Gentry MK

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Full name : Gentry Mary Kay

First name : Mary Kay

Mail : Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC 20307-5100

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Country : USA

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References (27)

Title : Stable Complexes Involving Acetylcholinesterase and Amyloid-beta Peptide Change the Biochemical Properties of the Enzyme and Increase the Neurotoxicity of Alzheimer's Fibrils - Alvarez_1998_J.Neurosci_18_3213
Author(s) : Alvarez A , Alarcon R , Opazo C , Campos EO , Munoz FJ , Calderon FH , Dajas F , Gentry MK , Doctor BP , de Mello FG , Inestrosa NC
Ref : Journal of Neuroscience , 18 :3213 , 1998
Abstract : Brain acetylcholinesterase (AChE) forms stable complexes with amyloid-beta peptide (Abeta) during its assembly into filaments, in agreement with its colocalization with the Abeta deposits of Alzheimer's brain. The association of the enzyme with nascent Abeta aggregates occurs as early as after 30 min of incubation. Analysis of the catalytic activity of the AChE incorporated into these complexes shows an anomalous behavior reminiscent of the AChE associated with senile plaques, which includes a resistance to low pH, high substrate concentrations, and lower sensitivity to AChE inhibitors. Furthermore, the toxicity of the AChE-amyloid complexes is higher than that of the Abeta aggregates alone. Thus, in addition to its possible role as a heterogeneous nucleator during amyloid formation, AChE, by forming such stable complexes, may increase the neurotoxicity of Abeta fibrils and thus may determine the selective neuronal loss observed in Alzheimer's brain.
ESTHER : Alvarez_1998_J.Neurosci_18_3213
PubMedSearch : Alvarez_1998_J.Neurosci_18_3213
PubMedID: 9547230

Title : A Comparison of Blood Cholinesterase Activities, Pyridostigmine Inhibition of Red Cell Acetylcholinesterase, and Butyrylcholinesterase Phenotypes in Gulf War Veterans and Normal Controls -
Author(s) : Gentry MK , Powell S , Bitsko N , Bartels CF , Bartko J , Chung R , Lockridge O , Ribas J , Roy M , Malone J , Doctor BP
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :300 , 1998
PubMedID:

Title : A monoclonal antibody against acetylcholinesterase inhibits the formation of amyloid fibrils induced by the enzyme - Reyes_1997_Biochem.Biophys.Res.Commun_232_652
Author(s) : Reyes AE , Perez DR , Alvarez A , Garrido J , Gentry MK , Doctor BP , Inestrosa NC
Ref : Biochemical & Biophysical Research Communications , 232 :652 , 1997
Abstract : A monoclonal antibody (mAb) 25B1 directed against fetal bovine-serum acetylcholinesterase (FBS AChE) was used to examine the ability of the cholinergic enzyme to promote the assembly of amyloid-beta peptides (A beta) into Alzheimer fibrils. This mAb binds to the peripheral anionic site of the enzyme and allosterically inhibits catalytic activity of FBS AChE. Several techniques, including thioflavine-T fluorescence, turbidity, and negative-staining at the electron microscopy level, were used to assess amyloid formation. Inhibition of amyloid formation was dependent on the molar ratio AChE:mAb 25B1, and at least 50% of the inhibition of the AChE promoting effect occurs at a molar ratio similar to that required for inhibition of the esterase activity. Our results suggest that mAb 25B1 inhibits the promotion of the amyloid fibril formation triggered by AChE by affecting the lag period of the A beta aggregation process.
ESTHER : Reyes_1997_Biochem.Biophys.Res.Commun_232_652
PubMedSearch : Reyes_1997_Biochem.Biophys.Res.Commun_232_652
PubMedID: 9126330

Title : Amino Acid Alignment of Cholinesterases, Esterases, Lipases, and Related Proteins -
Author(s) : Gentry MK , Doctor BP
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :493 , 1995
PubMedID:

Title : Alterations in the Topography of Acetylcholinesterase Active Site Gorge after Binding of Peripheral Anionic Site Ligands -
Author(s) : Stalc A , Grubic Z , Sentjurc M , Pecar S , Gentry MK , Doctor BP
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :125 , 1995
PubMedID:

