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 leg muscle of Calotes versicolor consists mainly of white fibers. They can be classified into small, intermediate and broad fibers according to their diameter and staining reaction. The histochemical study of some of the glycolytic enzymes such as aldolase, phosphorylase, lactic dehydrogenase (LDH) and alpha-glycerophosphate dehydrogenase (alpha-GPDH) is described in the muscle of normal, pancreactomized and insulin injected animals. Highest activity of all enzymes was observed in the small fibers, though they occur in negligiable amount (3%). The intermediate and broad fibers exhibited medial and lowest activities respectively. 24 h after the extirpation of the pancreas a considerable inhibition is noted in the activities of phosphorylase, LDH and alpha-GPDH. Induced inanition for 21 days ensued insignificant but gradual decrease and increase in the alpha-GPDH and phosphorylase activities respectively in both unoperated and operated animals. The aldolase shows its mere presence in normal and trace activity in pancreatectomized animals. The injection of insulin (40 i.u./kg) at the interval of 30 min, 60 min, 4 h, 12 h and 24 h is given. The activities of all enzymes is stimulated at 30 min and depleted 4 h after the injection. The level of activity was remaintained at 12 h to 24 h stage. The possible physiological role and significance of enzymes in the synthesis and breakdown of glycogen is discussed.
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PMID:The influence of fasting and pancreatectomy on some glycolytic enzymes in the muscle of garden lizard, Calotes versicolor. 122 55

The 11.5-kDa Zn(2+)-binding protein (ZnBP) was covalently linked to Sepharose. Affinity chromatography with a cytosolic subfraction from liver resulted in purification of a predominant 38-kDa protein. In comparable experiments with brain cytosol a 39-kDa protein was enriched. The ZnBP-protein interactions were zinc-specific. Both proteins were identified as fructose-1,6-bisphosphate aldolase. Experiments with crude cytosol showed zinc-specific interaction of additional enzymes involved in carbohydrate metabolism. From liver cytosol greater than 90% of the following enzymes were specifically retained: aldolase, phosphofructokinase-1, hexokinase/glucokinase, glucose-6-phosphate dehydrogenase, glycerol-3-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-1,6-bisphosphatase. Glucose-6-phosphate isomerase, phosphoglycerate kinase, enolase, lactate dehydrogenase, and most of triosephosphate isomerase remained unbound. From L-type pyruvate kinase only the phosphorylated form seems to interact with ZnBP. Using brain cytosol hexokinase, phosphofructokinase-1, and aldolase were completely bound to the affinity column, whereas glucose-6-phosphate isomerase, phosphoglycerate kinase, enolase, lactate dehydrogenase, pyruvate kinase, and most of triose-phosphate isomerase remained unbound. The behavior of glucose-6-phosphate dehydrogenase and glycerol-3-phosphate dehydrogenase from this tissue could not be followed. A possible function of ZnBP in supramolecular organization of carbohydrate metabolism is proposed.
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PMID:Key enzymes of carbohydrate metabolism as targets of the 11.5-kDa Zn(2+)-binding protein (parathymosin). 183 54

