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)

We have been using the glycolytic enzyme fructose-bisphosphate aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate lyase, EC 4.1.2.13) as a model system to investigate the assembly of oligomeric enzymes. In the present work, we investigate the effect of specific, limited tryptic modification on the properties of aldolase isolated from wheat germ. The wheat-germ enzyme was selected, since several aldolases isolated from animal sources were not readily susceptible to the specific tryptic modification seen with this plant enzyme. We will show that: Low levels of trypsin cause a first-order inactivation of wheat-germ aldolase activity which is associated with a fairly specific cleavage of the enzyme which reduces its subunit molecular weight from 41000 to 39000. The proteolytic modification is greatly inhibited in the presence of the aldolase substrate, fructose bisphosphate. The intact and modified enzymes appear to have similar surface changes, as judged by their behavior during electrophoresis in polyacrylamide gels under non-denaturing conditions. The modified aldolase is not specifically eluted from phosphocellulose columns by fructose bisphosphate under the conditions used in the affinity chromatographic isolation of the intact enzyme, suggesting that the modified enzyme may no longer be able to bind substrate. Although enzymatically inactive, the modified aldolase subunits are able to refold and reassociate into tetrameric combinations following unfolding of the subunits by treatment at low pH; thus, this specific proteolytic modification does not interfere with the ability of wheat-germ aldolase subunits to refold and to establish precise subunit-subunit recognition in vitro.
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PMID:Specific, limited tryptic modification of wheat-germ fructose-bisphosphate aldolase subunits: destruction of catalytic activity but not of ability to establish precise subunit-subunit recognition. 394 58

Aldolase with a specific activity of 10.8 units/mg protein was isolated from pig muscle. Its molecular weight was found to be 150,000. The optimum pH for the catalytic activity was 7.25 and the apparent temperature optimum was 313 K. The Km value was 2.9 X 10(-5) M with FDP as substrate, and 2.8 X 10(-3) M with F1P as substrate. The thermal stability of this pig muscle enzyme was higher than that of the rabbit muscle enzyme. The thermal inactivation of the pig aldolase did not show simple first-order kinetics. The higher conformational stability of the pig aldolase than that of the rabbit enzyme was demonstrated by its higher resistance to the denaturing effect of urea.
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PMID:Isolation and characterization of pig muscle aldolase. A comparative study. 399 25

Dihydroxyacetone phosphate (DHAP) in equilibrium with FDP aldolase of muscle is present in the form of two major covalent complexes. One, representing approximately 60% of total bound substrate, decomposes to Pi and methylglyoxal upon acid denaturation of the enzyme as first reported by Grazi and Trombetta [Grazi, E., & Trombetta, G. (1979) Biochem. J. 175, 361-365]. This is now shown to be the enzyme-eneamine phosphate reaction intermediate since Pi formation is prevented if the acid denaturation is done in the presence of potassium ferricyanide, an oxidant of the eneamine. The enzyme-eneamine aldehyde X Pi 6, presumed to be an intermediate of the slow methylglyoxal synthetase reaction of aldolase, must not be a significant source of the Pi produced upon denaturation and is probably not a significant component of the equilibrium. The oxidation product, the enzyme-imine of phosphopyruvaldehyde, is sufficiently stable in 1 N HCl, t1/2 = 76 min at 0 degree C, to be isolated with the trichloroacetic acid precipitated protein. A second covalent complex, approximately 20-24% of bound dihydroxyacetone [32P]phosphate, remains with the protein during acid denaturation and centrifugation. This acid-stable complex is formed rapidly and is chased rapidly by unlabeled substrate. Its stability in 1 N HCl is similar to that of the ferricyanide-oxidized derivative mentioned above. From this and its reactivity with cyanoborohydride in acid, this complex is thought to be the imine adduct of DHAP with aldolase 4 and/or the carbinolamine complex 3 present in the initial equilibrium. D-Glyceraldehyde 3-phosphate in the carbonyl form also forms an acid-precipitable complex with aldolase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Chemical trapping of complexes of dihydroxyacetone phosphate with muscle fructose-1,6-bisphosphate aldolase. 405 77

