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 effects of exogenous and endogenous insulin and glucagon on aldolase turnover in rat liver and blood were studied. Some effects of these hormones on the biosynthesis and degradation of hepatic aldolase were specified. The rate of the "de novo" synthesis of aldolase was investigated in hepatocyte mitochondria and in blood plasma. The exogenous and endogenous hormones were shown to produce different effects on the biosynthesis and spontaneous degradation of rat liver aldolase.
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PMID:[Effect of insulin and glucagon on aldolase turnover in rat liver]. 635 74

A study was made of the effect of insulin on the rate of biosynthesis, "half life", spontaneous decomposition and transport of aldolase in mitochondria of liver and blood plasma of rats subjected to whole-body X-irradiation. The hormone injected after irradiation was shown to normalize the rate of spontaneous decay and the time of aldolase functioning.
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PMID:[Effect of insulin on the turnover of liver aldolase in irradiated rats]. 639 6

The purification of an enzyme is described, a protease, from human erythrocytes which degrades insulin with a high specificity at physiological hormone concentrations. Since the enzyme contains free sulfhydryl groups, affinity chromatography on organomercuri-Sepharose proved to be applicable as a valuable step in the isolation procedure. The purification factor amounted to approx. 6000, the yield to 8%. 1mg of purified enzyme was capable of degrading 50 pmol of insulin/min into trichloroacetic acid-soluble split products. The purified insulin-degrading enzyme was shown to be homogeneous, as demonstrated by gel chromatography, gel electrophoresis and isoelectric focusing. The isoelectric points was at pH 5.8. The molecular weight of nativ enzyme was estimated by gel chromatography and gel electrophoresis and found to be about 150 000-160 000, consisting of 4 subunits. Degradation products of insulin eluted from a Biogel P 30 column are smaller than the A-chain of the hormone, suggesting the activity of a protease. The enzyme appears to be specific for insulin in that it does not degrade other peptide hormones such as growth hormone, prolactin, or thyroid-stimulating hormone. Furthermore, the enzyme does not inactivate enzymes such as lactate dehydrogenase, aldolase, fructose 1,6-bisphosphatase, hexosephosphate isomerase or hexokinase.
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PMID:Purification to homogeneity of an insulin-degrading enzyme from human erythrocytes. 699 71

When leupeptin, a thiol protease inhibitor of microbial origin, was injected into rats, the activity of fructose-1,6-bisphosphate aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13) in the liver decreased to about 60% of that in control rats. However, the concentration of aldolase protein in the liver extracts, measured with a specific antibody obtained with enzyme purified on a phosphocellulose column, remained unchanged. Injection of leupeptin also caused a marked increase in the activities of free lysosomal proteases, such as cathepsin B (EC 3.4.22.1), cathepsin L (EC 3.4.22.-), cathepsin D (EC 3.4.23.5) and lysosomal carboxypeptidase A in the cytosol fraction. A clear inverse relationship between aldolase and cathepsin B activities in the cytosol fraction was demonstrated. The possibility that the less active form of aldolase detected in the livers of leupeptin-treated rats was produced during homogenization was excluded by showing that the aldolase activity was not changed by addition of various protease inhibitors to the homogenization medium., When insulin was coinjected with leupeptin, increase in the activity of free cathepsin L and decrease of activity of aldolase produced by the injection of leupeptin was prevented. These findings indicate that modification of aldolase may be due to the action of a lysosomal protease(s). Enhanced sensitivity of lysosomes to osmotic shock was demonstrated in the livers of leupeptin-treated rats, suggesting that the lysosomal membrane is labilized by administration of leupeptin. Incubation of the purified aldolase with the lysosomal fraction produced the same changes in properties of aldolase as those observed in vivo on injection of leupeptin.
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PMID:Proteolytic modification of rat liver fructose-1,6-bisphosphate aldolase by administration of leupeptin in vivo. 702 Jul 65

