Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the active site residue, human milk bile-salt stimulated lipase (BSSL) was labelled with [3H]diisopropyl fluorophosphate (DFP). Partial sequence analysis of cyanogen bromide fragments (a total of 146 residues from 6 peptides) revealed 84% sequence identity with a putative rat lysophospholipase. Sequence analysis of a [3H]DFP-labelled peptide indicated that the active site serine was contained in the sequence Gly-Glu-Ser-Ala-Gly. In addition to similarity with rat lysophospholipase, this sequence showed homology with regions of human butyrylcholinesterase and electric ray acetylcholinesterase (68% identity). It is concluded that these proteins are members of a new supergene family.
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PMID:Human milk bile-salt stimulated lipase. Sequence similarity with rat lysophospholipase and homology with the active site region of cholinesterases. 199 11

The histidine residue essential for the catalytic activity of pancreatic cholesterol esterase (carboxylester lipase) has been identified in this study using sequence comparison and site-specific mutagenesis techniques. In the first approach, comparison of the primary structure of rat pancreatic cholesterol esterase with that of acetylcholinesterase and cholinesterase revealed two conserved histidine residues located at positions 420 and 435. The sequence in the region around histidine 420 is quite different between the three enzymes. However, histidine 435 is located in a 22-amino acid domain that is 47% homologous with other serine esterases. Based on this sequence homology, it was hypothesized that histidine 435 is the histidine residue essential for catalytic activity of cholesterol esterase. The role of His435 in the catalytic activity of pancreatic cholesterol esterase was then studied by the site-specific mutagenesis technique. Substitution of the histidine in position 435 with glutamine, arginine, alanine, serine, or aspartic acid abolished the ability of cholesterol esterase to hydrolyze p-nitrophenyl butyrate and cholesterol [14C]oleate. In contrast, mutagenesis of the histidine residue at position 420 to glutamine had no effect on cholesterol esterase enzyme activity. The results of this study strongly suggested that histidine 435 may be a component of the catalytic triad of pancreatic cholesterol esterase.
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PMID:Site-specific mutagenesis of an essential histidine residue in pancreatic cholesterol esterase. 199 99

A peptide of acetylcholinesterase (AcChoEase; acetylcholine acetylhydrolase, EC 3.1.1.7) from the venom of the cobra Naja naja oxiana labeled by the affinity reagent N,N-dimethyl-2-phenylaziridinium (DPA) has been identified. The sequence is Gly-Ala-Glu-Met-Trp-Asn-Pro-Asn. In AcChoEase from Torpedo californica, a homologous peptide was labeled and isolated. Its sequence is Ser-Gly-Ser-Glu-Met-Trp-Asn-Pro-Asn, representing positions 79 through 87. In both cases labeling can be prevented by 0.1 mM edrophonium, indicating that the respective peptides form part of the anionic subsite of the catalytic center. The modified residue was tryptophan (Trp-84 in Torpedo AcChoEase) in both enzymes. In contrast to AcChoEase from Torpedo, the enzyme from cobra venom does not contain a peripheral anionic binding site.
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PMID:Anionic subsites of the catalytic center of acetylcholinesterase from Torpedo and from cobra venom. 206 91

The aim of our work was to assess the performance of tissue polypeptide antigen in detecting hepatocellular carcinoma in cirrhotic patients, while also checking for any influence of liver dysfunction on the serum level of the marker. One hundred and twenty-five consecutive cirrhotic patients, 35 with and 90 without, hepatocellular carcinoma were studied. Tissue polypeptide antigen had a different distribution in the two groups and the best diagnostic accuracy with 48.6% sensitivity and 85.6% specificity was found at the cut-off value of 240 UL-1. In cirrhotic patients significant linear correlations were found between tissue polypeptide antigen and alanine-transaminase, aspartate-transaminase, G-glutamyl-transpeptidase and alkaline phosphatase; there was no correlation with bilirubin or pseudo-cholinesterase. In patients with hepatocellular carcinoma a significant linear correlation was found only with alanine and aspartate transaminase and G-glutamyl-transpeptidase. The analysis of covariance still showed a significant difference between mean tissue polypeptide antigen levels in the two groups also accounting for covariates. These results suggest that: a) the liver dysfunction may be involved in increasing tissue polypeptide antigen values; b) tissue polypeptide antigen has a different distribution in cirrhotic patients with and without hepatocellular carcinoma also accounting for covariates; these findings further support the specificity of tissue polypeptide antigen.
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PMID:The serum tissue polypeptide antigen in the detection of hepatocellular carcinoma in cirrhotic patients. 217 22

The venom from Crotalus molossus nigrescens contains many activities including: hyde powder azure proteinase; N-benzoyl-arginine-ethyl-ester hydrolase; phospholipase; phosphodiesterase; desoxyribonuclease; fibrinogen coagulase; collagenase, fibrinolytic activity, and hemorrhagic factors. The venom, assayed with amounts of venom up to 50 micrograms protein per assay, does not contain acetylcholinesterase, phosphatase, amylase, ribonuclease, tyrosyl-ester hydrolase or hyaluronidase activities. The venom is lethal to mice with an i.p. LD50 of 2.35 mg/kg mouse. Fractionation of soluble venom by Sephadex G-75 separates at least five families of components. Fractions I-III contains all the enzymes, and fraction V have six small peptides. Further separation of fractions II-III on diethyl-amino-ethyl-cellulose columns at pH 8.0 and 8.3 gave pure proteinase E with a mol. wt of 21,390 and the following N-terminal amino acid sequence; Phe-Ala-Lys-Arg-Tyr-Val-Glx-Leu-Val-Ile-Val-Ala. A thrombin-like enzyme with a mol. wt of 75,000 was also purified from this venom by means of affinity and ion exchange chromatographies.
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PMID:Characterization of the venom from Crotalus molossus nigrescens Gloyd (black tail rattlesnake): isolation of two proteases. 218 98