Spirillum itersonii ATCC 12639 utilized d-fructose but neither d-glucose nor d-gluconate as a sole source of carbon and energy. The substrate saturation kinetics for d-fructose and d-glucose uptake by whole cells indicated the presence of a carrier-mediated transport system for d-fructose but not for d-glucose. The d-fructose uptake activity was induced (10- to 12-fold increase) during growth on d-fructose-Casamino Acids (CA) or d-glucose-CA medium, but not CA alone. d-Fructose uptake activity was stimulated by Na(+) or Li(+), but was inhibited by KCN, NaN(3), 2,4-dinitrophenol, and p-chloromercuribenzoate. High specific activities of glucokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydratase, and 2-keto-3-deoxy-6-phosphogluconate aldolase were detected in extracts of cells cultured on d-fructose-CA medium. These enzymatic activities were undetectable in extracts of cells grown in CA or succinate-CA medium. No decrease in the maximally induced specific activities of these enzymes occurred after the addition of succinate to cells during exponential growth on d-fructose-CA. Fructose 1,6-diphosphate aldolase and glucose-6-phosphate isomerase specific activities were approximately the same irrespective of cultural conditions. These results indicated that d-glucose was not utilized by cells of S. itersonii because this bacterium was impermeable to this hexose.
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PMID:Transport and catabolism of D-fructose by Spirillum itersomii. 480 97

Fructose 1,6-diphosphate aldolase from cells of Bacillus cereus appears to be typical Class II aldolase as judged by its functional and physical properties. Spore and vegetative cell aldolase had similar enzymatic, immunochemical, and heat resistance properties in the absence of calcium, but they differed in their thermal stabilities in the presence of calcium, their Stokes' radii, their mobility in acrylamide gel electrophoresis, and their molecular weights. The pH optimum for both enzymes was 8.5, and their K(m) with respect to substrate was 2 x 10(-3)m. Highly purified spore and vegetative cell aldolases were both heat labile with half-lives of 4 min at 53 C and pH 6.4. In the presence of 3 x 10(-2)m solution of calcium ions, the stability of the spore protein increased 12-fold but the vegetative form became more heat labile. The enhanced stability of the spore aldolase was not diminished by dialysis or gel filtration but was lost after chromatography on diethylaminoethyl cellulose at pH 7.4. Aldolase from vegetative cells exists in an equilibrium mixture of two molecular weights, 115,000 and 79,000 in the approximate ratio of 1:4, respectively. The molecular weight of spore aldolase is 44,000. Spore aldolase was more mobile during electrophoresis than its vegetative cell counterpart because of its smaller size.
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PMID:Properties of fructose 1,6-diphosphate aldolases from spores and vegetative cells of Bacillus cereus. 497 85

The effect of phosphorylation of bovine erythrocyte membrane on association of Fructose 1,6-diphosphate (FDP) aldolase has been investigated. The phosphorylation of the membrane seemed to favour the increased association of the enzyme. With the native and NaCl-depleted membrane, it was observed that the extent of phosphorylation could be correlated with the enzyme association. The experiments with the intact erythrocytes isolated from bovine and rabbit blood employing similar conditions, confirmed these findings. The observations with the membrane and whole cells have been substantiated using [gamma-32P]ATP and [32P] inorganic phosphate. The treatment of the enzyme favouring phosphorylation, did not show association of the enzyme with the membrane. The chemical modification of the membrane, influencing the association of the enzyme could be a possible mechanism for fine regulatory control of the activity.
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PMID:Mechanism of aldolase binding to erythrocyte membrane: Part I. Effect of membrane phosphorylation on aldolase association. 608 3

