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:3.1.1.8 (cholinesterase)
12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rare H-variant of human butyrylcholinesterase is a quantitative variant that reduces serum butyrylcholinesterase activity by about 90%. Individuals who are heterozygous for both the H-variant and the atypical variant are abnormally sensitive to the muscle relaxant succinylcholine. By using standard phenotypic serum assays, the Danish Cholinesterase Research Unit identified four individuals from two unrelated pedigrees who were heterozygous for both the H-variant (H) and the atypical (A) variant. DNA of these A/H individuals was extracted from white blood cells. Using the polymerase chain reaction and subsequent DNA sequencing, a point mutation was found at nucleotide 424 which changed amino acid 142 from valine to methionine. The previously identified atypical mutation, Asp 70 to Gly, was also seen, which segregated apart from the H-variant mutation in family studies. These two mutations were found in all four A/H individuals.
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PMID:Structural basis of the butyrylcholinesterase H-variant segregating in two Danish families. 130 23

The J-variant of human serum butyrylcholinesterase (BChE) causes both an approximately two-thirds reduction of circulating enzyme molecules and a corresponding decrease in the level of BChE activity present in serum. Since the level of serum BChE activity and the duration of succinylcholine apnea are inversely correlated, this marked decrease in activity makes individuals with the J-variant more susceptible than usual subjects to prolonged apnea from succinylcholine. We reinvestigated the same family in which Garry et al. identified the J-variant phenotype. The atypical, fluoride, and K-variant mutations were also identified in members of the 47-person pedigree. DNA amplification by PCR, followed by direct sequencing of the amplified DNA, led to the finding that the J-variant phenotype of human serum BChE was associated with two DNA point mutations in the coding region. One of these was the mutation previously identified with the K-variant phenotype (GCA----ACA; Ala539----Thr). The other was an adenine-to-thymine transversion at nucleotide 1490, which changed amino acid 497 from glutamic acid to valine (GAA----GTA; Glu497----Val). This latter point mutation was named the J-variant mutation (formal name BCHE*497V). The J-variant mutation has not been identified without the K-variant mutation. The J-variant mutation created an RsaI-enzyme RFLP. Two additional point mutations, located in the noncoding regions of the gene, were also found to be linked with the J-variant and K-variant point mutations on the same allele. These noncoding polymorphic mutations had previously been found linked to the atypical and K-variant point mutations. A summary table shows dibucaine, fluoride, and Hoffmann-La Roche compound Ro 2-0683 inhibition numbers for 119 samples whose DNA has been sequenced. Eighteen BChE genotypes are represented.
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PMID:DNA mutations associated with the human butyrylcholinesterase J-variant. 134 96

Torpedo acetylcholinesterase (AcChoEase, EC 3.1.1.7) and human butyrylcholinesterase (BtChoEase, EC 3.1.1.8), while clearly differing in substrate specificity and sensitivity to inhibitors, possess 53% sequence homology; this permitted modeling human BtChoEase on the basis of the three-dimensional structure of Torpedo AcChoEase. The modeled BtChoEase structure closely resembled that of AcChoEase in overall features. However, six conserved aromatic residues that line the active-site gorge, which is a prominent feature of the AcChoEase structure, are absent in BtChoEase. Modeling showed that two such residues, Phe-288 and Phe-290, replaced by leucine and valine, respectively, in BtChoEase, may prevent entrance of butyrylcholine into the acyl-binding pocket. Their mutation to leucine and valine in AcChoEase, by site-directed mutagenesis, produced a double mutant that hydrolyzed butyrylthiocholine almost as well as acetylthiocholine. The mutated enzyme was also inhibited well by the bulky, BtChoEase-selective organophosphate inhibitor (tetraisopropylpyrophosphoramide, iso-OMPA). Trp-279, at the entrance of the active-site gorge in AcChoEase, is absent in BtChoEase. Modeling designated it as part of the "peripheral" anionic site, which is lacking in BtChoEase. The mutant W279A displayed strongly reduced inhibition by the peripheral site-specific ligand propidium relative to wild-type Torpedo AcChoEase, whereas inhibition by the catalytic-site inhibitor edrophonium was unaffected.
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PMID:Conversion of acetylcholinesterase to butyrylcholinesterase: modeling and mutagenesis. 143 84

