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)

The interactions of the phosphorylated derivatives of hydroquinone (HQN-P2), resorcinol (RSN-P2), 4-hydroxybenzaldehyde (HBA-P) and 2, 4-dihydroxybenzaldehyde (DHBA-P; phosphate group at position 4) with fructose bisphosphate aldolase were analysed by enzyme kinetics, UV/visible difference spectroscopy and site-directed mutagenesis. Enzyme activity was competitively inhibited in the presence of HQN-P2, RSN-P2 and HBA-P, whereas DHBA-P exhibited slow-binding inhibition. Inhibition by DHBA-P involved active-site Schiff-base formation and required a phenol group ortho to the aldehyde moiety. Rates of enzyme inactivation and of Schiff-base formation by DHBA-P were identical, and corresponded to 3.2-3.5 DHBA-P molecules covalently bound per aldolase tetramer at maximal inactivation. Site-directed mutagenesis of the active-site lysine residues at positions 107, 146 and 229 was found to be consistent with Schiff-base formation between DHBA-P and Lys-146, and this was promoted by Lys-229. Mutation of Glu-187, located vicinally between Lys-146 and Lys-229 in the active site, perturbed the rate of Schiff-base formation, suggesting a functional role for Glu-187 in Schiff-base formation and stabilization. The decreased cleavage activity of the active-site mutants towards fructose 1, 6-bisphosphate is consistent with a proton-transfer mechanism involving Lys-229, Glu-187 and Lys-146.
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PMID:Inhibition of rabbit muscle aldolase by phosphorylated aromatic compounds. 917 4

Proglycosyn and resorcinol stimulate glycogen synthesis and inhibit glycolysis in hepatocytes. The former effect is attributed to inactivation of phosphorylase mediated by glucuronidated metabolites. This study investigated the mechanism by which resorcinol inhibits glycolysis. Resorcinol (150 microM) inhibited glycolysis in hepatocytes incubated with glucose (15-35 mM) but not with dihydroxyacetone (10 mM). The inhibition of glycolysis at elevated glucose concentration was associated with inhibition of glucose-induced dissociation of glucokinase and aldolase. The resorcinol concentration that caused half-maximal inhibition (20-43 microM) increased with increasing glucose concentration (15-35 mM). Resorcinol inhibited the translocation of glucokinase and the stimulation of detritiation of [2-3H]glucose and [3-3H]glucose caused by sorbitol (10-200 microM), but it potentiated the stimulation of glycogen synthesis. The inhibition of glycolysis by resorcinol could not be accounted for by diversion of substrate to glycogen. The glucose 6-phosphate content correlated with the free glucokinase activity. Resorcinol counteracted the increase in glucose 6-phosphate and fructose 2,6-bisphosphate caused by elevated glucose concentration or by sorbitol. The suppression of glucose 6-phosphate at high glucose concentration (15-35 mM) could be explained by the low activity of free glucokinase. However, the suppression at 5 mM glucose was due in part to an independent mechanism. The effect of resorcinol on glucokinase translocation was partly counteracted by galactosamine, which suppresses UDP-glucose and inhibits glucuronide formation, and was mimicked by phenol and p-nitrophenol but not by p-nitrophenylglucuronide. It is concluded that resorcinol inhibits glycolysis at elevated glucose concentration or when stimulated by sorbitol through increased glucokinase binding. The results indicate a link between glucuronidation and glucokinase translocation.
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PMID:Involvement of glucokinase translocation in the mechanism by which resorcinol inhibits glycolysis in hepatocytes. 927 Oct 87

The Class II fructose 1,6-bisphosphate aldolase (fda, Rv0363c) from the pathogen Mycobacterium tuberculosis H37RV was subcloned in the Escherichia coli vector pT7-7 and purified to near homogeneity. The specific activity (35 U/mg) is approximately 9 times higher than previously reported for the enzyme partially purified from the pathogen. Attempts to express the enzyme with an N-terminal fusion tag yielded inactive, mostly insoluble protein. The native recombinant enzyme is zinc-dependent and has a catalytic efficiency for fructose 1,6-bisphosphate cleavage higher than most Class II aldolases characterized to date. The aldolase has a Km of 20 microM, a kcat of 21 s(-1), and a pH optimum of 7.8. The molecular mass of the enzyme subunits as determined by mass spectrometry is in agreement with the mass calculated on the basis of its gene sequence minus the terminal methionine, 36,413 Da. The enzyme is a homotetramer and retains only two zinc ions per tetramer when transferred to a metal-free buffer, as determined by ICP-MS and by a colorimetric assay using 4-(2-pyridylazo)-resorcinol (PAR) as a chelator. The E. coli expression system reported in this study will facilitate the further characterization of this enzyme and the screening for potential inhibitors.
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PMID:Molecular cloning, expression, purification, and characterization of fructose 1,6-bisphosphate aldolase from Mycobacterium tuberculosis--a novel Class II A tetramer. 1529 2