Title : Modulation of Catalysis and Inhibition of Fetal Bovine Serum Acetylcholinesterase by Monoclonal Antibodies -
Author(s) : Doctor BP , Gentry MK , Saxena A , Ashani Y
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :141 , 1995
PubMedID:

Title : Different effects of two peripheral anionic site-binding ligands on acetylcholinesterase active-site gorge topography revealed by electron paramagnetic resonance - Grubic_1995_Biochim.Biophys.Acta_1249_155
Author(s) : Grubic Z , Stalc A , Sentjurc M , Pecar S , Gentry MK , Doctor BP
Ref : Biochimica & Biophysica Acta , 1249 :155 , 1995
Abstract : Both propidium and monoclonal antibody (mAb) 25B1 bind to the peripheral anionic site region of fetal bovine serum acetylcholinesterase (FBS AChE). Using electron paramagnetic resonance (EPR) with spin-labelled organophosphate specifically bound to the AChE active-site serine, we studied the effects of both ligands on the topography of the AChE active-site gorge. After incubation of FBS AChE with Fab fragments of mAb 25B1, freedom of motion of our spin label became more restricted, suggesting closing of the gorge. Stabilization against heat denaturation was also observed. No alterations in the freedom of motion or protection against heat denaturation could be detected after propidium binding. Our results demonstrate that two ligands binding to the peripheral anionic site region of AChE have different effects, suggesting a complex structure for this region of the molecule that allows various types of interactions with different ligands. We also demonstrate that EPR is a suitable tool for studying microtopographical alterations at the active sites of cholinesterases.
ESTHER : Grubic_1995_Biochim.Biophys.Acta_1249_155
PubMedSearch : Grubic_1995_Biochim.Biophys.Acta_1249_155
PubMedID: 7599168

Title : Characterization of monoclonal antibodies that inhibit the catalytic activity of acetylcholinesterases - Gentry_1995_J.Neurochem_64_842
Author(s) : Gentry MK , Moorad DR , Hur RS , Saxena A , Ashani Y , Doctor BP
Ref : Journal of Neurochemistry , 64 :842 , 1995
Abstract : Monoclonal antibodies were generated against fetal bovine serum acetylcholinesterase and fetal bovine serum acetylcholinesterase inhibited by diisopropyl fluorophosphate or 7-(methylethoxyphosphinyloxy)-1-methylquinolinium iodide. Six monoclonal antibodies inhibited 70 to > 98% of the catalytic activity of fetal bovine serum acetylcholinesterase. Inhibition of serum acetylcholinesterase from several mammalia by four monoclonal antibodies showed broad cross-reactivity. In all cases, monoclonal antibodies bound to the native form of acetylcholinesterases. None reacted with serum butyrylcholinesterases from various species. Although all monoclonal antibodies inhibited catalytic activity of acetylcholinesterases, the site of interaction with acetylcholinesterase appeared to differ for several antibodies. Two types of acetylcholinesterase:monoclonal antibody complexes were formed: one between tetrameric forms and another between catalytic subunits within the tetramer. Monoclonal antibodies that inhibited acetylcholinesterase activity at > 98% also considerably slowed binding of diisopropyl fluorophosphate and other organophosphorus compounds to the acetylcholinesterase:monoclonal antibody complex. Binding of these monoclonal antibodies to acetylcholinesterase influenced function of the enzyme's peripheral anionic site. None of the antibodies bound to the esteratic site of acetylcholinesterase. Monoclonal antibodies caused changes in catalytic activity of acetylcholinesterase by interaction at a site remote from the catalytic site, presumably at the entrance to the active site gorge.
ESTHER : Gentry_1995_J.Neurochem_64_842
PubMedSearch : Gentry_1995_J.Neurochem_64_842
PubMedID: 7830078

