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)

Sialic acid has been assayed enzymatically by an immobilized two-enzyme system. The method includes cleavage of sialic acid to pyruvic acid by N-acetylneuraminic acid (NANA) aldolase and reduction of pyruvic acid by lactate dehydrogenase in the presence of NADH, which is followed photometrically at 349 nm. For the membrane preparation 5 units of lactate dehydrogenase and 1 unit of NANA-aldolase were used. The pH optimum of the reaction using potassium phosphate buffer was 7.0. This two-enzyme membrane remains 100% active for several weeks at 4 degrees C in the assay buffer and remains stable after performing experiments at 45 degrees C.
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PMID:An immobilized bienzyme system for assay of sialic acid. 287 18

The structural peculiarities of rabbit muscle aldolase accompanying enhancement of the aldolase activity in diabetes are described from the data of tryptophan phosphorescence at the room temperature and fluorescence polarization. It is shown that the pathology-concomitant conformational changes occur in both the hydrophobic part and NAD-binding site of the enzyme. The character of the structural changes in the hydrophobic part of the protein in diabetes and an increase in the enzymic activity are similar to that observed in normal aldolase after its interaction with NADH and are believed to be associated with the enhancement of the rigidity in the Trp-147 environment.
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PMID:[Structuro-functional characteristics of aldolase from rabbit muscles in diabetes]. 318 55

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 aldolase A binding to the lecithin liposomes (Kd = 2.4 +/- 0.1 X 10(-3) M) has been shown by the fluorescence and tryptophan phosphorescence at the room temperature. The interaction is accompanied by an increase in the phospholipid bilayer microviscosity, and some conformational changes in the hydrophobic part of the enzyme, pronouncing themselves in Trp-147 environment rigidity, decrease. The observation of membrane viscosity vs. incubation time revealed practically instant enzyme-membrane interaction and no gradual incorporation. The accessibility of the NAD-binding domain of aldolase for NADH in the liposome presence remains unaltered.
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PMID:[Interaction of aldolase A with lecithin liposomes]. 339 75

A detailed study of the glucose fermentation pathway and the modulation of catabolic oxidoreductase activities by energy sources (i.e., glucose versus lactate or fumarate) in Propionispira arboris was performed. 14C radiotracer data show the CO2 produced from pyruvate oxidation comes exclusively from the C-3 and C-4 positions of glucose. Significant specific activities of glyceraldehyde-3-phosphate dehydrogenase and fructose-1,6-bisphosphate aldolase were detected, which substantiates the utilization of the Embden-Meyerhoff-Parnas path for glucose metabolism. The methylmalonyl coenzyme A pathway for pyruvate reduction to propionate was established by detection of significant activities (greater than 16 nmol/min per mg of protein) of methylmalonyl coenzyme A transcarboxylase, malate dehydrogenase, and fumarate reductase in cell-free extracts and by 13C nuclear magnetic resonance spectroscopic demonstration of randomization of label from [2-13C]pyruvate into positions 2 and 3 of propionate. The specific activity of pyruvate-ferredoxin oxidoreductase, malate dehydrogenase, fumarate reductase, and transcarboxylase varied significantly in cells grown on different energy sources. D-Lactate dehydrogenase (non-NADH linked) was present in cells of P. arboris grown on lactate but not in cells grown on glucose or fumarate. These results indicate that growth substrates regulate synthesis of enzymes specific for the methylmalonyl coenzyme A path and initial substrate transformation.
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PMID:Regulation of carbon and electron flow in Propionispira arboris: relationship of catabolic enzyme levels to carbon substrates fermented during propionate formation via the methylmalonyl coenzyme A pathway. 341 Aug 21