In vivo proteolytic modification of liver aldolase on administration of leupeptin, a thiol proteinase inhibitor of microbial origin, is reported. When leupeptin was injected into rats, the activity of aldolase in the liver decreased to 40% of that in control rats. Molecular properties of aldolase isolated from the livers of control rats and leupeptin-treated rats indicated that a decrease of aldolase activity is attributable to hydrolysis of a peptide linkage(s) near the carboxyterminal of the enzyme. Injection of leupeptin also caused marked increase in the activities of free lysosomal proteinases, such as cathepsin A and cathepsin D and moderate increase of cathepsin B and cathepsin L. Increase in free activity of cathepsin A returned to the level of control rats by 12 hr after injection of leupeptin, whereas 36 hr was required for recovery of decreased aldolase activity. When insulin was coinjected with leupeptin, increase in the activity of free cathepsin A and decrease of activity of aldolase produced by the injection of leupeptin was prevented. These findings indicate that modification of aldolase may be due to action of a lysosomal protease(s). Incubation of the purified aldolase with the lysosomal fraction produced the same changes in properties of aldolase as those observed in vivo on injection of leupeptin. The aldolase inactivating proteinase in the lysosomal fraction was inhibited by PMSF and leupeptin and not by pepstatin. Purified cathepsin A (a serine proteinase), cathepsin B and cathepsin L (thiol proteinase) are potent inactivators of aldolase but cathepsin H and cathepsin D are not. Cathepsin A, B and L are involved in inactivation of aldolase in lysosomes. Endogenous thiol proteinase inhibitor which inhibits lysosomal thiol proteinases (cathepsin B, L and H) is found in the cytosol fraction of liver. The level of thiol proteinase inhibitor actually decreased to 60% of that in control rats in leupeptin-treated rats, suggesting that non-thiol proteinase cathepsin A is a major factor in inactivation of aldolase in lysosomes. Not only leupeptin but also other proteinase inhibitors (antipain, E-64-D, chloroquine) caused increase of labilization of the lysosomes and decrease in aldolase activity. Physiological stimuli which are known to induce the labilization of the lysosomal membrane, such as starvation and glucagon, caused slight or no significant increase of activities of free cathepsin A and D and resulted in no apparent change in aldolase activity.
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PMID:Modification of rat liver fructose biphosphate aldolase by lysosomal proteinases. 705 71

Glycolytic enzymes are known to be controlled by reversible binding to cytoskeleton. Our previous experiments have shown that insulin, epidermal growth factor (EGF), and Ca2+ induce a rapid and transient stimulation of binding of glycolytic enzymes to muscle cytoskeleton. We show here that platelet-derived growth factor (PDGF) exerts a similar action. Incubation of rat diaphragm muscle in the presence of PDGF resulted in rapid and transient stimulation of binding of phosphofructokinase (EC 2.7.11) and aldolase (EC 4.1.2.13) to muscle cytoskeleton. The increase in cytoskeleton-bound glycolytic enzymes induced by PDGF was prevented by treatment with the calmodulin antagonists trifluoperazine or CGS 9343B (a potent and selective inhibitor of calmodulin activity), which strongly suggests that Ca(2+)-calmodulin is involved in this effect of PDGF. Similarly, we previously found that stimulation of cytoskeleton-bound glycolytic enzymes exerted by insulin, EGF, or Ca2+, was also calmodulin mediated. The present and previous results suggest that the rapid, Ca(2+)-calmodulin-mediated increase in cytoskeleton-bound glycolytic enzymes, may be a general mechanism in the cell, in signal transduction of insulin, growth factors, and other Ca(2+)-mobilizing hormones. The accelerated cytoskeletal glycolysis will provide local ATP, which is required for the rapid cytoskeletal-membrane rearrangements following binding of growth factor or hormone to its receptor.
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PMID:Platelet-derived growth factor (PDGF) rapidly stimulates binding of glycolytic enzymes to muscle cytoskeleton, prevented by calmodulin antagonists. 785 79

Hormonal inductions of lipogenic enzyme activities (fatty acid synthetase, malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PD) and ATP-citrate lyase) were studied in primary cultured rat hepatocytes. Insulin, triiodothyronine and dexamethasone markedly stimulated the inductions of the enzymes (particularly G6PD and ME) in the presence of pyruvate. Lactate also induced their activities. The activities of these enzymes in the presence of appropriate hormone combinations and a substrate amount of pyruvate were as high as, or higher than those in the liver of rats on high-carbohydrate, low-fat diet. The aldolase and glucokinase activities induced by these hormones were not enhanced by the addition of pyruvate. The induction by pyruvate was inhibited by actinomycin D or cycloheximide. The ATP content of rat hepatocytes was maintained without increase during culture with pyruvate for 6 days. These results indicate that the additions of pyruvate, or its metabolites to cultures of isolated hepatocytes have specific effects on the inductions of certain hepatic enzymes, possibly acting at the level of transcription. Their effects are similar to those of feeding a high-carbohydrate, low-fat diet to intact animals.
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PMID:Pyruvate stimulates hormonal induction of lipogenic enzymes in primary cultured rat hepatocytes. 821 43