Title : Relationship between sequence conservation and three-dimensional structure in a large family of esterases, lipases, and related proteins - Cygler_1993_Protein.Sci_2_366
Author(s) : Cygler M , Schrag JD , Sussman JL , Harel M , Silman I , Gentry MK , Doctor BP
Ref : Protein Science , 2 :366 , 1993
Abstract : Based on the recently determined X-ray structures of Torpedo californica acetylcholinesterase and Geotrichum candidum lipase and on their three-dimensional superposition, an improved alignment of a collection of 32 related amino acid sequences of other esterases, lipases, and related proteins was obtained. On the basis of this alignment, 24 residues are found to be invariant in 29 sequences of hydrolytic enzymes, and an additional 49 are well conserved. The conservation in the three remaining sequences is somewhat lower. The conserved residues include the active site, disulfide bridges, salt bridges, and residues in the core of the proteins. Most invariant residues are located at the edges of secondary structural elements. A clear structural basis for the preservation of many of these residues can be determined from comparison of the two X-ray structures.
ESTHER : Cygler_1993_Protein.Sci_2_366
PubMedSearch : Cygler_1993_Protein.Sci_2_366
PubMedID: 8453375

Title : Epitope mapping of form-specific and nonspecific antibodies to acetylcholinesterase - Wasserman_1993_J.Neurochem_61_2124
Author(s) : Wasserman L , Doctor BP , Gentry MK , Taylor P
Ref : Journal of Neurochemistry , 61 :2124 , 1993
Abstract : We have mapped the epitopes to which two monoclonal antibodies against acetylcholinesterase (AChE) from Torpedo californica are directed. One antibody, 2C9, has equivalent affinity for both the 5.6S (amphiphilic) and 11S (hydrophilic) enzyme forms; the other, 4E7, recognizes only the amphiphilic form and has been shown previously to require an N-linked oligosaccharide residue on the protein. Isolation of cyanogen bromide peptides from the amphiphilic form and assay by a competition ELISA for 2C9 and by a direct binding ELISA for 4E7 identified the same peptide, residues 44-82, as containing epitopes against both antibodies. The epitope for 4E7 includes the oligosaccharide conjugated to Asp59, an N-linked glycosylation site not present in mouse AChE. A 20-amino-acid synthetic peptide, RFRRPEPKKPWSGVWNASTY, representing residues 44-63, was synthesized and found to inhibit completely 2C9 binding to 5.6S enzyme at molar concentrations comparable to those of the cyanogen bromide peptide. It was unreactive with 4E7. Fractionation of the synthetic peptide further localized the 2C9 epitope. Peptides RFRRPEPKKPW and KPWSGVWNASTY both reacted but less so than the entire synthetic peptide at equivalent molar concentrations, whereas the peptide RPEPKKPWSGVWNASTY was as effective as the larger synthetic peptide. The crystal structure of AChE shows the peptide to be on the surface of the molecule as part of a convex hairpin loop starting before the first alpha-helix.
ESTHER : Wasserman_1993_J.Neurochem_61_2124
PubMedSearch : Wasserman_1993_J.Neurochem_61_2124
PubMedID: 7504082

Title : Cholinesterases as scavengers for organophosphorus compounds: protection of primate performance against soman toxicity - Doctor_1993_Chem.Biol.Interact_87_285
Author(s) : Doctor BP , Blick DW , Caranto G , Castro CA , Gentry MK , Larrison RW , Maxwell DM , Murphy MR , Schutz MB , Waibel KH , Wolfe AD
Ref : Chemico-Biological Interactions , 87 :285 , 1993
Abstract : The present treatment for poisoning by organophosphates consists of multiple drugs such as carbamates, antimuscarinics, and reactivators in pre- and post-exposure modalities. Recently an anticonvulsant, diazapam, has been included as a post-exposure drug to reduce convulsions and increase survival. Most regimens are effective in preventing lethality from organophosphate exposure but do not prevent toxic effects and incapacitation observed in animals and likely to occur in humans. Use of enzymes such as cholinesterases as pretreatment drugs for sequestration of highly toxic organophosphate anticholinesterases and alleviation of side effects and performance decrements was successful in animals, including non-human primates. Pretreatment of rhesus monkeys with fetal bovine serum acetylcholinesterase protected them against lethal effects of soman (up to 5 LD50) and prevented signs of OP toxicity. Monkeys pretreated with fetal bovine serum acetylcholinesterase were devoid of behavioral incapacitation after soman exposure, as measured by serial probe recognition or primate equilibrium platform performance tasks. Use of acetylcholinesterase as a single pretreatment drug provided greater protection against both lethal and behavioral effects of potent organophosphates than current multicomponent drug treatments that prevent neither signs of toxicity nor behavioral deficits. Although use of cholinesterases as single pretreatment drugs provided complete protection, its use for humans may be limited, since large quantities will be required, due to the approximately 1:1 stoichiometry between organophosphate and enzyme. Bisquaternary oximes, particularly HI-6, have been shown to reactivate organophosphate-inhibited acetylcholinesterase at a rapid rate. We explored the possibility that enzyme could be continually reactivated in animals pretreated with fetal bovine serum acetylcholinesterase, followed by an appropriate dose of reactivator, and challenged with repeated doses of sarin. In in vitro experiments, stoichiometry greater than 1:400 for enzyme:sarin was achieved; in vivo stoichiometry in mice was 1:65. Pretreatment of mice with fetal bovine serum acetylcholinesterase and HI-6 amplified the effectiveness of exogenous enzyme as a scavenger for organophosphate.
ESTHER : Doctor_1993_Chem.Biol.Interact_87_285
PubMedSearch : Doctor_1993_Chem.Biol.Interact_87_285
PubMedID: 8343986

