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 effect of estradiol-17 beta on the activities of glycolytic enzymes from female rat brain was studied. The following enzymes were examined: hexokinase (HK, EC 2.7.1.1), phosphofructokinase (PFK, EC 2.7.1.11), aldolase (EC 4.1.2.13), glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12), phosphoglycerate kinase (EC 2.7.2.3), phosphoglycerate mutase (EC 2.7.5.3), enolase (EC 4.2.1.11) and pyruvate kinase (PK, EC 2.7.1.40). The activities of HK (soluble and membrane-bound), PFK and PK were increased after 4 h of hormone treatment, while the others remained constant. The changes in activity were not seen in the presence of actinomycin D. The significant rise of the activities of the key glycolytic enzymes was also observed in the cell culture of mouse neuroblastoma C1300 treated with hormone. Only three of the studied isozymes, namely, HKII, B4 and K4 were found to be estradiol-sensitive for HK, PFK and PK, respectively. The results obtained suggest that rat brain glycolysis regulation by estradiol is carried out in neurons due to definite isozymes induction.
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PMID:Rat brain glycolysis regulation by estradiol-17 beta. 153 2

The association of glycolytic enzymes with the particulate fraction of the cell was assessed in the brain of the freshwater turtle, Pseudemys scripta elegans, using three different methodologies. Each method showed that a large percentage of each of eight enzymes was bound in brain. The effect of environmental anoxia (5 or 20 h submergence in N2-bubbled water at 7 degrees C) on the distribution of enzymes between free and bound states was analyzed. All three techniques showed a significant increase in the percentages of brain aldolase and glyceraldehyde-3-phosphate dehydrogenase bound during anoxia and no change in lactate dehydrogenase or creatine kinase binding. Two methodologies also showed an increase in the percent bound during anoxia for hexokinase, phosphofructokinase, and phosphoglycerate kinase. An increased association of glycolytic enzymes with structural elements of the cell during anoxia may physically position the glycolytic pathway to facilitate coupling between this ATP-generating pathway and ATP-utilizing processes, such as membrane ion pumps.
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PMID:Subcellular enzyme binding and the regulation of glycolysis in anoxic turtle brain. 153 98

The bound fractions of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and of fructose 1,6-diphosphate aldolase (ALD) were measured in intact Taenia coli. ALD was approximately 60% bound and GAPDH was approximately 41% bound. Bound ALD activity remaining in chemically demembranated Taenia coli was similar to that in intact tissue indicating a localization to the contractile apparatus. ALD was found to be specifically bound in the demembranated preparation. Chemical demembranation resulted in almost complete loss of all GAPDH activity indicating a localization of bound GAPDH to cellular membranes.
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PMID:Localization of two glycolytic enzymes in guinea-pig taenia coli. 155 49

The random diffusion mechanism is usually assumed in analyzing the energetics of specific pathways despite the findings that enzymes associate with each other and (or) with various membranous and contractile elements of the cell. Successive glycolytic enzymes have been shown to associate in the cytosol as enzyme complexes or bind to the thin filaments. Furthermore, the degree of glycolytic enzyme interactions have been shown to change with altered rates of carbon flux through the pathway. In particular, the proportions of aldolase, phosphofructokinase, and glyceraldehyde phosphate dehydrogenase bound to the contractile proteins have been found to increase with increased rates of glycolysis. In addition, decreasing pH and ionic strength are also associated with an increase in glycolytic enzyme interactions. The kinetics displayed by interacting enzymes generally serve to enhance their catalytic efficiencies. The associations of the glycolytic enzymes serve to enhance metabolite transfer rates, increase the local concentrations of intermediates, and provide for regulation of activity via effectors. Therefore these interactions provide an additional mechanism for regulating glycolytic flux in skeletal muscle.
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PMID:Regulation of skeletal muscle metabolism by enzyme binding. 158 49

Isolated skeletal muscle triads contain a compartmentalized glycolytic reaction sequence catalyzed by aldolase, triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, and phosphoglycerate kinase. These enzymes express activity in the structure-associated state leading to synthesis of ATP in the triadic junction upon supply of glyceraldehyde 3-phosphate or fructose 1,6-bisphosphate. ATP formation occurs transiently and appears to be kinetically compartmentalized, i.e., the synthesized ATP is not in equilibrium with the bulk ATP. The apparent rate constants of the aldolase and the glyceraldehyde-3-phosphate dehydrogenase/phosphoglycerate kinase reaction are significantly increased when fructose 1,6-bisphosphate instead of glyceraldehyde 3-phosphate is employed as substrate. The observations suggest that fructose 1,6-bisphosphate is especially effectively channelled into the junctional gap. The amplitude of the ATP transient is decreasing with increasing free [Ca2+] in the range of 1 nM to 30 microM. In the presence of fluoride, the ATP transient is significantly enhanced and its declining phase is substantially retarded. This observation suggests utilization of endogenously synthesized ATP in part by structure associated protein kinases and phosphatases which is confirmed by the detection of phosphorylated triadic proteins after gel electrophoresis and autoradiography. Endogenous protein kinases phosphorylate proteins of apparent Mr 450,000, 180,000, 160,000, 145,000, 135,000, 90,000, 54,000, 51,000, and 20,000, respectively. Some of these phosphorylated polypeptides are in the Mr range of known phosphoproteins involved in excitation-contraction coupling of skeletal muscle, which might give a first hint at the functional importance of the sequential glycolytic reactions compartmentalized in triads.
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PMID:Compartmentalized ATP synthesis in skeletal muscle triads. 173 94