The activities of phosphofructokinase, aldolase and pyruvate kinase were diminished in extracts from skeletal muscle of streptozotocin diabetic rats, whereas the activities of glucose phosphate isomerase and phosphoglucomutase were not changed. Treatment of diabetic rats with insulin restored the activity of phosphofructokinase to normal. A kinetic study of the partially purified enzyme from normal and diabetic rats showed identical Michaelis constants for ATP and equal sensitivity to inhibition by excess of this substrate. Extracts of quick frozen muscle from diabetic rats had higher levels of citrate (an inhibitor of phosphofructokinase) and lower levels of D-fructose-1,6-bisphosphate and D-glucose-1,6-bisphosphate (activators of this enzyme). The levels of D-fructose-6-phosphate, D-glucose-6-phosphate, ATP, ADP and AMP were the same for the two groups. Our data suggest that the in vivo decrease of phosphofructokinase activity in skeletal muscle of diabetic rats is due to a decrease in the level of the enzymatically active protein as well as to an unfavorable change in the level of several of its allosteric modulators.
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PMID:Decreased phosphofructokinase activity in skeletal muscle of diabetic rats. 623 37

The ability of rabbit liver aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphatate-lyase, EC 4.1.2.13) and rabbit liver fructose-1,6-bisphosphatase (Fru-P2ase; D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) to partition into the gel phase of Ultrogel AcA 34 is decreased in a mixture of the two enzymes. Titration experiments indicate that a 1:1 complex is formed. The value for the distribution coefficient of the complex corresponds to a molecular mass of 300,000 daltons, the value expected for a dimer containing one mole of each enzyme protein. Complex formation was not observed when either liver enzyme was replaced by the corresponding isozyme from rabbit muscle. The susceptibility of liver Fru-P2ase to limited proteolysis by subtilisin was reduced in the presence of liver aldolase, but not when the latter was replaced by muscle aldolase, suggesting that the conformation of Fru-P2ase is altered in the complex. Limited proteolysis of liver aldolase abolishes its ability both to form the heterodimer and to protect Fru-P2ase from modification by subtilisin.
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PMID:Evidence for formation of a rabbit liver aldolase--rabbit liver fructose-1,6-bisphosphatase complex. 625 99

A histochemical multi-step technique for the demonstration of phosphofructokinase activity in tissue sections is described. With this technique a semipermeable membrane is interposed between the incubating solution and the tissue sections preventing diffusion of the non-structurally bound enzyme into the medium during incubation. In the histochemical system the enzyme converts the substrate D-fructose-6-phosphate to D-fructose-1,6-diphosphate, which in turn is hydrolyzed by exogenous and endogenous fructose diphosphate aldolase to dihydroxyacetone phosphate and D-glyceral-dehyde-3-phosphate. The dihydroxyacetone phosphate is reversibly converted into D-glyceraldehyde-3-phosphate by exogenous and endogenous triosephosphate isomerase. Next the D-glyceraldehyde-3-phosphate is oxidized by exogenous and endogenous glyceraldehyde-3-phosphate dehydrogenase into 1,3-diphospho-D-glycerate. Concomitantly the electrons are transported via NAD+, phenazine methosulphate and menadione to nitro-BT. Sodium azide and amytal are incorporated to block electron transfer to the cytochromes.
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PMID:Histochemical technique for the demonstration of phosphofructokinase activity in heart and skeletal muscles. 644 32

The nature of binding of FDP aldolase to bovine erythrocyte membrane was examined. The Km value of bound and soluble enzyme differed by an order. The absence of time-lag in the velocity-time curves at various concentrations of the substrate and the similar extent of inactivation of bound and soluble enzyme on heat treatment suggested that the enzyme was bound at a point other than the catalytic site. The release of the enzyme by various glycolytic intermediates suggested their involvement in binding to the catalytic site through phosphate linkage. The non-phosphorylated compounds like lactate, reduced glutathione, 2-mercaptoethanol and EDTA were ineffective in eluting the enzyme. On the basis of separate binding sites on the enzyme for membrane and ligands, the mechanism of association dissociation of aldolase has been suggested.
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PMID:Mechanism of aldolase binding to erythrocyte membrane: Part II. Kinetic aspects. 667 17


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