Title : Immunochemical characterization of anti-acetylcholinesterase inhibitory monoclonal antibodies - Gentry_1993_Chem.Biol.Interact_87_227
Author(s) : Gentry MK , Saxena A , Ashani Y , Doctor BP
Ref : Chemico-Biological Interactions , 87 :227 , 1993
Abstract : Monoclonal antibodies (mAbs) were prepared against native or DFP-inhibited Torpedo californica acetylcholinesterase and native or DFP-, MEPQ-, and soman-inhibited fetal bovine serum acetylcholinesterase. The cross reactivity of these antibodies with acetylcholinesterases from various species and their ability to inhibit catalytic activity were determined. Eight antibodies were found to inhibit catalytic activity of either Torpedo or fetal bovine serum enzyme. In all cases the antibodies bound to the native form of the enzymes and in some cases even to the denatured form. None of the antibodies recognized human or horse serum butyrylcholinesterase. Sucrose density gradient centrifugation of enzyme-antibody complexes provided two types of profiles, one with multiple peaks, indicating numerous complexes between tetrameric forms of the enzyme, and the other with single peaks, demonstrating complex formation within the tetrameric form. Different antibodies appeared to interact with slightly different regions, but in all cases the binding encompassed the peripheral anionic site. Decrease in catalytic activity of the enzyme was most likely caused by conformational changes in the enzyme molecule resulting from interaction with these mAbs.
ESTHER : Gentry_1993_Chem.Biol.Interact_87_227
PubMedSearch : Gentry_1993_Chem.Biol.Interact_87_227
PubMedID: 7688272

Title : Protection of rhesus monkeys against soman and prevention of performance decrement by pretreatment with acetylcholinesterase - Maxwell_1992_Toxicol.Appl.Pharmacol_115_44
Author(s) : Maxwell DM , Castro CA , De La Hoz DM , Gentry MK , Gold MB , Solana RP , Wolfe AD , Doctor BP
Ref : Toxicology & Applied Pharmacology , 115 :44 , 1992
Abstract : The ability of acetylcholinesterase from fetal bovine serum (FBS AChE) to protect against soman, a highly toxic organophosphorus (OP) compound, was tested in rhesus monkeys. Intravenous administration of FBS AChE produced a minimal behavioral effect on the serial probe recognition task, a sensitive test of cognitive function and short-term memory. Pharmacokinetic studies of injected FBS AChE indicated a plasma half-life of 40 hr for FBS AChE in monkeys. Both in vitro and in vivo titration of FBS AChE with soman produced a 1:1 stoichiometry between organophosphate-inhibited FBS AChE and the cumulative dose of the toxic stereoisomers of soman. Administration of FBS AChE protected monkeys against the lethal effects of up to 2.7 LD50 of soman and prevented any signs of organophosphate intoxication, e.g., excessive secretions, respiratory depression, muscle fasciculations, or convulsions. In addition, monkeys pretreated with FBS AChE were devoid of any behavioral incapacitation after soman challenge, as measured by the serial probe recognition task. Compared to the current multicomponent drug treatment against soman, which does not prevent the signs or the behavioral deficits resulting from OP intoxication, use of FBS AChE as a single pretreatment drug provides significantly effective protection against both the lethal and the behavioral effects of soman.
ESTHER : Maxwell_1992_Toxicol.Appl.Pharmacol_115_44
PubMedSearch : Maxwell_1992_Toxicol.Appl.Pharmacol_115_44
PubMedID: 1631892