Nutritional status, assessed by anthropometric and biochemical methods, and muscle water, protein and amino acid composition, were evaluated in a control group of 10 children with normal renal function who were undergoing elective surgery, and in 15 children with end-stage chronic renal failure. Samples of the rectus abdominis muscle were taken when surgery was performed in the control children and when a peritoneal catheter was implanted in the uremic children. Height and body weight were reduced in the uremic children compared to the controls but skinfold thickness, arm muscle circumference and serum proteins (total protein, albumin, transferrin, pseudocholinesterase) were essentially normal. The muscle contents of total, extracellular and intracellular water, and of alkali-soluble protein (ASP), DNA and the ASP-DNA ratio were not significantly different in uremic children from those in the controls. Plasma leucine, isoleucine, tyrosine, valine, and serine levels were significantly decreased, whereas plasma citrulline, 1-methylhistidine and 3-methylhistidine levels were increased. Muscle isoleucine and valine levels and the valine/glycine ratio were low in the uremic children. Our results demonstrate that children with chronic renal failure and growth retardation may maintain a satisfactory nutritional status but exhibit amino acid abnormalities typical of uremia.
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PMID:Nutritional status and muscle amino acids in children with end-stage renal failure. 151 82

The distribution of amino acids between plasma, liver and brain was studied in adult male rats, fed a diet containing 8.7, 17 (control animals), 32 and 51% of protein during 15 days. The caloric intake was nearly equal in all groups. The highest food intake was observed in the animals on the low protein diet. Changes in plasma amino acids were variable. In contrast to the behavior of most amino acids in plasma, the branched chain amino acids were highest in the animals fed the 51% protein diet. Despite the low protein intake in the animals fed a 8.7% protein diet, the concentration of serine, glutamic acid, glutamine, glycine, alanine, methionine, isoleucine, leucine, phenylalanine and ornithine were significantly higher compared to control animals, whereas in those receiving a high protein diet, valine, leucine, tyrosine, tryptophan and histidine increased in relation to the increased protein and amino acid intake. The plasma amino acid patterns are not greatly influenced by the amino acid distribution in the food and the amount ingested. Alanine aminotransferase, aspartate aminotransferase, glutamate dehydrogenase and cholinesterase showed a two- to fivefold increased activity in the liver of animals consuming a high protein diet. In the brain, the concentration of valine, leucine, isoleucine, phenylalanine and tyrosine in animals receiving the low protein diet was higher than in controls and increased further with increasing protein content of the diet. Glutamine was increased in all dietary groups. The predicted influx of amino acids showed increasing influx rates in dependence of the plasma amino acid concentration. The entry of tyrosine and tryptophan and their brain concentration was inversely proportional to the protein content of the diet. In the present study which considers long-term adaptation to an increasing protein and amino acid intake in comparison to a balanced control protein diet, the levels of the indispensable amino acids were maintained within narrow limits in the brain and liver. The results indicate that inspite of a variable protein intake, the body tends to keep organ amino acids in relatively narrow limits favoring in this way amino acid homeostasis.
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PMID:Effect of different protein diets on the distribution of amino acids in plasma, liver and brain in the rat. 159 Jun 69