1. We show here that treatment of diaphragm muscle with 2,4-dinitrophenol (DNP), an uncoupler of oxidative phosphorylation, abolished the stimulatory action of insulin on binding of the glycolytic enzymes, phosphofructokinase (PFK) and aldolase, to muscle cytoskeleton. This effect was demonstrated with low concentration of DNP, which caused only a small decrease in ATP and did not affect the basic levels of cytoskeleton-bound glycolytic enzymes. 2. Higher concentrations of DNP, which induced a drastic decline in ATP content, caused a decrease in cytoskeleton-bound glycolytic enzymes and damage to myofibrils. 3. These results suggest that mitochondrial ATP is required for both the preservation of the basal levels of cytoskeleton-bound glycolytic enzymes and cell structure, as well as for the expression of the stimulatory action of insulin on glycolytic enzymes' binding to muscle cytoskeleton.
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PMID:Uncoupling of mitochondrial oxidative phosphorylation abolishes the stimulatory action of insulin on the binding of glycolytic enzymes to muscle cytoskeleton. 836 51

We report here on a novel mechanism involved in epidermal growth factor (EGF) action, which shows that EGF rapidly stimulates binding of the glycolytic enzymes, phosphofructokinase (EC 2.7.1.11), and aldolase (EC 4.1.2.13) to muscle cytoskeleton. This effect was demonstrated both in vivo, in the tibialis anterior muscle from rats injected with EGF, and in vitro, in the isolated rat diaphragm muscle incubated with EGF. The increase in cytoskeleton-bound glycolytic enzymes induced by EGF was prevented, in both the in vivo and in vitro experiments, by treatment with the calmodulin antagonists trifluoperazine or CGS 9343B (a potent and selective inhibitor of calmodulin activity), which strongly suggests that Ca2+ and calmodulin are involved in this effect of EGF. Our previous findings have revealed that insulin or Ca2+ exert a similar rapid stimulation of cytoskeletal glycolysis, which is also calmodulin mediated. We now hypothesize that this may be a general mechanism of signal transduction in the cell, involving Ca(2+)-mobilizing hormones and growth factors, and supplying local ATP, in the vicinity of cytoskeleton-membrane, which is required for the rapid cytoskeletal-membrane rearrangements upon membrane-induced events.
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PMID:Stimulatory effect of epidermal growth factor on binding of glycolytic enzymes to muscles cytoskeleton and the antagonistic action of calmodulin inhibitors. 837 34

Some cysteine-containing proteins upon sulfitolysis have been found to show anomalously retarded SDS-PAGE mobilities in non-reducing gels. These proteins include bovine serum albumin, ovalbumin, aldolase, ribonuclease and a recombinant fusion protein (XA) consisting of a portion of gamma-interferon linked to the A chain of human insulin. This mobility shift has been employed to determine the stability of the sulfonated products and to study the kinetics of the sulfitolysis reaction. Partially sulfonated products of intermediate shifts were observed at 0.01% beta-ME, while 0.05% beta-ME gave a shift characteristic of the completely reduced protein. The undiluted sulfitolysis reagent reacted with XA to give within 1 min a gel shift characteristic of the fully sulfitolysed protein. Its transition stages could be visualized at 15, 30 and 60 min when the reagent was diluted four-fold. In the presence of 8 M urea, the sulfitolysis of BSA was nearly complete at 30 min when the sulfitolysis reagent was used at a dilution of 1:5. However, under the same conditions BSA was predominantly unsulfitolysed in the absence of urea. In order to elucidate the mechanism of sulfonation shift, several derivatives of XA, e.g. performic acid oxidized, alkylated with (a) iodoacetamide and (b) iodoacetate, have been prepared. While the mobility of XASSO3- was sensitive to the presence of beta-ME, all other derivatives moved in a beta-ME-insensitive fashion. Furthermore, while the nonreducing mobilities of the acidic derivatives (-SSO3-, -SO3- and -SCH2CO2-) were anomalously retarded and identical, the mobility of the iodoacetamide derivative was intermediate between the retarded acidic derivatives above and XA below. These studies have suggested a role of the extended conformation of the A chain of insulin in causing a mobility shift of the acidic derivatives in this series. Similar results were observed in an analogous series of derivatives prepared from BSA. Non-denaturing gel filtration analyses of native vs. sulfitolysed samples of serum albumin, ovalbumin and ribonuclease have indicated that the sulfitolysed proteins elute earlier than their native counterparts and appear to be significantly larger than their true molecular weights. Circular dichroism analysis has indicated significant loss in helicity of sulfitolysed BSA. This suggests that the retarded mobility of sulfitolysed proteins seen on SDS-PAGE is likely to be due to an expansion in the hydrodynamic volumes of these proteins, a phenomenon triggered by cleavage of disulfide bonds and further accentuated by the introduction of strongly negatively charged sulfonates.
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PMID:Anomalous mobility of sulfitolysed proteins in SDS-PAGE. Analysis and applications. 889 91


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