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:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although quantitative tests of some hepatic functions have been well established, the determination of serum cholinesterase activity continues to be commonly used in their stead. A critical comparison of the serum cholinesterase activity with these quantitative tests, however, is still lacking. Serum cholinesterase activity was therefore simultaneously compared with galactose elimination capacity (GEC), initial BSP-disappearance rate (BSP-ki), and serum albumin levels in 19 healthy control subjects and 46 patients with various chronic liver diseases. Serum cholinesterase activity was less discriminating between controls and patients than BSP-ki. It appears poorly suited, therefore, as a screening test for mild liver disease. Rank correlations between serum cholinesterase activity and GEC, BSP-ki, and serum albumin were statistically higher significant (r = 0.65, r = 0.74, and r = 0.80 respectively). On a statistical basis, serum cholinesterase activity may, therefore, be regarded as an index of the functional reserve of the liver. Evaluation of individual cases, however, revealed some clinically relevant discrepancies. It is concluded, therefore, that for accurate follow-up studies measurements of serum cholinesterase activity may be insufficient substitutes for the quantitative tests.
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PMID:[Blood cholinesterase and hepatic function: a comparison with BSP and galactose elimination as well as serum albumin concentration]. 70 94

Inositol glycans were prepared from reductively radiomethylated human erythrocyte acetylcholinesterase by sequential treatment with Proteinase K, methanolic KOH, and phosphatidylinositol-specific phospholipase C. Four glycans denoted alpha-delta were resolved by anion exchange high performance liquid chromatography (HPLC). Each glycan was subjected to hydrolysis in 4 M trifluoroacetic acid, and their hexose and hexose phosphate compositions were determined by anion exchange HPLC. The predominant glycan alpha showed a relative stoichiometry of 2 mannoses, 1 mannose 6-phosphate, 1 radiomethylated glucosamine, 1 radiomethylated ethanolamine, and 1 inositol. In contrast, the stoichiometry of glycan beta was 1 mannose, 2 mannose 6-phosphates, 1 radiomethylated glucosamine, 2 radiomethylated ethanolamines, and 1 inositol. Glycans alpha and beta were analyzed by electrospray ionization-mass spectrometry, and respective parent ions of m/z 1266 and 1417 were observed. The fragmentation pattern produced by collision-induced dissociation mass spectrometry of these parent ions was consistent with a common linear core glycan sequence prior to radiomethylation of ethanolamine-phosphate-mannose - mannose - mannose - glucosamine - inositol. Glycan alpha contained a single additional radiomethylated phosphoethanolamine branching from the mannose adjacent to glucosamine, whereas glycan beta contained two additional radiomethylated phosphoethanolamines, one branching from each of the mannoses nearest to glucosamine. Trifluoroacetic acid hydrolysis did not cleave within the N,N-dimethylglucosamine-inositol-phosphate moiety in these glycans, and this component was resolved by anion exchange HPLC and structurally confirmed by mass spectrometry. Dephosphorylation of this component by treatment with 50% HF produced N,N-dimethylglucosamine-inositol, and this conjugate was shown to have a characteristic elution time on cation exchange chromatography in an amino acid analyzer. Both of these fragments involving an intact radiomethylated glucosamine-inositol bond are proposed as new diagnostic indicators in the search for minor glycoinositol phospholipids in cells and tissues.
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PMID:Glycan components in the glycoinositol phospholipid anchor of human erythrocyte acetylcholinesterase. Novel fragments produced by trifluoroacetic acid. 138 56

Various liver function tests were evaluated in regard to a quantitative estimation of the impairment of liver function related to the Child-Pugh classification in 32 patients with cirrhosis. Only the ICG-test revealed significant differences between healthy subjects and cirrhotic patients in stadium Child A, B and C. When ICG-dye retention values were plotted as a function of the individual score units of the Child-Pugh classification, a linear relationship with a correlation coefficient of 0.7 was obtained. In contrast to the ICG-test, the MEGX- and galactose elimination capacity (GEC)-test as well as static parameters of liver function (cholinesterase activity, prealbumin concentration, coagulation factor V and VII) resulted in less significant differentiation of the various Child classes. The MEGX-test, GEC, concentration of prealbumin, coagulation factor V and VII were only weakly correlated to the score units of the Child-Pugh index. The results of this study indicate that of all evaluated parameters only the ICG-test is suitable for objective and graduated analysis of liver function in patients with cirrhosis.
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PMID:[Liver function tests in a clinical comparison]. 147 85

