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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)

Phosphonoacetaldehyde hydrolase (EC 3.11.1.1), the bacterial enzyme that catalyses the reaction HCO-CH2-PO(OH)2+H2O leads to HCO-CH3+Pi, is inactivated by borohydride if either phosphonoacetaldehyde or acetaldehyde is present. This supports the suggestion that the substrate forms an imine with an amino group of the enzyme. Such imine formation would labilize the C-P bond in the same way that aldolase and related enzymes labilize C-C and C-H bonds (Scheme 1a).
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PMID:Aldolase-like imine formation in the mechanism of action of phosphonoacetaldehyde hydrolase. 20 Feb 22

The possibility of interaction between purified rabbit muscle aldolase and D-glyceraldehyde-3-phosphate dehydrogenase was studied by rapid kinetic methods, by analyzing the kinetics of the consecutive reaction catalyzed by the coupled enzyme system. The Km of the intermediary product, glyceraldehyde 3-phosphate, produced by aldolase was determined in the coupled reaction for glyceraldehyde-3-phosphate dehydrogenase. Its value corresponds to that of the aldehyde (active) form of glyceraldehyde 3-phosphate, although in the given conditions the aldehyde leads to diol interconversion is faster than the enzymic reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase. We suggest that above a certain concentration of the enzymes the glyceraldehyde 3-phosphate produced by aldolase gets direct access to glyceraldehyde-3-phosphate dehydrogenase without participating in the aldehyde leads to diol interconversion which otherwise would occur if the substrate were to mix with the bulk medium.
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PMID:Kinetic evidence for interaction between aldolase and D-glyceraldehyde-3-phosphate dehydrogenase. 20 15

In the reaction catalysed by deoxyribose 5-phosphate aldolase (2-deoxy-D-ribose 5-phosphate acetaldehyde-lyase, EC 4.1.2.4) from Salmonella typhimurium, almost complete equilibration of the methyl-group protons of the product, acetaldehyde, occurs before its release from the enzyme surface. This phenomenon does not allow the stereo-chemical course of the reaction to be determined by using hydrogen-isotope labelling of the methyl group to generate a chiral centre.
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PMID:An apparent lack of stereospecificity in the reaction catalysed by deoxyribose 5-phosphate aldolase due to methyl-group rotation and enolization before product release. 79 Dec 68

In 38 patients with chronic renal insufficiency of different degree of severity examinations of the stationary concentration of the adenine nucleotides in the erythrocytes were carried out. It was shown that in the red blood cells of uraemics a genuine increase of the concentration of these compounds occurs, in which case the adenosine triphosphate dominates absolutely as well as relatively. In individual cases erytho-cyctic ATP-values of more than 3 micron mol pro ml cells may be achieved. The increase of the ATP-concentration in the red blood cells correlates with the degree of severity of the renal insufficiency and the renal anaemia. The hyperphosphataemia occurring as a rule in renal insuficiency is of causal importance for the increase of ATP. By a consecutive increase of the intracellular phosphate level and by influence on different steps of enzymes (phosphofructokinase, aldolase, glycerin aldehyde phosphate dehydrogenase) and changed regulations it effected an activation of the glycolysis. The increase of the plasma adenine and plasma adenosine concentration plays apparantly an accessory role for the increase of the concentration of the adenine nucleotides existing in the erythrocytes. Together with an increased concentration of 2,3-diphosphogycerate (2,3-DPG) the increase of the ATP-level has an effect on the oxygen transport function function of haemoglobin in the sense of a facilitation of the O2-output. These processes explain the relative adaption of patients with chronic renal insufficiency to renal anaemias of partly high degree.
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PMID:[Adenine nucleotide- and 2,3-diphosphoglycerate metabolism in human erythrocytes in chronic kidney insufficiency]. 84 44

In Pseudomonas saccharophila 2-keto-3-deoxygalactonate-6-P aldolase (EC 4.1.2.21) is induced by growth on galatose while 2-keto-3-deoxygluconate-6-P aldolase (EC 4.1.2.14) is constitutive. These enzymes catalyze identical reactions except for the configuration fixed at C-4 during the condensation reaction. It was found with each enzyme that in a condensation between [3-3H3]pyruvate and D-glyceraldehyde-3-P, the respective condensation products were formed 8 to 10 times faster than tritium was released to water. Since pyruvate deprotonation is obligatory for condensation, the above result requires a hydrogen isotope effect in enolpyruvate formation, which must be then at least partially rate limiting for C--C synthesis. Further, condensation between D-glyceraldehyde-3-P and (3R)-[3-3H, 2H,H]pyruvate or (3S)-[3-3H, 2H,H]pyruvate, as catalyzed by each enzyme, enriched for (3R)- and (3S)-3-3H, 2H-labeled condensation product, respectively. Thus, each enzyme catalyzes C--C and C--H synthesis with retention of configuration at C-3. This shows that the active sites of both enzymes are asymmetric since solutes can only approach a single face of the bound pyruvyl enolate. In addition, the respective aldehyde specific portions of the two active sites must have opposite chiralities, with respect to each other, for correctly orienting the carbonyl faces of the incoming D-glyceraldehyde-3-P, to generate the correct configuration at C-4 of the respective condensation products.
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PMID:The sterochemistry at carbon 3 of pyruvate lyase condensation products. 2-Keto-3-deoxygluconate 6-phosphate and 2-keto-3-deoxygalactonate-6-phosphate aldolase of Pseudomonas saccharophila. 115 86