People with genetic variants of cholinesterase respond abnormally to succinylcholine, experiencing substantial prolongation of muscle paralysis with apnea rather than the usual 2-6 min. The structure of usual cholinesterase has been determined including the complete amino acid and nucleotide sequence. This has allowed identification of altered amino acids and nucleotides. The variant most frequently found in patients who respond abnormally to succinylcholine is atypical cholinesterase, which occurs in homozygous form in 1 out of 3500 Caucasians. Atypical cholinesterase has a single substitution at nucleotide 209 which changes aspartic acid 70 to glycine. This suggests that Asp 70 is part of the anionic site, and that the absence of this negatively charged amino acid explains the reduced affinity of atypical cholinesterase for positively charged substrates and inhibitors. The clinical consequence of reduced affinity for succinylcholine is that none of the succinylcholine is hydrolyzed in blood and a large overdose reaches the nerve-muscle junction where it causes prolonged muscle paralysis. Silent cholinesterase has a frame shift mutation at glycine 117 which prematurely terminates protein synthesis and yields no active enzyme. The K variant, named in honor of W. Kalow, has threonine in place of alanine 539. The K variant is associated with 33% lower activity. All variants arise from a single locus as there is only one gene for human cholinesterase (EC 3.1.1.8). Comparison of amino acid sequences of esterases and proteases shows that cholinesterase belongs to a new family of serine esterases which is different from the serine proteases.
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PMID:Genetic variants of human serum cholinesterase influence metabolism of the muscle relaxant succinylcholine. 219 56

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

Some biochemical parameters of liver and liver microsomes were studied in albino rats following administration of cobra and viper venoms at dose of 2 mg/kg body weight. The total protein content in cobra venom treated (CVT) animals and DNA and RNA contents of liver and liver microsomes were almost unaltered in both the venom treated animals while total protein content was significantly reduced in viper venom treated (VVT) animals. Alkaline and acid phosphatases activities of whole liver showed significant increase in both the venom treated animals whereas the rise in cholinesterase activity in CVT animals was not significant. Lactic acid content was significantly higher in CVT animals compared to either VVT animals or controls. The glycolytic enzymes viz., aldolase, phosphohexose isomerase and lactate dehydrogenase measured in hepatic microsomal fraction were significantly reduced while alanine and aspartate aminotransferases and gamma-glutamyl transpeptidase activities of liver microsomes were significantly elevated in both the venom treated animals compared to controls.
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PMID:Biochemical studies of liver & liver microsomes in envenomated rats. 227 76

The influence of meat containing ammonia in concentrations of 0.1 and 0.3% was studied in chronic experiments on 3 generations of rats (males and females). To investigate the function of the liver, kidneys and CNS, alanine-aminotransferase, lactate dehydrogenase activity, and the content of the total protein and its fractions were assayed in the blood serum; cholinesterase activity, sulfhydryl groups, urea and residual nitrogen were assayed in the blood, as well as the parameters of rheobase, chronaxie and summation of subliminal impulses. The results of the investigation have shown that meat containing ammonia in concentrations of 0.1 and 0.3% produces a detrimental effect on the experimental animals, the highest effect being recorded with an ammonia concentration of 0.3%.
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PMID:[Study of the possible harmful action of meat containing ammonia on experimental animals]. 260 59

Purified human serum butyrylcholine esterase (approximately 90-kDa subunit), which also exhibits aryl acylamidase activity, was subjected to limited alpha-chymotrypsin digestion. Three major protein fragments of approximately 50 kDa, approximately 21 kDa and approximately 20 kDa were found to be produced, as observed by SDS-gel electrophoresis of the chymotryptic digest. The purified butyrylcholine esterase could fully bind to a Ricinus-communis-agglutinin-Sepharose column but after chymotryptic digestion about 15-20% of the enzyme activity remained unbound and was recovered in the run-through fractions. Sephadex G-75 chromatography of the chymotryptic digest showed an enzymatically active fragment eluted at an approximate molecular mass of 20 kDa, apart from the undigested butyrylcholine esterase eluted at the void volume. The butyrylcholine esterase fragment that did not bind to Ricinus communis agglutinin also was eluted at an approximate molecular mass of 20 kDa from a Sephadex G-75 column. This enzymatically active low-molecular-mass fragment from Sephadex G-75 chromatography showed a single protein band of approximately 20 kDa on SDS-gel electrophoresis. Neutral sugar analysis of the approximately 20 kDa fragment showed the presence of mannose only, whereas the undigested butyrylcholine esterase showed the presence of both mannose and galactose. Amino-terminal-sequence analysis of the approximately 20 kDa fragment showed the sequence Arg-Val-Gly-Ala-Leu, which agrees with amino acid residues 147-151 reported for human serum butyrylcholine esterase [Lockridge et al. (1987) J. Biol. Chem. 262, 549-557]. Both cholinesterase and aryl acylamidase activities were co-eluted in all chromatographic procedures. The results suggested that limited alpha-chymotrypsin digestion of human serum butyrylcholine esterase resulted in the formation of a approximately 20-kDa enzymatically active fragment with Arg147 as its N-terminal residue and which was devoid of galactose.
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PMID:Isolation of a galactose-free 20-kDa fragment exhibiting butyrylcholine esterase and aryl acylamidase activity from human serum butyrylcholine esterase by limited alpha-chymotrypsin digestion. 264 20


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