A protein fatty acylesterase activity that catalyzes the removal of fatty acid from exogenous proteolipid protein (PLP) has been demonstrated in isolated rat brain myelin. Optimum enzyme activity for the deacylation of PLP was obtained in 0.5% Triton X-100, 1 mM dithiothreitol at pH 7.0 and at 37 degrees C. Other detergents (octyl beta-D-glucoside, Nonidet P-40, and Tween 20) have little or no effect, whereas deacylation was completely abolished by 0.1% sodium dodecyl sulfate or boiling the membrane fraction for 5 min prior to incubation. Under optimal conditions, the rate of deacylation was linear up to 20 min, and the apparent Km for bovine [3H]palmitoyl-PLP was 18 microM. The myelin-associated PLP fatty acylesterase has no apparent requirements for divalent cations (Ca2+, Mg2+, Mn2+), and chelators such as EDTA, [ethylenebis(oxyethylenenitrilo)] tetraacetic acid, and 1,10-phenantroline have little or no effect on enzyme activity. Sulfhydryl and histidine residues are needed for full enzyme activity, whereas the "active serine"-directed inhibitor phenylmethylsulfonyl fluoride has no effect. The myelin-associated protein fatty acylesterase was present throughout brain development and in all myelin subfractions, in agreement with the dynamic metabolism of PLP-bound fatty acids. Enzyme activity was also present in sciatic nerve, brain cortex, and heart whereas liver was devoid of activity. Several esterases, including phospholipase A2, glyoxalase II, and acetylcholinesterase, did not remove fatty acid from PLP. Myelin basic protein, palmitoyl-CoA hydrolase, and myelin-associated nonspecific esterase were also ruled out as the PLP fatty acylesterase. Thus, all data seem to indicate that this enzyme is different from esterases of the lipid metabolism. Finally, stimulation of protein phosphorylation with Ca2+, but not with cyclic-AMP, inhibited PLP deacylation, suggesting that the myelin-associated protein fatty acylesterase activity is regulated by endogenous Ca(2+)-dependent protein kinases.
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PMID:Characterization of proteolipid protein fatty acylesterase from rat brain myelin. 156 18

Acetylcholinesterase has been isolated from bovine erythrocyte membranes by affinity chromatography using a m-trimethylammonium ligand. The purified enzyme had hydrophobic properties by the criterion of phase partitioning into Triton X-114. The activity of the hydrophobic enzyme was seen as a slow-moving band in nondenaturing polyacrylamide gels. After treatment with phosphatidylinositol-specific phospholipase C, another form of active enzyme was produced that migrated more rapidly toward the anode in these gels. This form of the enzyme partitioned into the aqueous phase in Triton X-114 phase separation experiments and was therefore hydrophilic. The hydrophobic form bound to concanavalin A in the absence of Triton X-100. As this binding was partially prevented by detergent, but not by alpha-methyl mannoside, D-glucose, or myo-inositol, it is in part hydrophobic. Erythrocyte cell membranes showed acetylcholinesterase activity present as a major form, which was hydrophobic by Triton X-114 phase separation and in nondenaturing gel electrophoresis moved at the same rate as the purified enzyme. In the membrane the enzyme was more thermostable than when purified in detergent. The hydrophobic enzyme isolated, therefore, represents a native form of the acetylcholinesterase present in the bovine erythrocyte cell membrane, but in isolation its stability becomes dependent on amphiphile concentration. Its hydrophobic properties and lectin binding are attributable to the association with the protein of a lipid with the characteristics of a phosphatidylinositol.
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PMID:Influence of associated lipid on the properties of purified bovine erythrocyte acetylcholinesterase. 203 16