The cholinesterases are serine hydrolases that show no global similarities in sequence with either the trypsin or the subtilisin family of serine proteases. The cholinesterase superfamily includes several esterases with distinct functions and other proteins devoid of the catalytic serine and known esterase activity. To identify the residues involved in catalysis and conferring specificity on the enzyme, we have expressed wild-type Torpedo acetylcholinesterase (EC 3.1.1.7) and several site-directed mutants in a heterologous system. Mutation of serine-200 to cysteine results in diminished activity, while its mutation to valine abolishes detectable activity. Two conserved histidines can be identified at positions 425 and 440 in the cholinesterase family; glutamine replacement at position 440 eliminates activity whereas the mutation at 425 reduces activity only slightly. The assignment of the catalytic histidine to position 440 defines a rank ordering of catalytic residues in cholinesterases distinct from trypsin and subtilisin and suggests a convergence of a catalytic triad to form a third, distinct family of serine hydrolases. Mutation of glutamate-199 to glutamine yields an enzyme with a higher Km and without the substrate-inhibition behavior characteristic of acetylcholinesterase. Hence, modification of the acidic amino acid adjacent to the serine influences substrate association and the capacity of a second substrate molecule to affect catalysis.
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PMID:Mutagenesis of essential functional residues in acetylcholinesterase. 221 85

Our laboratory has recently shown that several variant forms of human butyrylcholinesterase, associated with unusual sensitivity to succinylcholine, are caused by specific mutations within the structural DNA coding for this enzyme. Atypical (dibucaine-resistant) butyrylcholinesterase is caused by a point mutation at nucleotide position 209(GAT-- greater than GGT), which changes aspartate 70 to glycine. One fluoride-resistant variant family has a point mutation at nucleotide 728(ACG-- greater than ATG), which changes threonine 243 to methionine. Another type of fluoride-resistant variant has a point mutation at nucleotide 1169(GGT-- greater than GTT), which changes glycine 390 to valine. One type of silent phenotype is due to a frame-shift mutation at nucleotide position 351(GGT-- greater than GGAG). A polymorphic site at nucleotide position 1615 (GCA/ACA), coding for Ala/Thr, accounts for the quantitative K-variant, which causes an approximate one-third reduction of activity, if Thr occupies that position at codon 539. Examples are given to illustrate the advantages of using a combination of the new DNA analytical techniques, including: the use of allele-specific probes, with the standard serum cholinesterase phenotyping methods. More accurate typing of patients with certain variants is now possible; pedigree analysis will be aided by the improved methodology.
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PMID:Phenotypic and molecular biological analysis of human butyrylcholinesterase variants. 225 36

Male Sprague-Dawley rats daily treated with DFP (0.5 mg/kg/day, sc) exhibited signs of cholinergic toxicity such as tremors and muscle fasciculations between Days 3 and 5 comparable to those observed 15 min after a single acute signs-producing dose (1.5 mg/kg, sc). Further administration of DFP (0.5 mg/kg/day, sc) for 6-14 days led to tolerance development as evidenced by disappearance of the described toxicity signs. The protein synthesis inhibitor cycloheximide, when given in a nontoxic dose (0.5 mg/kg/day, sc) 1 hr before DFP (0.5 mg/kg/day, sc) administration, potentiated the DFP toxicity and rats died after the fifth injection. DFP-tolerant rats developed toxicity signs when subsequently treated with cycloheximide (0.5 mg/kg/day, sc) and DFP (0.5 mg/kg/day, sc). Each drug when given alone for 4 days caused 30-50% reduction of [14C]valine uptake in vivo into the free amino acids pool as well as its incorporation into proteins of brain and skeletal muscles. A combination of these drugs caused a significantly greater inhibitory effect on [14C]valine incorporation into proteins. Cycloheximide (0.5 mg/kg/day, sc) administered for 4 days did not significantly alter the levels of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), or carboxylesterase (CarbE) activities but potentiated the DFP-induced inhibition of the activities of these enzymes. It is concluded that the cycloheximide pretreatment potentiates DFP toxicity by a mechanism that is related to inhibition of the synthesis of proteins such as AChE, BuChE, and CarbE.
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PMID:Interaction of cycloheximide and diisopropylphosphorofluoridate (DFP) during subchronic administration in rat. 362 91