Kinetics of fructose-1,6-disphosphate aldolase (EC 4.1.2.13) catalyzed conversion of fructose phosphates was analyzed by coupling the aldolase reactions to the metabolically sequential enzyme, glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), which interacts with aldolase. At low enzyme concentration poly(ethylene glycol) was added to promote complex formation of aldolase and glycerol-phosphate dehydrogenase resulting in a 3-fold increase in KM of fructose-1,6-bisphosphate and no change in Vmax. Kinetic parameters for fructose-1-phosphate conversion changed inversely upon complex formation: Vmax increased while KM remained unchanged. Gel penetration and ion-exchange chromatographic experiments showed positive modulation of the interaction of aldolase and dehydrogenase by fructose-1,6-bisphosphate. The dissociation constant of the heterologous enzyme complex decreased 10-fold in the presence of this substrate. Fructose-1-phosphate or dihydroxyacetone phosphate had no effect on the dissociation constant of the aldolase-dehydrogenase complex. In addition, titration of fluorescein-labelled glycerol-phosphate dehydrogenase with aldolase indicated that both fructose-1,6-bisphosphate and fructose-2,6-biphosphate enhanced the affinity of aldolase to glycerol-phosphate dehydrogenase. The results of the kinetic and binding experiments suggest that binding of the C-6 phosphate group of fructose-1,6-bisphosphate to aldolase complexed with dehydrogenase is sterically impeded while saturation of the C-6 phosphate group site increases the affinity of aldolase for dehydrogenase. The possible molecular mechanism of the fructose-1,6-bisphosphate modulated interaction is discussed.
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PMID:Modulation of the interaction between aldolase and glycerol-phosphate dehydrogenase by fructose phosphates. 206 91

The genes encoding glycolytic enzymes in Drosophila form a group of functionally related genes that may be coordinately regulated and thus controlled by common factors. We have examined the effect of dietary carbohydrates and ethanol on expression of the genes encoding glycerol-3-phosphate dehydrogenase (GPDH), aldolase (ALD), and phosphoglycerate kinase (PGK) in D. melanogaster larvae. GPDH activity and transcript abundance increased in response to ethanol and additional amounts of several different carbohydrates. In addition, the levels of two alternatively processed Gpdh transcripts were differentially regulated by the treatments. The nutritional conditions tested had little or no effect on the activities and transcript levels of ALD and PGK. These results indicate that changes in dietary conditions affect expression of specific genes and do not evoke a general response from genes involved in cellular metabolism. The observation that dietary carbohydrates and ethanol increase Gpdh expression without affecting expression of Ald and Pgk reinforces previous suggestions that dietary carbon can be diverted by GPDH from glycolytic catabolism into lipid biosynthesis.
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PMID:Effect of dietary carbohydrates and ethanol on expression of genes encoding sn-glycerol-3-phosphate dehydrogenase, aldolase, and phosphoglycerate kinase in Drosophila larvae. 212 75

We have developed a method for the simultaneous purification of hexokinase, glucosephosphate isomerase, phosphofructokinase, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase, D-glyceraldehyde-phosphate dehydrogenase, phosphoglycerate kinase, glycerol-3-phosphate dehydrogenase and glycerol kinase from Trypanosoma brucei in yields varying over 8-55%. Crude glycosomes were prepared by differential centrifugation of cell homogenates. Subsequent hydrophobic interaction chromatography on phenyl-Sepharose resulted in six pools containing various mixtures of enzymes. These pools were processed via affinity chromatography (immobilized ATP), hydrophobic interaction chromatography (octyl-Sepharose) and ion-exchange chromatography (CM- and DEAE-cellulose) which resulted in the purification of all nine enzymes. The native enzyme and subunit molecular masses, as determined by gel filtration and gel electrophoresis under denaturing conditions, were compared with those of their homologous counterparts from other organisms. Trypanosomal hexokinase is a hexamer and differs in subunit composition from the mammalian enzymes (monomers) as well as in subunit size (51 kDa versus 96-100 kDa, respectively). Phosphofructokinase only differs in subunit size (51 kDa for T. brucei versus 80-90 kDa for mammals) but had identical subunit composition (tetrameric). The others all have the same subunit composition as their mammalian counterparts. Except for triosephosphate isomerase, all Trypanosoma enzymes have subunits which are 1-5 kDa larger in size. Together these nine enzymes contribute 3.3 +/- 1.6% to the total cellular protein of T. brucei and at least 90% to the total glycosomal protein. A comparison of calculated intraglycosomal concentrations of the enzymes with the glycosomal metabolite concentrations shows that in the case of aldolase, glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase, the concentration of active sites is of the same order of magnitude as that of their reactants. A common feature of the glycosomal glycolytic enzymes (with the exception of glucosephosphate isomerase) is that they are highly basic proteins with pI values between 8.8 and 10.2, values which are 1-4 higher than in the case of their mammalian cytosolic counterparts and 3-6 higher than in the case of the various unicellular organisms. It is suggested that both the larger subunit size and the basic character of the T. brucei glycolytic proteins are involved in the routing of the enzymes from their site of biogenesis (the cytosol) towards their site of action (the glycosome).
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PMID:Glycolytic enzymes of Trypanosoma brucei. Simultaneous purification, intraglycosomal concentrations and physical properties. 294 90