Purified human serum butyrylcholinesterase (approximately 90-kDa subunit) is known to exhibit aryl acylamidase and peptidase activity. Limited alpha-chymotrypsin digestion of the purified butyrylcholinesterase gave three major protein fragments of approximately 50 kDa, approximately 21 kDa and approximately 20 kDa. In our earlier studies [Rao and Balasubramanian (1989) Eur. J. Biochem. 179, 639-644] we characterized the approximately 20-kDa fragment and showed that it exhibited both butyrylcholinesterase and aryl acylamidase activities. In the present studies the approximately 50-kDa fragment is characterized. This fragment, after isolation by Sephadex G-75 chromatography from a chymotryptic digest of purified butyrylcholinesterase, exhibited only peptidase activity and was devoid of cholinesterase and aryl acylamidase activities. It could bind to a column of Ricinus communis agglutinin bound to Sepharose, indicating its glycosylated nature and the presence of galactose. The peptidase activity in the approximately 50-kDa fragment could be immuno-precipitated by a polyclonal antibody raised against purified butyrylcholinesterase. SDS-gel electrophoresis of this fragment isolated by R. communis agglutinin-Sepharose and Sephadex G-75 chromatography showed a protein band of approximately 50 kDa by silver staining. Amino-terminal sequence analysis of the approximately 50-kDa fragment gave the sequence of Gly-Pro-Thr-Val-Asp which corresponded to amino acid residues 291-295 in the butyrylcholinesterase sequence [Lockridge et al. (1987) J. Biol. Chem. 262, 549-557]. The combined results suggested that alpha-chymotrypsin digestion of human serum butyrylcholinesterase resulted in the formation of a approximately 20-kDa fragment exhibiting both cholinesterase and aryl acylamidase activities and a approximately 50-kDa fragment exhibiting only peptidase activity.
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PMID:Localization of the peptidase activity of human serum butyrylcholinesterase in a approximately 50-kDa fragment obtained by limited alpha-chymotrypsin digestion. 233 89

Primary cultures of hippocampal neurons are important for the study of trace elements in epileptogenesis. We developed a model system for culturing hippocampal neurons on poly-L-lysine in Iscove's modification of Dulbecco's MEM (IMDM) supplemented with K+, D-glucose, glutamine, insulin, p-amino benzoic acid, transferrin, BSA, beta-estradiol, gentamycin, and fungizone. Neurons were identified by histochemical staining for cholinesterase. Zinc at concentrations of 10(-9) to 10(-6) M induced metallothionein in hippocampal neuronal cultures. Maximum metallothionein induction occurred after 48 hrs incubation with zinc.
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PMID:Metallothionein induction in rat hippocampal neurons in primary culture. 251 54

A method for rapid assessment of hepatic function in liver donors based on the formation of the lignocaine metabolite monoethylglycinexylidide (MEGX), was used in a prospective study of 69 donor-recipient pairs. The probability of graft survival over 120 days was significantly higher for livers from donors with MEGX test values above 90 micrograms/l than for those from donors with MEGX values of 90 micrograms/l or below. Other liver function tests (bilirubin, prothrombin time, activity of aminotransferases, glutamate dehydrogenase, and cholinesterase, indocyanine green clearance, and galactose elimination capacity) were inefficient at predicting early outcome of transplantation. For a 20-day graft survival, the MEGX test showed prognostic sensitivity of 73% and specificity of 78%. These findings suggest that the MEGX formation test could be valuable for selection of donor organs.
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PMID:Lignocaine metabolite formation as a measure of pre-transplant liver function. 256 60

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

The glycoinositol phospholipid membrane anchor of human erythrocyte acetylcholinesterase (EC 3.1.1.7) is composed of a glycan linked through a glucosamine residue to an inositol phospholipid that is resistant to the action of phosphatidylinositol-specific phospholipase C. Deamination cleavage of the glucosamine with nitrous acid released the inositol phospholipid which was purified by high performance liquid chromatography. Analysis by fast atom bombardment mass spectrometry with negative ion monitoring and by the complementary technique of collision-induced dissociation revealed molecular and daughter ions that indicated a plasmanylinositol with a palmitoyl group on an inositol hydroxyl. The intact membrane anchor was released from reductively methylated human erythrocyte acetylcholinesterase by proteolysis with papain or Pronase, deacylated by base hydrolysis, and purified by high performance liquid chromatography. Positive and negative ion fast atom bombardment mass spectrometry of the major products isolated by high performance liquid chromatography indicated the following structure for the complete glycoinositol phospholipid anchor. (formula; see text) Methylation of free amino groups by reduction with deuterium instead of hydrogen permitted determination of the number of free amino groups in individual fragment ions as further confirmation of structural assignments. The structure of the glycan portion of the human erythrocyte acetylcholinesterase membrane anchor appears to be similar to that described for Trypanosome brucei variant surface glycoprotein MITat 1.4 (variant 117) (Ferguson, M.A.J., Homans, S.W., Dwek, R.A., and Rademacher, T.W. (1988) Science 239, 753-759) except for the absence of a galactose antenna and the presence of a phosphorylethanolamine on the hexose adjacent to glucosamine.
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PMID:Structural characterization of the glycoinositol phospholipid membrane anchor of human erythrocyte acetylcholinesterase by fast atom bombardment mass spectrometry. 284 7


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