enzymatic activities of these and of pyruvate kinase (PK), all involved in ATP generation, were shown to be "cryptic" unless the SPM were treated with Triton X-100. We now show that enzymatic activation also occurs when the SPM are treated with trifluoperazine (TFP). TFP activation occurred even when the enzymes were membrane associated, showing that solubilization was not responsible for "unmasking" the enzyme activities. When TFP treatment was performed at alkaline instead of neutral pH, NSE and CPK-BB were released as well as PK, nonneuronal enolase, and aldolase which were identified by 2-D gel and tryptic peptide analysis. Other proteins released included calmodulin, actin, and the 70-kilodalton heat-shock cognate protein. Tubulin, synapsin I, and a 35-kilodalton basic protein were largely unaffected. The latter was identified as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase on the basis of 2-D gel and peptide analyses and subsequent partial sequencing of a rat brain cDNA coding for the same protein. TFP treatment is thus useful for activating latent enzymes as well as for distinguishing enzymes that have a different disposition on the membrane.
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PMID:Trifluoperazine activates and releases latent ATP-generating enzymes associated with the synaptic plasma membrane. 358 33

Steady-state kinetic measurements have shown that 8-azido-1,N6-ethenoadenosine 5'-triphosphate (8-N3-epsilon ATP) can be noncovalently bound to rabbit muscle fructose 1,6-bisphosphate aldolase with Ki = 0.075 mM at pH 8.5. This binding is purely competitive with substrate and occurs at the strong binding site for mononucleotides. Photoaffinity labeling of aldolase in the presence of 8-azido-1,N6-ethenoadenosine 5'-triphosphate results in inactivation of the enzyme. Aldolase is protected against modification in the presence of the inhibitors hexitol 1,6-bisphosphate or ATP. The labeling is saturable, and a good correlation is observed between the loss of enzymatic activity and the incorporation of 8-N3-epsilon ATP into aldolase. In addition, aldolase loses its ability to bind to phosphocellulose following modification. Digestion of labeled protein with trypsin, chymotrypsin, and cyanogen bromide revealed substantial modification of peptide 259-269. Thr-265 was identified as the residue that was covalently modified by 8-N3-epsilon ATP. On the basis of these results and other data we propose a model for the mononucleotide binding site.
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PMID:Photoaffinity labeling of rabbit muscle fructose-1,6-bisphosphate aldolase with 8-azido-1,N6-ethenoadenosine 5'-triphosphate. 365 92

The effects of D-glyceraldehyde on the hepatocyte contents of various metabolites were examined and compared with the effects of fructose, glycerol and dihydroxyacetone, which all enter the glycolytic/gluconeogenic pathways at the triose phosphate level. D-Glyceraldehyde (10 MM) caused a substantial depletion of hepatocyte ATP, as did equimolar concentrations of fructose and glycerol. D-Glyceraldehyde and fructose each caused a 2-fold increase in fructose 1,6-bisphosphate and the accumulation of millimolar quantities of fructose 1-phosphate in the cells. D-Glyceraldehyde caused an increase in the glycerol 3-phosphate content and a decrease in the dihydroxyacetone phosphate content, whereas dihydroxyacetone increased the content of both metabolites. The increase in the [glycerol 3-phosphate]/[dihydroxyacetone phosphate] ratio caused by D-glyceraldehyde was not accompanied by a change in the cytoplasmic [NAD+]/[NADH] ratio, as indicated by the unchanged [lactate]/[pyruvate] ratio. The accumulation of fructose 1-phosphate from D-glyceraldehyde and dihydroxyacetone phosphate in the hepatocyte can account for the depletion of the intracellular content of the latter. Presumably ATP is depleted as the result of the accumulation of millimolar amounts of a phosphorylated intermediate, as is the case with fructose and glycerol. It is suggested that the accumulation of fructose 1-phosphate during hepatic fructose metabolism is the result of a temporary increase in the D-glyceraldehyde concentration because of the high rate of fructose phosphorylation compared with triokinase activity. The equilibrium constant of aldolase favours the formation and thus the accumulation of fructose 1-phosphate.
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PMID:Metabolic effects of D-glyceraldehyde in isolated hepatocytes. 382 66

Protein synthesis, normally a light-dependent process in isolated mature chloroplasts of Euglena gracilis var. bacillaris will take place in darkness if ATP and Mg2+ (ATP/Mg) are supplied. Either 5 or 10 mM ATP plus 15 mM MgCl2 are optimal and rates equal to those in the light can be obtained. Since ATP and Mg2+ are not stoichiometrically related, and since the optimal Mg2+ concentration is similar to that which stabilizes chloroplast ribosomes in vitro, it is suggested that the chloroplast is freely permeable to Mg2+ under these conditions. Protein synthesis under these conditions is not inhibited appreciably by DCMU, FCCP, cycloheximide, or by the addition of ribonuclease, but is highly sensitive to chloramphenicol. Carbon dioxide fixation is also a light-dependent process in isolated mature chloroplasts from Euglena, but addition of ATP (5 mM) and fructose bisphosphate (5 mM) plus aldolase (1.0 unit/ml) (fructose-1,6-bisphosphate/aldolase) yields CO2 fixation rates in darkness that are 43% of those normally obtained in the light. Mg2+ higher than 1.0 mM (e.g., 16 mM) is somewhat inhibitory. Chlorophyll synthesis from 5-aminolevulinate in 36 h developing chloroplasts from Euglena is also light-dependent, but addition of ATP/Mg and fructose-1,6-bis-phosphate/aldolase in darkness brings about the accumulation of a compound having the same RF on chromatography as protochlorophyllide from Barley; a subsequent brief illumination of the chloroplasts converts this compound to a compound with the RF of chlorophyll. Thus Euglena chloroplasts supplied with appropriate additions can carry out protein synthesis, carbon dioxide fixation and most of chlorophyll synthesis in darkness. This versatility is appropriate in photosynthetic organelles isolated from photo-organotrophic cells.
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PMID:Synthetic abilities of Euglena chloroplasts in darkness. 392 91


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