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)

Among 56 persons studied, 6 were heterozygous with respect to the elongated variant of the Band 3 protein (anion transporting protein) of the erythrocyte membranes. Erythrocytes containing the variant Band 3 protein did not exhibit morphologic abnormalities, alterations in electron spin resonance spectra of maleimide-spin labeled membranes. In the rate of membrane 'self-digestion' or in chloride permeability. They did however show an increased membrane binding of hemoglobin and aldolase.
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PMID:Consequences of the presence of elongated variant of the major transmembrane protein (Band 3 protein) in the human erythrocyte. 165 53

When assayed in vitro, the activity of the photosynthetic enzyme ribulose 1,5 bisphosphate carboxylase oxygenase is both enhanced and protected from spontaneous decay by exogenous proteins such as hemoglobin, serum albumin, and aldolase. Other proteins and amino acids tested are either ineffective (lysozyme, ferritin, lysine, and cysteine) or afford only partial protection (catalase, glycine, and phenylalanine). Protective proteins do not bind to, or exchange disulfides with, ribulose 1.5 bisphosphate carboxylase/oxygenase. Since their effect can be mimicked by reductively treated detergents such as Triton X-100, it appears that proteins protect from decay by quenching the spontaneous oxidative degradation and inhibiting surface adsorption which could lead to enzyme unfolding. Release of adsorbed molecules from the container surface is likely to be the cause of carboxylase activity enhancement.
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PMID:Protection and enhancement of ribulose 1,5 bisphosphate carboxylase activity by exogenous proteins. 191 Apr 60

The inhibition of rat hepatic glutathione (GSH) S-transferase 1-2 by bilirubin exhibited pseudo first-order kinetics with k(obs) values of 0.0214 +/- 0.0005 and 0.040 +/- 0.008 sec-1 at 4 and 8 microM bilirubin, when followed to 72 and 84% completion respectively. These correspond to calculated second-order rate constants of 5.3 +/- 0.1 x 10(3) and 5.0 +/- 1.0 x 10(3)/M.sec. The extent of inhibition of the transferase increased with bilirubin concentration, with half-maximal inhibition at 4 microM bilirubin. Inhibition was reversed by 10-fold dilution of bilirubin or by increasing the pH from 6.0 to 7.4. Premixing 0.2 to 0.5 microM albumin, hemoglobin or aldolase with bilirubin prevented inhibition of GSH S-transferase 1-2. Protection by these proteins occurred at a selected high concentration (0.2 to 0.4 microM) at which they reduced free bilirubin to concentrations (less than 0.5 microM) that did not inhibit isoenzyme 1-2 significantly. No protection was afforded by a selected low protein concentration (0.001 to 0.01 microM) which did not strikingly reduce bilirubin levels in solution. We conclude that bilirubin inhibition of GSH S-transferase 1-2 appears to be a second-order process; the reaction is clearly first-order with respect to GSH S-transferase and appears also to be first-order with respect to bilirubin. It is proposed that (a) inhibition of GSH S-transferase 1-2 results from slow, reversible bilirubin binding, and (b) added proteins appear to prevent GSH S-transferase inhibition by binding high molar ratios of bilirubin.
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PMID:Reversible inhibition of rat hepatic glutathione S-transferase 1-2 by bilirubin. 222 11

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

The cytoplasmic domain of band 3 (cdb3) of the human erythrocyte membrane is a good substrate of endogenous and exogenous protein-tyrosine kinases. Because one site of tyrosine phosphorylation is within the glycolytic enzyme/hemoglobin-binding region at the N terminus of the polypeptide, we have investigated whether tyrosine phosphorylation of cdb3 might influence its interaction with the above peripheral proteins. Using p40, a protein-tyrosine kinase isolated from bovine thymus, we demonstrate that aldolase binding to cdb3 linked to Affi-Gel 15 is significantly inhibited by phosphorylation of the immobilized band 3. Importantly, upon dephosphorylation of the gel with acid phosphatase, aldolase binding returns to prephosphorylated values. Similarly, cdb3 phosphorylation was found to inhibit glyceraldehyde-3-phosphate dehydrogenase, phosphofructokinase, and hemoglobin binding to immobilized cdb3. In the converse experiment, untreated soluble cdb3 was shown to bind to immobilized aldolase, whereas phosphorylated cdb3 (approximately equal to 1.8 mol of Pi/mol of cdb3) did not. Furthermore, phosphorylated cdb3 was unable to inhibit aldolase catalysis, whereas untreated cdb3, as shown previously by others, was a potent inhibitor. Taken together, these results demonstrate that phosphorylation of cdb3 on tyrosine residues inhibits peripheral protein binding at the polypeptide's N terminus. In view of the known effect of glycolytic enzyme binding to band 3 on catalytic activity, tyrosine phosphorylation of band 3 may modulate glycolysis in vivo.
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PMID:Tyrosine phosphorylation of band 3 inhibits peripheral protein binding. 355 57