Nine esterase fractions hydrolyzing 1-naphthylacetate were revealed in Triton X-100-solubilized extracts from aphides homogenates by polyacrylamide gel electrophoresis. The less mobile fractions 1-4 were identified as cholinesterases, using specific inhibitors--eserine and the cationic phosphoorganic inhibitor Gd-42; fractions 5-7 were related to carboxylesterases, using specific inhibition by triorthocresylphosphate and O,O-dimethyl (2,2-dichlorvinyl)phosphate. The most mobile fractions 8-9 which were resistant to the inhibitors, were classified as arylesterases. The aphis cholinesterase fractions revealed the highest mobility; the activity of carboxylesterase fractions was lower. Thiophosphonate--C8H17O(CH3)P(O)-SCH2SCH2COOCH3 was found to be a highly efficient selective inhibitor of aphis carboxylesterase, i. e. the kII values for carboxylesterase and cholinesterase were equal to 10(8) and 10(5) M-1 min-1, respectively. The thiophosphoorganic derivatives containing a beta-alanine residue in the cleaved part are more specific to acetylcholinesterase and carboxylesterase than those containing a valine residue. Studies with enanthiomers--C2H5O(CH3)P(O)SCH2CONHCH2CH2COOC2H5 and (C2H5O)2P(O)SCH2CONHCH(iC3H7)COOC2H5 have demonstrated that the asymmetry due to the central phosphorus atom is more essential for the acetylcholinesterase and carboxylesterase activities than that connected with the carbon atom in the cleaved part of the inhibitor molecule. During the interaction of the enanthiomers with the asymmetric phosphorus the stereospecificity of acetylcholinesterase is much higher than that of carboxylesterase. In terms of stereospecificity of the esterase site aphis acetylcholinesterase is is similar to its mammalian counterpart, while carboxylesterase from the same source is rather close to mammalian butyrylcholinesterase.
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PMID:[Multiple molecular forms of esterases from grass aphids inhibitory identification and stereospecificity]. 663 87

Cognitive impairment in schizophrenia occurs in the early phases of the disease and remains throughout its course. The basis for cognition lies in two main brain regions: the prefrontal cortex and hippocampus. Positron emission tomography, functional magnetic resonance imaging, and proton magnetic spectroscopy studies have shown that prefrontal cortex and hippocampus activity and cell density are lower in patients with schizophrenia than in healthy controls. Dopamine remains the fundamental neurotransmitter involved with schizophrenia. Catechol- O -methyltransferase accounts for about 60% of dopamine metabolism in the prefrontal cortex. Functional polymorphism for the catechol- O -methyltransferase genotypes has been identified in patients with schizophrenia. Those with the valine-valine genotype demonstrate rapid inactivation of dopamine, and performance in cognitive testing in patients is poorer with this allele than with other genotypes. N -methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate acid receptors are also strongly associated with cognitive impairment. Changes occur in apolipoproteins D and E, cholinesterase enzyme activity, neurotensin, and neural growth factors, leading to a possible neurodegenerative process and cognitive impairment in patients with schizophrenia. A fundamental link between psychosis and neurocognition probably arises from complex interactions between these systems at the intracellular secondary messenger system and with protein phosphorylation. Atypical antipsychotics evaluated in receptor models, cell cultures, and animal behavior paradigms indicate that these agents may provide neuroprotective effects. Clinical studies with atypical antipsychotics have consistently demonstrated improvement in cognitive symptoms, and such improvement appears to be correlated with improvement of negative symptoms. A neurodevelopmental model of cognitive impairment in schizophrenia aids in understanding why atypical antipsychotics improve cognitive symptoms.
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PMID:Implications for atypical antipsychotics in the treatment of schizophrenia: neurocognition effects and a neuroprotective hypothesis. 1558 43


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