Recent studies have demonstrated that most glycolytic enzymes can reversibly associate to form heterogeneous enzyme-enzyme (binary) complexes in vitro. However, kinetic analysis of these complexes has shown that the individual enzymes have a varied response to complex formation: some enzymes are inhibited, some are activated and some are unaffected. In order to determine the potential role of binary complexes in regulating glycolytic flux, we have mathematically calculated enzyme distributions and activities using data from in vitro binding and kinetic studies. These calculations suggest that, overall, formation of binary complexes would lower flux through phosphofructokinase and aldolase, would increase flux through glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase, and would not affect flux through triosephosphate isomerase, phosphoglycerate kinase and pyruvate kinase. The implications of these results are discussed with respect to the effect of complex formation on overall glycolytic flux and on the flux through individual enzyme loci.
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PMID:The effect of enzyme-enzyme complexes on the overall glycolytic rate in vivo. 180 92

P. falciparum lacks a functional citric acid cycle. Unlike most tissues of the mammalian host, it is totally dependent on glycolysis for energy generation. A compound which selectively inhibits the parasite's ATP-generating machinery is therefore a potential antimalarial agent. Such a drug may interact in two ways: a) by inhibiting the activity of an enzyme or b) by disturbing the micro-organization of consecutive enzymes in a metabolic pathway. In mammalian tissues the glycolytic pathway involves the cytoskeleton as a matrix to keep phosphofructokinase, aldolase and glyceraldehyde-3-phosphate dehydrogenase in an optimal sterical position for rapid substrate conversion. For instance, these three enzymes bind to the band 3 protein in erythrocytes or to actin in muscle cells. P. falciparum aldolase binds with very high affinity to the band 3 protein of human erythrocyte ghosts. However, the true in vivo site of association is believed to be actin II of P. falciparum. This actin has a sequence element which is almost identical to that of the band 3 aldolase binding site. We therefore suppose that plasmodia exploit a similar matrix organization. If true, the association of these enzymes with the cytoskeleton is a target for novel antimalarials. In contrast to all vertebrate aldolases, P. falciparum and P. berghei aldolases have two neighbouring lysine residues near the carboxy-terminus. We show here that mutagenesis of these basic residues has an effect on the catalytic constants Vmax and KM and moreover, the ability to bind to band 3 is reduced.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Is Plasmodium falciparum aldolase useful for rational drug design? 182 Jul 2

A quantitative histochemical method was developed for the demonstration in rat liver of the activity of phosphofructokinase, one of the enzymes assumed to be rate-limiting for glycolysis. The procedure was based on the reduction of a tetrazolium salt as final electron acceptor and a multistep reaction using the exogenous or endogenous auxiliary enzymes aldolase, triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase. The highest activity was found in unfixed cryostat sections of rat liver when the incubation medium contained 17% (wt/vol) polyvinyl alcohol, 100 mmol/L Tris-maleate buffer (pH 8.4), 20 mmol/L fructose-6-phosphate, 2 mmol/L ATP, 2 mmol/L MgCl2, 5.9 mmol/L NAD+, 0.47 mmol/L 1-methoxyphenazine methosulfate, 5 mmol/L sodium azide and 5 mmol/L Nitro BT. The addition of auxiliary enzymes was not necessary to demonstrate maximum activity in rat liver. The specificity of the reaction was proven by the absence of any specific (test minus control) reaction when the incubation was performed in the presence of 25 mmol/L phosphoenolpyruvate, a competitive inhibitor of phosphofructokinase. Cytophotometric analysis revealed that linear relationships exist between the amount of specific reaction product formed and incubation time and the section thickness. The Km values for fructose-6-phosphate and the Vmax values were not significantly different in periportal and pericentral areas of livers from either normally fed or 24-hr-fasted rats. The homogeneous distribution of phosphofructokinase activity in the liver acinus is in line with biochemical findings using hepatocytes isolated from the two different areas showing that these cells contained similar amounts of enzyme activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Homogeneous distribution of phosphofructokinase in the rat liver acinus: a quantitative histochemical study. 183 3

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

Previous studies had indicated that the form II or B cluster of CO2 fixation structural genes is part of a large operon in Rhodobacter sphaeroides (Gibson, J. L., Chen, J.-H., Tower, P. A., and Tabita, F. R. (1990) Biochemistry 29, 8085-8093). In this investigation, we have sequenced the DNA between the prkB and rbpL genes and provide evidence for three distinct open reading frames which encode additional structural genes of the Calvin reductive pentose phosphate pathway; these genes encode the enzymes transketolase, glyceraldehyde phosphate dehydrogenase, and aldolase. Noteworthy is transketolase, which may be expressed to high levels in Escherichia coli. This study thus represents the initial description of the primary structure of bacterial transketolase, a key enzyme of the reductive and the oxidative pentose phosphate pathways. Each of the genes are separated by short stretches of intergenic sequence, consistent with earlier evidence which suggested that these genes are cotranscribed and part of a large operon controlled by sequences upstream from fbpB.
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PMID:Identification, expression, and deduced primary structure of transketolase and other enzymes encoded within the form II CO2 fixation operon of Rhodobacter sphaeroides. 193 98


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