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)

The electrokinetic behavior of red cell membrane vesicles of normal (ROV) and inverted (IOV) sidedness has been characterized using the laser Doppler technique of electrophoretic light scattering (ELS). At neutral pH ROV have a (approx. 25%) higher electrophoretic mobility than IOV and the two peaks can be resolved in the ELS spectrum to provide a quantitative estimate of the IOV/ROV ratio which is consistent with the ratio determined by assay of the activity of acetylcholinesterase. The ROV peak coincides with the mobility of fresh red blood cells and of resealed ghosts. Neuraminidase treatment reduces the ROV mobility by a factor of 2.6, while the IOV peak is reduced only slightly (less than 5%). Treatment with trypsin results in a single narrow ELS peak at about 60% of the mobility of ROV. Treatment of IOV with phospholipase C leaves the electrophoretic mobility unaltered, whereas treatment with phospholipase D increases their mode mobility by 22%. The mobility titration curve of IOV from pH 2 to pH 10 reveals three distinct inflection points which may be assigned to chemical groups on the cytoplasmic surface of the red cell membrane.
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PMID:Electrokinetic behavior of inside-out vesicles from human red cell membranes. 711 10

The presence of GPI anchors and phospholipases capable of solubilizing them in Trypanosoma cruzi has been investigated in epimastigotes, metacyclic trypomastigotes from axenic cultures and tissue culture trypomastigotes. The GPI anchored proteins in epimastigote forms are scarce when compared to their abundance in the parasite forms which can infect mammals, and GPI-solubilizing phospholipases C have been found in all life cycles stages. In epimastigote and metacyclic forms, the activity is found in the soluble fraction upon cell lysis, whereas in tissue cultured trypomastigotes it is membrane bound and, being mostly sensitive to p-chloromercuriphenylsulfonate, resembles closely the GPI specific phospholipase of Trypanosoma brucei. Sequential immunoprecipitations with monoclonal antibodies and anti-CRD indicated the presence of several sub-populations among the surface proteins of metacyclic trypomastigotes, five of these belonging to the GPI-anchored 90 kD family. Among this family, the epitopes recognized by MAb-1G7 are present in three members, one of them also expressing the 3F6 epitope. There are 2 members recognized only by MAb-3F6 but not by MAb-1G7, one of them being probably galactosylated on the GPI since it can be immunoprecipitated by anti-CRD. Very strangely, the epitope recognized by the MAb-WIC29.26 was always present on the gp72, as originally described, but under certain circumstances appeared cryptic on one of the 90 kD species. During epimastigote transformation into metacyclic trypomastigotes in vitro, the ability of the GPI of the 1G7-antigen to be solubilized by phospholipase C and D varies depending on the age of the culture and presence or absence of fetal calf serum. Different patterns of solubilization were also obtained for 1G7-Ag, depending on whether the test is performed with parasite lysates or with antigen affinity purified from them. Our data indicate that the phospholipase C resistance observed does not arise from acylation on the inositol, as previously described for acetylcholinesterase from human erythrocytes, being rather due to factors which either modify the GPI or affect the action of the phospholipases. Previously unreported resistance to glycosylphosphatidylinositol-specific phospholipase D has been observed both to glycosylphosphatidylinositol-specific phospholipase D has been observed both to 1G7-Ag and 10D8-Ag, the GPI-anchored mucynlike protein which is acceptor of sialic acid in metacyclic forms. Our findings are discussed in the light of the presently known structures of GPI in this parasite, and imaginative speculation on biological roles for the GPI phospholipase system in T. cruzi is also provided.
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PMID:Proteins anchored via glycosylphosphatidylinositol and solubilizing phospholipases in Trypanosoma cruzi. 767 May 41

It has been suggested previously that small amounts of the mature 115-kDa form of phosphatidylinositol (PtdIns)-glycan-specific phospholipase D from bovine serum may exist as a 47-kDa form which can also be generated in vitro by treatment with proteases. In this study, we investigated the possible proteolytic processing by trypsin of partially purified PtdIns-glycan- specific phospholipase D from bovine serum and found that tryptic digestion caused an apparent activation of the enzyme when assayed in the presence of 0.1% (mass/vol.) Triton X-100. Trypsin cleaved the 115-kDa form of PtdIns-glycan-specific phospholipase D into three major polypeptides with molecular masses of 33, 39, and 47 kDa. Under non-denaturing conditions, the polypeptides remained tightly but noncovalently associated with each other. However, in the presence of 6 M urea, the polypeptides could be separated by anion-exchange chromatography. After renaturation, PtdIns-glycan-specific phospholipase D activity was found to be associated with a 39-kDa fragment. Based on its size and its amino acid sequence, the active-site-containing fragment consisted of approximately 275 residues of the N-terminal region of PtdIns-glycan-specific phospholipase D. The active 39-kDa fragment hydrolyzed the PtdIns-glycan-anchors of solubilized acetylcholinesterase from bovine erythrocytes and variant surface glycoprotein from blood stream trypanosomes. However, this fragment was inactive on membrane-associated acetylcholinesterase and PtdIns.
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PMID:Generation by limited proteolysis of a catalytically active 39-kDa protein from the 115-kDa form of phosphatidylinositol-glycan-specific phospholipase D from bovine serum. 792 7

Glycosyl-phosphatidylinositol-specific phospholipase D (GPI-PLD) is an amphiphilic protein which, in serum, is associated with high-density lipoproteins (HDL). It is shown that the major component of the HDL fraction, apolipoprotein A-I (apo A-I), is responsible for this association. In the absence of apo A-I, purified GPI-PLD occurred as virtually inactive aggregates which became disaggregated by apo A-I. The enzyme/apo A-I complex efficiently hydrolyzed the solubilized GPI-anchored substrate, acetylcholinesterase. Triton X-100 was also able to dissociate aggregated GPI-PLD, however, it strongly inhibited enzyme activity at detergent concentrations above the critical micellar concentration.
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PMID:Glycosyl-phosphatidylinositol-specific phospholipase D. Interaction with and stimulation by apolipoprotein A-I. 833 9

Several mammalian enzymes are anchored to the outer surface of the plasma membrane by a covalently attached glycosylphosphatidylinositol (GPI) structure. These include acetylcholinesterase, alkaline phosphatase (AP) and 5'-nucleotidase among other enzymes. Recently, it has been reported that these membrane enzymes can be released into the serum by the GPI-dependent phospholipase D under various medical disturbances such as cancer and/or by chemical and physical manipulation of the biological systems. Treatment of MCF-7 cells with two consecutive effective concentrations of 3-hydrogenkwadaphnin (3-HK, 3 nM) for 48 h enhanced membrane AP activity by almost 330% along with a 40% reduction in the AP activity of the cell culture medium. In addition, our data indicate that 3-HK is capable of inducing mainly the tissue-nonspecific alkaline phosphatase (TNAP) isoenzyme, along with enhancing its thermostability. These findings, besides establishing a correlation between the antiproliferative activity of 3-HK and the extent of plasma membrane AP activity, might assist in the development of new diagnostic tools for following cancer medical treatments.
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PMID:Plasma membrane homing of tissue nonspecific alkaline phosphatase under the influence of 3-hydrogenkwadaphnin, an antiproliferative agent from Dendrostellera lessertii. 1752 90


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