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)

Chemical analysis of enzyme reaction intermediates has been used to compare the liver and muscle isozymes of rabbit aldolase at equilibrium and in their steady states to determine if they have properties that favor the direction of flow of glycolytic intermediates in their tissues of origin. For both enzymes at saturating concentrations of fructose 1,6-P2, the sum of intermediates in the steady state agreed with the total active enzyme calculated to be present. The two half-reactions, characterized by fructose 1,6-bisphosphate(Fru-P2):aldehyde exchange and DHAP:proton exchange were found to be of different importance in determining the rate of reaction with Fru-P2 with the liver enzyme being much more limited in the processing of DHAP. The chemical interconversions within each half-reaction are generally rapid compared with the release of products. The greater sensitivity of liver aldolase to inhibition by aldehydes in Fru-P2 cleavage seems to be a normal consequence of the higher level of the eneamine of DHAP in the forward steady state with the liver enzyme and probably should not be ascribed to a greater intrinsic affinity. An earlier report (Grazi, E., and Trombetta, G. (1979) Eur. J. Biochem. 100, 197-202) purporting to show a special interaction of glyceraldehyde-3-P with liver enzyme prior to proton abstraction from DHAP could not be reproduced. Examples are presented from the data that validate the use of the analytical methods used for analysis of intermediates in the case of the Schiff's base aldolases.
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PMID:Concentration and partitioning of intermediates in the fructose bisphosphate aldolase reaction. Comparison of the muscle and liver enzymes. 380 4

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

Isotopic and enzymic evidence indicates that Zymomonas anaerobia ferments glucose via the Entner-Doudoroff pathway. The molar growth yields with glucose (5.89) and fructose (5.0) are lower than those for the related organism Zymomonas mobilis and the observed linear growth suggests that energetically uncoupled growth occurs. A survey of enzymes of carbohydrate metabolism revealed the presence of weak phosphofructokinase and fructose 1,6-diphosphate aldolase activities but phosphoketolase, transketolase and transaldolase were not detected. Fermentation balances for glucose and fructose are reported; acetaldehyde accumulated in both fermentations, to a greater extent with fructose which also yielded glycerol and dihydroxyacetone as minor products.
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PMID:Glucose and fructose metabolism in Zymomonas anaerobia. 425 36

A study was made of the regulation of three enzymes that act sequentially in the metabolism of thymidine in Escherichia coli K-12. Under a variety of conditions, two of the enzymes, thymidine phosphorylase and deoxyribose-5-phosphate aldolase, were found to be synthesized coordinately. However, the third enzyme, phosphodeoxyribomutase, was synthesized noncoordinately with the other two enzymes under the same conditions. In addition, the mutase could be fully induced, whereas basal levels of the phosphorylase and the aldolase were maintained. These findings indicate that two operons comprise the genes concerned with the reversible pathway leading from thymidine to acetaldehyde and glyceraldehyde-3-phosphate. In addition to thymidine, it was found that acetaldehyde was an external inducer of these enzymes. The results of induction experiments performed on wild-type cells and mutants defective in the mutase or the aldolase, with thymidine or acetaldehyde as exogenous inducers, strongly suggest that deoxyribose-5-phosphate is more proximal to the intracellular inducer than is thymidine, deoxyribose-1-phosphate, or acetaldehyde.
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PMID:Regulation of thymidine metabolism in Escherichia coli K-12: studies on the inducer and the coordinateness of induction of the enzymes. 493 66

Pyridoxal phosphate can act as a specific photosensitizer for amino acid residues in rabbit muscle and spinach leaf aldolases, but the residues affected depend on the pH of the reaction. Below pH 8 one histidine residue per enzyme subunit is destroyed; above pH 8.5 there is little loss of histidine, and photoinactivation is associated with the destruction of specific tyrosine residues, particularly the COOH-terminal residues. Pyridoxal and 4-pyridinecarboxaldehyde are much less effective than pyridoxal phosphate at neutral pH, but are similar to pyridoxal phosphate in their photosensitizing activity at the higher pH. Compounds lacking the aldehyde group or the pyridine ring show little or no activity. A number of other enzymes, including alpha-glycerophosphate dehydrogenase, glucose-6-phosphate dehydrogenase, and yeast hexokinase, were also photoinactivated in the presence of pyridoxal phosphate; however, rabbit liver aldolase and two isomerases tested were completely resistant. The results suggest that certain enzymes, including rabbit muscle and spinach aldolases, but not rabbit liver aldolase, contain a specific site which interacts with pyridoxal phosphate, and that the conformation of this site changes in the pH range between 8.0 and 8.5
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PMID:Photoinactivation of aldolases by pyridoxal phosphate and its analogues. 527 95