Title : A microtiter assay for determining protein, acetylcholinesterase activity, and G418 (Neomycin) resistance in cultured cells - Elson_1992_Anal.Biochem_200_268
Author(s) : Elson HF , Gentry MK , Doctor BP
Ref : Analytical Biochemistry , 200 :268 , 1992
Abstract : The Coomassie brilliant blue assay for the determination of protein has been extended to rapidly and conveniently measure the protein concentration of cells growing in culture in a 96-well microtiter format. Modifications of the standard assay include sodium hydroxide to solubilize the cells and ovalbumin, instead of bovine serum albumin, as a protein standard. The procedure allows a large number of small samples to be assayed simultaneously. Two examples of its use, enzyme-specific activity and drug resistance, are shown. An assay for acetylcholinesterase activity in the same culture plate is demonstrated. G418, an inhibitor of cell protein synthesis, is frequently used to select for cells transfected with the neomycin resistance gene. The required concentration of G418 can be easily determined with this protein assay.
ESTHER : Elson_1992_Anal.Biochem_200_268
PubMedSearch : Elson_1992_Anal.Biochem_200_268
PubMedID: 1378703

Title : Use of cholinesterases as pretreatment drugs for the protection of rhesus monkeys against soman toxicity - Wolfe_1992_Toxicol.Appl.Pharmacol_117_189
Author(s) : Wolfe AD , Blick DW , Murphy MR , Miller SA , Gentry MK , Hartgraves SL , Doctor BP
Ref : Toxicology & Applied Pharmacology , 117 :189 , 1992
Abstract : Purified fetal bovine serum acetylcholinesterase (FBS AChE) and horse serum butyrylcholinesterase (BChE) were successfully used as single pretreatment drugs for the prevention of pinacolyl methylphosphonofluoridate (soman) toxicity in nonhuman primates. Eight rhesus monkeys, trained to perform Primate Equilibrium Platform (PEP) tasks, were pretreated with FBS AChE or BChE and challenged with a cumulative level of five median lethal doses (LD50) of soman. All ChE-pretreated monkeys survived the soman challenge and showed no symptoms of soman toxicity. A quantitative linear relation was observed between the soman dose and the neutralization of blood ChE. None of the four AChE-pretreated animals showed PEP task decrements, even though administration of soman irreversibly inhibited nearly all of the exogenously administered AChE. In two of four BChE-pretreated animals, a small transient PEP performance decrement occurred when the cumulative soman dose exceeded 4 LD50. Performance decrements observed under BChE protection were modest by the usual standards of organophosphorus compound toxicity. No residual or delayed performance decrements or other untoward effects were observed during 6 weeks of post-exposure testing with either ChE.
ESTHER : Wolfe_1992_Toxicol.Appl.Pharmacol_117_189
PubMedSearch : Wolfe_1992_Toxicol.Appl.Pharmacol_117_189
PubMedID: 1471150

Title : Membrane-bound acetylcholinesterase: an early differentiation marker for skeletal myoblasts - Elson_1992_Biochim.Biophys.Acta_1156_78
Author(s) : Elson HF , Gentry MK , Doctor BP
Ref : Biochimica & Biophysica Acta , 1156 :78 , 1992
Abstract : Cell-bound acetylcholinesterase (AChE) was found to be an early differentiation marker on embryonic chick skeletal myoblasts in mixed primary cell cultures. AChE biosynthesis was detected and characterized by (a) a sensitive microtiter assay, (b) use of selective inhibitors, and (c) with mono- and polyclonal antibodies. Both secreted and cell-bound AChE appeared on the first day in culture, at a time when no muscle cell fusion was observed. Characterization of this enzyme revealed that true AChE was bound and secreted by myoblasts. BW284c51, which permeates cell membranes poorly, inhibited all the cell-associated AChE activity on myoblasts, suggesting that the activity measured was on the outer cell surface. On the other hand, fibroblasts appeared to have no or very little bound enzyme and the low level of secreted enzyme activity had the characteristics of pseudo-, or butyrylcholinesterase. Polyclonal anti-Torpedo californica electroplax AChE antibody and several monoclonal antibodies were found to bind specifically to chick myoblasts. Since the cells had not been made permeable before antibody binding, a membrane-bound form of the enzyme was most likely being detected. The cell-bound true AChE was present in identifiable quantities from the first day of culture. Membrane-bound AChE can thus serve as an early differentiation marker for embryonic chick myoblasts in mixed primary cultures.
ESTHER : Elson_1992_Biochim.Biophys.Acta_1156_78
PubMedSearch : Elson_1992_Biochim.Biophys.Acta_1156_78
PubMedID: 1472543