Fructose-1,6-bisphosphate and triosephosphates have been separated by high performance liquid chromatography utilizing a SynChropack AX anion exchange column with 50-200 mM KH2PO4, pH 2.5-4.6 as mobile phase. The best resolution for each compound was reached in a system of 150 mM KH2PO4, pH 2.5. If radioactive fructose-1,6-bisphosphate as initial substrate was enzymatically converted in triosephosphates, the recoveries of metabolites after the precipitation and chromatographic procedures were higher than 95%. The concentration of radioactive 3-phosphoglycerate measured by liquid scintillation shows a good correlation (correlation coefficient: 0.997) with the spectrophotometrically determined concentration of NADH, which is formed from [U-14C]fructose-1,6-bisphosphate in equimolar concentration with 3-phosphoglycerate in aldolase and glyceraldehyde-3-phosphate dehydrogenase system. The method developed was applied to detect the inhibitory effect of triosephosphate isomerase on aldolase activity which takes place due to the heterologous complex formation.
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PMID:Quantitative determination of triosephosphates during enzymatic reaction by high performance liquid chromatography: effect of isomerase on aldolase activity. 355 36

Formation of a bienzyme complex of pig heart mitochondrial malate dehydrogenase and citrate synthase in a buffered system is demonstrated by means of a covalently attached fluorescent probe to citrate synthase. Assuming 1:1 stoichiometry of the enzymes in the complex, an apparent dissociation constant of 10(-6) M was calculated from fluorescence anisotropy measurements. The effect of various metabolites on the interaction was tested. NAD+, oxalacetate, citrate, ATP, and L(-)- or D(+)-malate had no effect on the association of the two enzymes, whereas alpha-ketoglutarate increased and NADH decreased it. The interaction of mitochondrial citrate synthase with cytosolic malate dehydrogenase was found to be much weaker, whereas interaction of citrate synthase with another cytosolic enzyme, aldolase, could not be detected. In kinetic experiments, the activation of malate dehydrogenase by citrate synthase was observed. The effect of pyridine nucleotides and alpha-ketoglutarate is discussed in relation to the direction of the metabolic flow of oxalacetate.
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PMID:Quantitation of the interaction between citrate synthase and malate dehydrogenase. 357 Dec 48

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

It is shown by the fluorimetric analysis that with the 1,2 M MgCl2-induced dissociation of rabbit muscle aldolase the tertiary structure of the resulted protomers (subunits) remains practically unchanged. Significant changes in the protomeric enzyme are provoked by subsequent addition of urea up to the concentration of 2,3 M, and are, evidently, manifested in a significant decrease in regularity of the hydrophobic part of aldolase and in possible transition of its Trp-147 into more polar environment. This transition is reflected in the longwave shift of the protein fluorescence maximum (lambda max) by 13 nm (from 320 to 333 nm). But the joint action of MgCl2 and urea does not lead to complete unfolding of the resulted protomeric enzyme. More deep structural alterations in the subunits occur on acidic dissociation, and lambda max shift in this case reaches 342 nm. Structural changes caused by MgCl2 and urea are concomitant with the increase of fluorescence quenchibility with NADH. Here a short-wave lambda max shift, being usually observed in native aldolase fluorescence quenching, is not registered. This mean that the photoselection of protein fluorophores does not occur. The results thus obtained produce an evidence that oligomerization endows aldolase protomers with enhanced stability.
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PMID:[Stabilizing effect of oligomerization on aldolase protomers in rabbit muscles]. 377 80

It is shown that the activity of aldolase synthesized in rabbit muscles under diabetes is higher than that at normal state. This fact is probably a result of some structural alterations in NAD-binding site with Trp-291 and -311 in it which overlaps a considerable part of C-terminal region of the protein. The hydrophobic part of the enzyme containing Trp-147 under diabetes seems to remain unaltered. This consideration is based on the longwave shift in aldolase fluorescence lambda max (from 320 to 324 nm) under this pathology, suggesting a transition of Trp-291 and -311 into more polar environment and is confirmed by the disappearance of the difference in lambda max in the NADH presence. The NADH-originated shift in lambda max position for the both proteins ended at the same wave-length at 314 nm. The position of lambda max at 324 nm resulting from possible structural modification of NAD-binding site under diabetes correlates with an increase in the Stern-Volmer quenching constant value (from 4359 to 7500 M-1 for aldolase under normal and diabetic states, respectively). These quenching data evidence in favour of the suggestion on the existence of two classes of tryptophanyls in the aldolase molecule.
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PMID:[Comparative study of the structural characteristics of aldolase in rabbit muscles in normal states and in alloxan diabetes]. 377 81


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