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)

In the presence of Uropolinum (sodium and N-methylglucamine diatrizoate) the lactate production of erythrocytes was decreased in half of the cases studied. The addition of albumin showed a protective effect on glycolysis of red blood cells. A decrease in glutathione reductase and increase in glucose-6-phosphate dehydrogenase activity was observed in all cases. Acethylcholinesterase activity was unaffected by Uropolinum. The activities of phosphohexose isomerase, phosphofructokinase. aldolase and ATP-ase were decreased in some subjects and increased in the others. It may be attributed to individual sensitivity of some subjects to diatrizoates and is consistent with clinical observations.
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PMID:The effect of uropolinum, a diatrizoate contrast medium, on erythrocyte metabolism. 99 74

Soluble enzymes were immobilized and visualized by polyacrylamide gel slabs, impregnated with the incubation medium including auxiliary enzymes. The method has several advantages over existing techniques which make use of gel films or a semipermeable membrane. The diffusion of tissue compounds is effectively limited, while auxiliary enzymes may be operative. Moreover the viscosity of the medium is temperature-independent so that the incubation temperature can be varied. To demonstrate the suitability of the method glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, hexokinase, phosphoglucomutase and aldolase were visulaized in human or rat skeletal muscle. Cytosolic and mitochondrial glycerol-3-phosphate dehydrogenase were both visualized in the absence of added NAD+ and menadione. For the visualization of ATP producint enzymes, like creatine kinase and pyruvate kinase, the method is not suitable.
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PMID:Polyacrylamide gel technique for the histochemical demonstration of soluble enzymes. 105 94

1. Time-curves of insulin effects on energy-producing systems in different cellular compartments of rat diaphragm muscle have revealed: (a) a rapid (within minutes) and transient stimulatory effect of insulin on cytoskeletal phosphofructokinase and aldolase and mitochondrial hexokinase. (b) A slower and consistent stimulatory effect on glucose 1,6-bisphosphate level, with concomitant gradual activation of cytosolic phosphofructokinase. Fructose 2,6-bisphosphate levels were not changed by insulin. (c) Lactate concentration correlated with the stimulation of cytoskeletal and cytosolic glycolysis. 2. Calmodulin antagonists, trifluoperazine or CGS 9343B, prevented all these effects of insulin. 3. These results suggest that cytoskeletal glycolysis and mitochondrial oxidation are the source of ATP for the rapid actions of insulin, whereas cytosolic glycolysis is the source of ATP for the slow actions of insulin. Calmodulin is involved in all these effects of insulin.
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PMID:Sequence of insulin effects on cytoskeletal and cytosolic phosphofructokinase, mitochondrial hexokinase, glucose 1,6-bisphosphate and fructose 2,6-bisphosphate levels, and the antagonistic action of calmodulin inhibitors, in diaphragm muscle. 139 93

Creatine kinase isoenzymes (CK = ATP: creatine N-phosphoryl transferase, EC 2.7.3.2) were localized in situ in cryosections of intact sarcomeric muscle by immunocytochemical staining. Similar to cardiac muscle, spermatozoa and photoreceptor cells, mitochondrial-type CK (Mi-CK) localization in skeletal muscle was also restricted to mitochondria. Besides the well-documented localization of muscle-type (M-CK) at the M-line and at the sarcoplasmic reticulum, surprisingly, most of the sarcoplasmic M-CK was also highly compartmentalized and was mainly confined to the I-band. The localization of M-CK at the I-band coincided with that of adenylate kinase and aldolase. In intact muscle, the diffusion equilibrium decisively favours occupancy by all three enzymes of the I-band, with the acto-myosin overlap region of the A-band acting as a molecular sieve, excluding to a large extent all three enzymes from the acto-myosin overlap region. This indicates that in intact muscle, this region of the A-band may be less accessible in vivo to soluble, sarcoplasmic enzymes than thought before. If muscle were permeabilized by chemical skinning before fixation, I-band CK, as well as aldolase and adenylate kinase, were solubilized and disappeared from the myofibrils, but the fraction of M-CK which was specifically associated with the M-line remained bound to the myofibrils. Implications of these findings are discussed with respect to the functional coupling of I-band-CK with glycolysis, to the formation of large multienzyme complexes of glycolytic enzymes with CK and to the supply of energy for muscle contraction in general.
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PMID:In situ compartmentation of creatine kinase in intact sarcomeric muscle: the acto-myosin overlap zone as a molecular sieve. 140 Oct 38

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

1. We report here on a novel action of insulin which shows that the hormone stimulates binding of phosphofructokinase (PFK) and aldolase to muscle cytoskeleton. 2. This effect was demonstrated both in vivo, by injection of insulin, in the tibialis anterior and gastrocnemius muscles, as well as in vitro, in the isolated rat diaphragm muscle incubated with insulin. 3. Insulin exerted this effect at physiologic range of concentrations and very rapidly (about 50% stimulation of binding occurred within 1 min). 4. The possible physiological significance of this rapid action of insulin, is to provide local ATP, generated by the accelerated cytoskeletal glycolysis, for other rapidly insulin-stimulated membrane-cytoskeleton processes.
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PMID:Insulin rapidly stimulates binding of phosphofructokinase and aldolase to muscle cytoskeleton. 153 2

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

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 presence of glycolytic enzymes and a GLUT-1-type glucose transporter in rod and cone outer segments was determined by enzyme activity assays, glucose uptake measurements, Western blotting, and immunofluorescence microscopy. Enzyme activities of six glycolytic enzymes including hexokinase, phosphofructokinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, pyruvate kinase, and lactate dehydrogenase, were found to be present in purified rod outer segment (ROS) preparations. Immunofluorescence microscopy of bovine and chicken retina sections labeled with monoclonal antibodies against glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and lactate dehydrogenase have confirmed that these enzymes are present in rod and cone outer segments and not simply contaminants from the inner segments or other cells. Rod outer segments were also found to contain glucose transport activity as detected by 3-O-[14C]methylglucose uptake and exchange. The glucose transporter had a Km of 6.3 mM and a Vmax of 0.15 nmol of 3-O-methylglucose/s/mg of ROS membrane protein for net uptake and a Km of 29 mM and a Vmax of 1.06 nmol of 3-O-methylglucose/s/mg of ROS membrane protein for equilibrium exchange. These Km values for net uptake and equilibrium exchange are similar to values obtained for human red blood cells and are characteristic of GLUT-1-type glucose transporter. The transport was inhibited by both cytochalasin B and phloretin. Western blot analysis and immunofluorescence microscopy using type-specific glucose transporter antibodies indicated that both rod and cone outer segment plasma membranes have a GLUT-1 glucose transporter of Mr 45K as found in red blood cells and brain microsomal membranes. Solid-phase radioimmune competitive inhibition studies indicated that rod outer segment plasma membranes contained 15% the number of glucose transporters found in human red blood cell membranes and had an estimated density of 400 glucose transporter per micron2 of plasma membrane. These studies support the view that outer segments can generate energy in the form of ATP and GTP by anaerobic glycolysis to supply at least some of the energy requirements for phototransduction and other metabolic processes.
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PMID:Glycolytic enzymes and a GLUT-1 glucose transporter in the outer segments of rod and cone photoreceptor cells. 193 98


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