Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of hamster liver passage on the isoenzyme patterns of isolates of Entamoeba histolytica was investigated. Three isolates, F, G and T were originally obtained from patients with acute amebic dysentery and another strain, C, was obtained from an asymptomatic carrier. All these strains were maintained for over two years in axenic culture. The isoenzyme pattern (zymodeme) of hexokinase (HK), phosphoglucomutase (PGM) and glucose phosphoisomerase (GPI) of these strains was found to belong to non-pathogenic group X, but the isoenzyme pattern of GPI resembled less pathogenic zymodeme XX and might be an intermediate type. Following inoculation of trophozoites into hamster livers and recovery after abscess formation, their isoenzyme pattern changed and revealed that they belonged to pathogenic type XIV. Liver passage caused an enhancement in amebic virulence as evidenced by their increased ability to destroy leukocytes. The results indicate that isoenzyme pattern is not a stable property of E. histolytica.
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PMID:Effect of hamster liver passage on the isoenzyme patterns of Entamoeba histolytica. 130 61

Using agarose gel electrophoresis, the electrophoretic patterns of four enzymes: malate NADP oxidoreductase (malic enzyme) (ME), glucosephosphate isomerase (GPI), phosphoglucomutase (PGM) and hexokinase (HK), were compared and analysed for five strains of Entamoeba histolytica, which had been obtained from patients with acute amebic dysentery or asymptomatic cyst carrier in Beijing, Tianjin and Fujian Province. The results showed that the electrophoretic patterns of all the five strains of E. histolytica belong to pathogenic zymodeme, zymodeme XIV, which is suggested to be the main pathogenic zymodeme in our country.
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PMID:[Distribution of zymodemes of Entamoeba histolytica from different areas of China]. 182 58

Entamoeba histolytica is responsible for amoebic colitis and liver abscess in humans. Entamoeba dispar is a closely related, morphologically indistinguishable nonpathogenic species. The hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) isoenzyme patterns distinguish the pathogenic and nonpathogenic species. Both species possess two hexokinases with very similar molecular mass and different isoelectric points. In order to understand the role of the two different isoenzymes from E. histolytica, we purified the recombinant hexokinases HXK1 and HXK2 and examined substrate spectrum and kinetic properties. The two enzymes displayed similar temperature and pH optima, they were inhibited strongly by AMP and ADP, not by glucose 6-phosphate. Both enzymes phosphorylated glucose well and were unable to phosphorylate fructose or galactose. We also detected significant differences. HXK1 was more sensitive to inhibition by AMP and ADP. Mannose was phosphorylated well by HXK1, but at a much lower rate by HXK2. We attempted to expand the substrate spectrum of E. histolytica HXK1 by modifying its active site to become similar to the active site of the fructose phosphorylating yeast hexokinase PII. None of the nine mutants gained any fructokinase activity, but all of them retained at least some glucokinase and mannokinase activity. Mannokinase activity was decreased drastically by two single amino acid exchanges, both of which contributed significantly to this effect. The data indicate that a complex interaction of a number of amino acid residues is necessary for the ability to phosphorylate a given hexose.
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PMID:Differences in substrate specificity and kinetic properties of the recombinant hexokinases HXK1 and HXK2 from Entamoeba histolytica. 1061

Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila. An acetate kinase which can only utilize PP(i) but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD(+) by the enzymes pyruvate kinase and lactate dehydrogenase, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP(+) to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PP(i).
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PMID:Direct detection of the acetate-forming activity of the enzyme acetate kinase. 2221 84