Title : Fetal Bovine Serum Acetylcholinesterase: Structure-Function Correlation -
Author(s) : Doctor BP , Gentry MK , Wu SJ , Ashani Y , De La Hoz DM
Ref : In: Cholinesterases: Structure, Function, Mechanism, Genetics, and Cell Biology , (Massoulie J, Barnard EA, Chatonnet A, Bacou F, Doctor BP, Quinn DM) American Chemical Society, Washington, DC :37 , 1991
PubMedID:

Title : Changes in the Catalytic Activity of Acetylcholinesterase upon Complexation with Monoclonal Antibodies -
Author(s) : Ashani Y , Bromberg A , Levy D , Gentry MK , Brady DR , Doctor BP
Ref : In: Cholinesterases: Structure, Function, Mechanism, Genetics, and Cell Biology , (Massoulie J, Barnard EA, Chatonnet A, Bacou F, Doctor BP, Quinn DM) American Chemical Society, Washington, DC :235 , 1991
PubMedID:

Title : APPENDIX Alignment of Amino Acid Sequences of Acetylcholinesterases and Butyrylcholinesterases -
Author(s) : Gentry MK , Doctor BP
Ref : In: Cholinesterases: Structure, Function, Mechanism, Genetics, and Cell Biology , (Massoulie J, Barnard EA, Chatonnet A, Bacou F, Doctor BP, Quinn DM) American Chemical Society, Washington, DC :394 , 1991
PubMedID:

Title : Poster: Immunocytochemical localization of phosphatidylinositol-anchored acetylcholinesterase in excitable membranes of Torpedo ocellata -
Author(s) : Eichler J , Silman I , Gentry MK , Anglister L
Ref : In: Cholinesterases: Structure, Function, Mechanism, Genetics, and Cell Biology , (Massoulie J, Barnard EA, Chatonnet A, Bacou F, Doctor BP, Quinn DM) American Chemical Society, Washington, DC :49 , 1991
PubMedID:

Title : Differences in conformational stability between native and phosphorylated acetylcholinesterase as evidenced by a monoclonal antibody - Ashani_1990_Biochemistry_29_2456
Author(s) : Ashani Y , Gentry MK , Doctor BP
Ref : Biochemistry , 29 :2456 , 1990
Abstract : Monoclonal antibody 25B1 generated against diisopropyl phosphorofluoridate inhibited fetal bovine serum acetylcholinesterase has been extensively characterized with respect to its anticholinesterase properties. This antibody demonstrated considerably different properties from previously reported inhibitory antibodies raised against acetylcholinesterase in terms of the degree of inhibition (greater than 98%), the high degree of specificity, and the stability of the antigen-antibody complex. Monoclonal antibody 25B1 appears to be directed against a conformational epitope located in close proximity to the catalytic center of the enzyme and was found to be most suitable for studying the stabilization of the active site of acetylcholinesterase against denaturation by heat or guanidine following phosphorylation by organophosphorus anticholinesterase compounds. This approach allowed the determination of stability rank order of various phosphorylated acetylcholinesterases. Among all the organophosphates tested, the combination of a methyl group and a negatively charged oxygen attached to the P atom, CH3P(O)(O-)-AChE, conferred the greatest protection to the active site of aged or nonaged organophosphoryl conjugates of acetylcholinesterase.
ESTHER : Ashani_1990_Biochemistry_29_2456
PubMedSearch : Ashani_1990_Biochemistry_29_2456
PubMedID: 1692236