Pig muscle aldolase was covalently attached to a silica-based support possessing aldehyde functional groups. The activity of the immobilized enzyme was 37 U/g solid, and the specific activity calculated on a bound protein basis was 1.9 U/mg protein. The optimum pH for the catalytic activity was pH 7.5. The apparent optimum temperature was found to be 45 degrees C. The Km app value of the immobilized aldolase with D-fructose 1,6-diphosphate as substrate was 1.25 X 10(-4) M. The conformational stability was improved by the immobilization. The immobilized aldolase was used for the continuous splitting of D-fructose 1,6-diphosphate.
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PMID:Immobilization of pig muscle aldolase on a silica-based support. 255 62

Dissimilation of L-fucose as a carbon and energy source by Escherichia coli involves a permease, an isomerase, a kinase, and an aldolase encoded by the fuc regulon at minute 60.2. Utilization of L-rhamnose involves a similar set of proteins encoded by the rha operon at minute 87.7. Both pathways lead to the formation of L-lactaldehyde and dihydroxyacetone phosphate. A common NAD-linked oxidoreductase encoded by fucO serves to reduce L-lactaldehyde to L-1,2-propanediol under anaerobic growth conditions, irrespective of whether the aldehyde is derived from fucose or rhamnose. In this study it was shown that anaerobic growth on rhamnose induces expression of not only the fucO gene but also the entire fuc regulon. Rhamnose is unable to induce the fuc genes in mutants defective in rhaA (encoding L-rhamnose isomerase), rhaB (encoding L-rhamnulose kinase), rhaD (encoding L-rhamnulose 1-phosphate aldolase), rhaR (encoding the positive regulator for the rha structural genes), or fucR (encoding the positive for the fuc regulon). Thus, cross-induction of the L-fucose enzymes by rhamnose requires formation of L-lactaldehyde; either the aldehyde itself or the L-fuculose 1-phosphate (known to be an effector) formed from it then interacts with the fucR-encoded protein to induce the fuc regulon.
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PMID:Cross-induction of the L-fucose system by L-rhamnose in Escherichia coli. 330 11

Since red cells transport and metabolize acetaldehyde in vivo, the effects of acetaldehyde on human red cell enzyme activities were studied. Incubation of intact red cells or undiluted red cell lysates at 37 degrees C for 4 h with 1-10 mmol/l acetaldehyde decreased only GOT, GPT and aldolase activities among the 26 enzymes tested. No inhibition occurred at 4 degrees C or when acetaldehyde was incubated with dilute hemolysates. Incubation of lysates with other reducing substrates or with acetate inhibited aldolase but not GOT or GPT. Preincubation of lysates with cyanate or fluoride markedly decreased acetaldehyde-mediated transaminase inhibition but not aldolase inhibition. Addition of pyridoxal phosphate, the vitamin B6 transaminase coenzyme, to GOT and GPT assay mixes did not reverse acetaldehyde-mediated transaminase inhibition. These findings suggest that acetaldehyde-mediated aldolase inhibition results from oxidation of acetaldehyde while transaminase inhibition results from nonoxidative acetaldehyde metabolism. When 100-200 mumol/l acetaldehyde is added to lysates at 2-h intervals and when lysates are incubated with ethanol, alcohol dehydrogenase and an NAD-regenerating system, enzyme inhibition occurs at acetaldehyde levels approaching those seen in vivo. Thus, the role of acetaldehyde-mediated enzyme inhibition in the toxicity of alcohol abuse warrants further study.
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PMID:Effects of acetaldehyde on human red cell metabolism: evidence for the formation of enzyme inhibitors. 341 86

We applied the technique of isoelectric focusing (IEF) on immobilized pH gradients (LKB) to determine whether acetaldehyde-modified hemoglobins (Hb) prepared in vitro with unphysiological acetaldehyde concentrations have clinical relevance. This technique separates proteins with pl less than 0.01 and provides detail about hemoglobins not otherwise separable. We performed two kinds of studies. In one kind of study, we incubated red cells from control subjects with acetaldehyde. Products of these incubations were applied to IEF gels either directly or after reduction with sodium cyanoborohydride. Incubation of red cells with acetaldehyde in 1-150 mM concentration without cyanoborohydride reduction yielded hemoglobin bands of decreasing pl the appearance of which coincided with the disappearance of Hb A and Hb A1c. When the products of incubation were reduced with cyanoborohydride before IEF, an additional acidic Hb band appeared which we call the "anodal CNBH band." In a second kind of study, we compared IEF patterns of hemolysates from control subjects and alcoholism detoxification patients, without adding acetaldehyde. Again, samples were applied to IEF gels either directly or after reduction with cyanoborohydride. When samples were run on IEF without reduction, no differences were seen between patients and controls. When samples were reduced before IEF, an anodal CNBH band appeared having the same mobility as the band seen after in vitro incubations with acetaldehyde. These bands were often stronger in samples from patients, but not consistently so. Several experiments, including the use of glycolysis inhibitors, indicated that the anodal CNBH band is an adduct of fructose 1,6-diphosphate with hemoglobin. We suggest that in millimolar concentrations, acetaldehyde may function as an inhibitor of glycolysis at or below the aldolase step.
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PMID:Application of isoelectric focusing in immobilized pH gradients to the study of acetaldehyde-modified hemoglobin. 352 56

A new metabolic reaction of the aldolase condensation between formic acid and acetaldehyde proceeding with the formation of milk acid is detected in the liver of rats. Milk acid has been determined by chemical, enzymic and autoradiographic methods. Homogeneous preparations of the enzyme which catalyzes the mentioned reactions and is called lactate synthase are obtained in the crystalline form. The method for obtaining the lactate synthase from the rat liver is described as well as certain properties of the lactate synthase.
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PMID:[Various metabolic reactions of formate in animal tissues]. 362 27


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