In Bacillus cereus purine ribonucleosides and deoxyribonucleosides share a common inducible catabolic pathway, leading to the formation of ribose-5-P or deoxyribose-5-P respectively inside the cell, while the purine ring remains in the external medium. Both ribo- and deoxyribonucleosides are inducers of adenosine deaminase, inosine-guanosine phosphorylase and phosphopentomutase, the enzymes of the catabolic pathway. We now show that deoxyribonucleosides, but not ribonucleosides, induce the aldolase specific for deoxyribose-5-P (2-deoxy-D-ribose-5-phosphate acetaldehyde lyase, EC 4.1.2.4), thus allowing the sugar moiety of exogenous deoxyribonucleosides to be utilized as an energy source.
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PMID:Induction of deoxyribose-5-phosphate aldolase of Bacillus cereus by deoxyribonucleosides. 643 5

The equivalence of the four dihydroxyacetone phosphate binding sites of aldolase was abolished by lowering the temperature. At pH 6.2 and -13 degrees C, four binding sites were detected by gel filtration; two sites with a Kdiss less than or equal to 0.1 microM, and a second set of sites with a Kdiss = 4 microM. The alteration of the binding was accompanied by the alteration of the catalytic activity. The low-affinity sites were incapable of catalyzing the cleavage of the (3S) C-H bond of dihydroxyacetone phosphate, and form only the ketimine phosphate intermediate. The high-affinity sites were still able to cleave the (3S) C-H bond of dihydroxyacetone phosphate; however, the eneamine phosphate intermediate formed was almost fully converted into the eneamine-aldehyde . . . phosphate intermediate, which was the prevailing species at the equilibrium. The mechanism of the half-of-the sites reactivity of aldolase at low temperature has been explained and the nonequivalence of sites in promoting catalysis has been utilized to dissect and characterize the individual partial reactions of the enzyme. In the course of these studies it has been shown that the rate of hydration-dehydration of dihydroxyacetone phosphate at -24 degrees C was too slow to measure.
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PMID:Fructose-1,6-bisphosphate aldolase from rabbit muscle: different catalytic behavior of the dihydroxyacetone phosphate binding sites at low temperature. 648 3

Hemoglobin A1 (HbA1) levels were significantly higher in healthy alcohol drinkers (HbA1 = 7.50%, n = 11) than in normal non-drinkers (HbA1 = 6.62%, n = 13). Ethanol was not able to change HbA1 level when ethanol was added to human whole blood in vitro. Acetaldehyde (AcCHO), although, markedly increased it. Glucose utilization in erythrocytes was stimulated by AcCHO. While it was completely blocked by sodium fluoride in the presence of AcCHO in the incubation medium, but sodium fluoride did not affect the formation of HbA1. AcCHO formed HbA1 with human purified hemoglobin in vitro. The level of HbA1 formed by AcCHO was significantly low when purified human hemoglobin used as a substrate in comparison with the use of whole blood. AcCHO and dihydroxyacetone phosphate reacted in the presence of aldolase. The reacted product, 5-deoxy-D-xylulose-1-phosphate, increased HhA1 level of human purified hemoglobin. It is suggested, the high level of HbA1 in healthy drinkers was caused by AcCHO, the first metabolite of ethanol. AcCHO formed addicts with human hemoglobin directly, and there might be other mechanisms of HbA1 formation due to AcCHO, such as 5-deoxy-D-xylulose-1-phosphate, which is the reacted product of AcCHO.
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PMID:[Mechanisms of high hemoglobin A1 in alcohol drinkers]. 651 Aug 86

At or below -12 degrees C and in the presence of 40% ethylene glycol, only two out of the four dihydroxyacetone phosphate binding sites of aldolase are catalytically active. At these same temperatures and at pH* 8.3, the equilibrium between the pre-enamine and the enamine plus the post-enamine intermediates is largely shifted in favor of the latter. The enamine phosphate and the enamine-aldehyde phosphate intermediates have been resolved by studying the rate of their formation at -13 degrees C and pH* 5.28 and the trapping by DL-glyceraldehyde 3-phosphate at -24 degrees C and pH* 5.24.
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PMID:Fructose-1,6-bisphosphate aldolase from rabbit muscle. Kinetic resolution of the enamine phosphate from the enamine-aldehyde intermediate at low temperature. 662 9

The biosynthesis of carnitine proceeds from trimethyllysine (TML) by beta-hydroxylation by a liver or kidney mitochondrial enzyme, which requires oxygen, alpha-ketoglutarate, ferrous iron, and ascorbate. This dioxygenase is rapidly inactivated by preincubation with Fe2+, but not Fe3+. The evidence suggests that superoxide anion is involved in the hydroxylation. beta-Hydroxytrimethyllysine undergoes aldol cleavage to glycine and trimethylaminobutyraldehyde under the influence of serine hydroxymethyltransferase and possibly a specific aldolase. The next step, the aldehyde oxidation, is catalyzed by a specific NAD-dependent aldehyde dehydrogenase from liver cytosol. The product, trimethylaminobutyrate, is then hydroxylated by a cytosolic dioxygenase to carnitine. This enzyme, which has the same cofactor requirements as TML hydroxylase, is found in the liver of all species examined, but is absent from the kidney of some species.
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PMID:Mammalian enzymes of trimethyllysine conversion to trimethylaminobutyrate. 681 45


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