Srivastava and Bernhard [Srivastava, D. K. & Bernhard, S. A. (1986) Science 234, 1081-1086] have proposed that glycolytic enzymes form multienzyme complexes for the direct transfer of metabolites from the producing enzyme to the utilizing one. We have reinvestigated the evidence for direct transfer of NADH between its complexes with alpha-glycerol-3-phosphate dehydrogenase (GPDH; EC 1.1.1.8) and L-lactate dehydrogenase (LDH; EC 1.1.1.27). The results reveal the following. (i) Proper treatment of the kinetics of and equilibrium data for the transfer of NADH between GPDH and LDH indicates that NADH transfer proceeds by a free-diffusion mechanism and not by direct transfer through a ternary complex. (ii) The koff for NADH from its GPDH complex is 60 sec-1 rather than 9.4 sec-1 in Tris.HCl buffer (pH 7.4) at 25 degrees C. With this value one can explain kcat = 50 sec-1 for LDH-catalyzed hydrogenation of pyruvate with GPDH-bound NADH as coenzyme. (iii) Steady-state kinetics show that LDH inhibits the GPDH-catalyzed reaction simply by reducing the concentration of free NADH. Similarly, aldolase inhibits the GPDH-catalyzed reduction of dihydroxyacetone phosphate to glycerol-3-phosphate by binding to the substrate. The proposed direct transfer of NADH between GPDH and LDH is therefore mainly based on a misinterpretation of the experimental data.
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PMID:Reexamination of the kinetics of the transfer of NADH between its complexes with glycerol-3-phosphate dehydrogenase and with lactate dehydrogenase. 319 95

The protozoan haemoflagellate Trypanosoma brucei, differs from other eukaryotic cells in that it contains nine enzymes involved in glucose and glycerol metabolism which are associated with microbody-like organelles called glycosomes. The information available to date indicates that glycosomal enzymes are synthesized as polypeptides of mature size. For three of them, glyceraldehyde-phosphate dehydrogenase, aldolase and glycerol-3-phosphate dehydrogenase, it has been shown that they are made on free polysomes in the cytosol and are subsequently transferred to the glycosome without any secondary modification. The topogenic signal responsible for import into the glycosome must, therefore, be present in the mature protein. Remarkable differences exist between the latter proteins and other glycolytic enzymes: (i) most glycosomal proteins have an apparent Mr which is 1-5 kDa larger than their homologous counterparts from the cytosol, or from other organisms; (ii) they have a high net positive charge. Based on the modelling of three glycosomal sequences in the respective homologous structures, it is thought that the topogenic signal may consist of a unique insertion, containing one or more basic amino acids which, together with additional positive charges elsewhere, constitute two positive hot spots approximately 4 nm apart on the surface of the protein. Such common elements, unique for the glycolytic enzymes from the Trypanosomatidae, lend themselves as excellent targets for the development of new drugs.
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PMID:Topogenesis of glycolytic enzymes in Trypanosoma brucei. 333 63