Models describing the interaction of a small molecule with a protein are typically couched in terms of the stoichiometry, cooperativity, and binding free-energy change. These parameters are readily available from equilibrium dialysis experiments (or appropriate variations). With the recent advent of extremely sensitive calorimeters, it is possible to obtain thermal data for the binding reaction and, thus, the entire set of thermodynamic parameters, delta G', delta H', delta S', delta C', become readily available. This review is limited to the binding of nucleotides and nucleotide analogs to proteins for which complete thermal data are available. While the majority of such systems have been characterized by calorimetry, we have not excluded, per se, van't Hoff enthalpy determinations. The systems we have considered include, but are not limited to, thymidylate synthetase, phosphorylase, several dehydrogenases, aldolase, glutamine synthetase, hemoglobin, asparate transcarbamylase, and ribonuclease. A variety of forces contribute to the total free-energy change upon ligand binding. These forces include ionic, van der Waals, hydrogen bond, and hydrophobic. In several cases, properly designed experiments have allowed a partial resolution of the individual contributions of these various forces. Variation of easily accessible conditions such as temperature, pH, ionic strength, or solvent third component produce changes in the set of thermodynamic parameters which lead to the resolution of the forces. The generality of heat effects makes this method very useful for studying the involvement of protons in binding reactions. The variation in the magnitude and direction (release or uptake) of the proton flux is readily studied by determining the apparent heat of reaction at constant pH, ionic strength, and temperature in two or more buffers of differing heat of ionization. This application has been exploited in several cases and is examined in great detail. An overview of the results in these systems to date suggests that several trends observed in the thermodynamic parameters need to be confirmed by further experimentation and, if they hold, an appropriate theoretical basis must be developed to aid in their interpretation.
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PMID:The thermodynamics of nucleotide binding to proteins. 610 94

1. Erythrocyte counts, hemoglobin concentrations and hematocrit values were determined for diploid and triploid Ctenopharyngodon idella X Hypophthalmichthys nobilis hybrids and the parental species. 2. Comparisons of diploid and triploid hybrids with the parental species revealed low erythrocyte counts for triploids, high mean corpuscular hemoglobin values for triploids, elevated hematocrits for diploids and triploids and similar hemoglobin concentrations for all fish. 3. Alkaline phosphatase, aldolase, and lactate dehydrogenase specific activities were determined spectrophotometrically. Levels of specific activity of these enzymes in the hybrids were consistently elevated above that of the parental species. These higher levels of enzyme activities in hybrids were probably the result of a breakdown in gene regulation.
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PMID:Hematologic and enzymatic analysis of Ctenopharyngodon idella x Hypophthalmichthys nobilis F1 hybrids. 613 39

The oxygen transport protein hemoglobin interacts specifically and reversibly with the red cell membrane. pH and ionic strength dependence of these interactions indicate their electrostatic nature. The anion transport protein band 3 has been implicated as the protein to which hemoglobin binds. Hemoglobin, aldolase and glyceraldehyde 3-phosphate dehydrogenase have a similar pH and ionic strength dependence in binding to 23K fragment. The three compete for the same amino-terminal 23 residue sequence region of band 3. The binding site is a highly acidic segment without any positive charge. We have recently determined the sequence of amino-terminal 23K fragment of band 3. There is a remarkable internal sequence homology between the first eleven and next eleven residues in this sequence region. Biophysical measurements in this sequence region. Biophysical measurements have revealed that 23K is a tetramer under physiological conditions. The implications of this structure of 23K is discussed with respect to the interaction of band 3 with the red cell cytoskeleton.
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PMID:Interaction of hemoglobin with band 3: a review. 635 41

Intraperitoneal administration of leupeptin to rats induced a hemoglobin-hydrolyzing protease which was most active at pH 3.5 and was insensitive to pepstatin in various tissues such as the liver, kidney, and muscle, as observed previously in adult rat hepatocytes in primary culture (Tanaka, K., Ikegaki, N., and Ichihara, A. (1979) Biochem. Biophys. Res. Commun. 91, 102-107). The induced acidic protease was purified about 600-fold in 30% yield from rat liver by conventional chromatographic techniques. The purified enzyme appeared homogeneous by polyacrylamide gel electrophoresis in the presence or absence of sodium dodecyl sulfate and was a monomeric protein of Mr = 20,000. The enzyme appeared to be a glycoprotein because its induction was blocked by the addition of tunicamycin to cultures of hepatocytes and because the induced protease was absorbed on concanavalin A-Sepharose and eluted with methylglucoside. It seemed to be present in lysosomes and was fairly stable at various pH values and temperatures. It showed endopeptidase activity on various protein substrates, but scarcely hydrolyzed N-substituted derivatives of arginine. It did not hydrolyze esters, showed no aminopeptidase or carboxypeptidase activity, and did not inactivate glucose-6-phosphate dehydrogenase or aldolase. The enzyme appeared to be a thiol protease, since it was strongly inhibited by sulfhydryl-reactive compounds and N-( [N-(1-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]-agmatine and was not inhibited by reagents specific for carboxyl-, serine-, or metalloproteases. This induced protease could be separated from cathepsins B, D, and H by chromatography. The enzyme was similar to cathepsin L in chromatographic behavior, Mr and pI, but differed from the latter in stability and in its inability to inactivate some enzymes. These results suggest that it differs from any known proteases found previously in rat liver.
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PMID:Purification and characterization of hemoglobin-hydrolyzing acidic thiol protease induced by leupeptin in rat liver. 637 Oct 12

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


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