A method for determining Control Coefficients is proposed for systems studied in vitro and applied to a model pathway. Rat liver extract, which converts glucose into glycerol 3-phosphate, was used with the addition to the incubation mixture of fructose-bisphosphate aldolase, triose-phosphate isomerase and glycerol-3-phosphate dehydrogenase as 'auxiliary' enzymes, which leaves all the control on the first three enzymes. The flux of the metabolic pathway was recorded by assaying NADH decay. Flux Control Coefficients (CJE) of hexokinase, glucose-6-phosphate isomerase and phosphofructokinase were calculated by titration of the system with increasing quantities of extraneous enzymes. It is shown that the summation property is fulfilled. The applicability of this procedure to study the control in any metabolic pathway is discussed. Possible relevance of the method to conditions in vivo and its limitations are considered.
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PMID:Kinetics of metabolic pathways. A system in vitro to study the control of flux. 370 39

The glycosomes of in vitro grown procyclic trypomastigote forms of Trypanosoma brucei were purified by three different procedures and the results compared by electron microscopy, enzyme assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Centrifugation on a self-forming Percoll gradient followed by a sucrose gradient centrifugation resulted in the least enriched glycosomal preparation. Centrifugation on a pre-formed Nycodenz gradient gave an improved preparation but the most homogeneous preparation of intact glycosomes was obtained after centrifugation on two successive sucrose gradients. Glycosomes purified by both the Nycodenz and double sucrose gradient procedures appeared larger than in situ glycosomes presumably due to an osmotic effect resulting from disruption of the granular matrix of the organelles. Nevertheless, there appears to be no loss of cisternal contents due to the swelling of the organelles. The glycosomes of the bloodstream form trypomastigotes purified by the same procedures show, however, no sign of swelling. A comparison of glycosomes purified from procyclic trypomastigotes and bloodstream form trypomastigotes prepared by the same double sucrose procedure demonstrated that in the glycosome of procyclic trypomastigotes: activities of hexokinase, phosphoglucose isomerase, phosphofructose kinase, aldolase and phosphoglycerate kinase and diminished by 80-100%; activities of glyceraldehyde-3-phosphate dehydrogenase, triose phosphate isomerase and glycerol-3-phosphate dehydrogenase remain unchanged or are only slightly reduced; there is an appearance of four major new proteins, among which could be phosphoenol pyruvate carboxykinase and malate dehydrogenase. These observations are in basic agreement with those by Hart et al. (Mol. Biochem. Parasitol. 12, 25-35, 1984).
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PMID:An improved purification of glycosomes from the procyclic trypomastigotes of Trypanosoma brucei. 380 43

Glycosomes, the microbody-like organelles containing mainly glycolytic enzymes, were purified from the long slender bloodstream form of Trypanosoma brucei EATRO 110 monomorphic strain by an improved method in which the protozoa were frozen and thawed in 15% glycerol to free, from the plasma membrane, much of the variant surface glycoprotein which used to constitute the major contaminant of our purified glycosomes. The purified glycosomes have 11 major proteins, 6 of which, tentatively identified as phosphofructose kinase, hexokinase, 3-phosphoglycerate kinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, and alpha-glycerophosphate dehydrogenase, constitute 87% of the total glycosomal protein. The bifunctional cross-linking reagents dimethyl suberimidate and dimethyl-3,3'-dithiobispropionimidate can penetrate the glycosomal membrane and cause extensive cross-linking of all the major glycosomal proteins. The cross-linked complex, insoluble in 0.1% Triton X-100 plus 0.15 M NaCl, contains all the glycosomal enzyme activities with only partial inactivations. All the enzymes are probably cross-linked into one large complex since they all sediment rapidly to the bottom of a 5-20% (v/v) sucrose density gradient. This successful cross-linking with reagents of span lengths of 11-12 A suggests close proximities among the glycosomal enzymes which may explain the extraordinarily high rate of glycolysis in T. brucei. Whether such a close association represents specific spatial arrangement required for genuine substrate channeling among the enzymes will be verified by future kinetic studies of the cross-linked enzyme complex.
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PMID:Cross-linking of the enzymes in the glycosome of Trypanosoma brucei. 399 56


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