Title : Studies on the topography of the catalytic site of acetylcholinesterase using polyclonal and monoclonal antibodies - Ogert_1990_J.Neurochem_55_756
Author(s) : Ogert RA , Gentry MK , Richardson EC , Deal CD , Abramson SN , Alving CR , Taylor P , Doctor BP
Ref : Journal of Neurochemistry , 55 :756 , 1990
Abstract : Polyclonal and monoclonal antibodies were generated against a synthetic peptide (25 amino acid residues) corresponding to the amino acid sequence surrounding the active site serine of Torpedo californica acetylcholinesterase (AChE). Prior to immunization, the peptide was either coupled to bovine serum albumin or encapsulated into liposomes containing lipid A as an adjuvant. To determine whether this region of AChE is located on the surface of the enzyme and thus accessible for binding to antibodies, or located in a pocket and thus not accessible to antibodies, the immunoreactivity of the antibodies was determined using enzyme-linked immunosorbent assay (ELISA), immunoprecipitation, Western blots, and competition ELISA. The polyclonal antibody and several of the monoclonal antibodies failed to react with either Torpedo or fetal bovine serum AChE in their native conformations, but showed significant cross-reactivity with the denatured enzymes. Human serum butyrylcholinesterase, which has a high degree of amino acid sequence homology with these AChEs, failed to react with the same antibodies in either native form or denatured form. Chymotrypsin also failed to react with the monoclonal antibodies in either form. Eighteen octapeptides spanning the entire sequence of this region were synthesized on polyethylene pins, and epitopes of representative monoclonal antibodies were determined by ELISA. The reactivity of peptides suggest that a portion of the 25 mer peptide in AChE containing the active site serine is the primary epitope. It is not exposed on the surface of the enzyme and is most likely sequestered in a pocket-like conformation in the native enzyme.
ESTHER : Ogert_1990_J.Neurochem_55_756
PubMedSearch : Ogert_1990_J.Neurochem_55_756
PubMedID: 1696619

Title : Immunocytochemical localization of phosphatidylinositol-anchored acetylcholinesterase in excitable membranes of Torpedo ocellata - Eichler_1990_Brain.Res.Molecular.Brain.Research_8_213
Author(s) : Eichler J , Silman I , Gentry MK , Anglister L
Ref : Brain Research Mol Brain Res , 8 :213 , 1990
Abstract : In Torpedo electric organ much of the acetylcholinesterase is a 'globular' dimer (G2), anchored to the plasma membrane via covalently attached phosphatidylinositol and solubilized by a bacterial phosphatidylinositol-specific phospholipase C. This suggested that selective solubilization with phosphatidylinositol-specific phospholipase C, coupled with immunocytochemistry, might be used to localize G2 acetylcholinesterase in excitable tissues of Torpedo. Cryostat sections of electric organ, electromotor nerve, electric lobe and back muscle from Torpedo ocellata were labelled, using three different antibody preparations to Torpedo acetylcholinesterase, followed by a fluorescent second antibody, before and after exposure to the phospholipase. Sites of innervation on electrocytes and myofibers were labelled selectively, as were motor and electromotor nerves. In all these cases labelling was substantially diminished by prior exposure to the phospholipase. The results support our previous assignment, based on biochemical evidence, for a neuronal and synaptic localization of the G2 acetylcholinesterase in Torpedo. Electric lobe acetylcholinesterase appears insensitive to the phospholipase treatment and lacks certain epitopes present in both electric organ and electromotor nerve enzyme. This suggests that substantial processing of the G2 form occurs concomitantly with its movement from the electric lobe into the electromotor nerve.
ESTHER : Eichler_1990_Brain.Res.Molecular.Brain.Research_8_213
PubMedSearch : Eichler_1990_Brain.Res.Molecular.Brain.Research_8_213
PubMedID: 2170799

Title : Complete amino acid sequence of fetal bovine serum acetylcholinesterase and its comparison in various regions with other cholinesterases - Doctor_1990_FEBS.Lett_266_123
Author(s) : Doctor BP , Chapman TC , Christner CE , Deal CD , De La Hoz DM , Gentry MK , Ogert RA , Rush RS , Smyth KK , Wolfe AD
Ref : FEBS Letters , 266 :123 , 1990
Abstract : The complete amino acid sequence of a mammalian acetylcholinesterase from fetal bovine serum (FBS AChE) is presented. This enzyme has a high degree of sequence identity with other cholinesterases, liver carboxyesterases, esterase-6, lysophospholipase, and thyroglobulin. The locations of 191 amino acids in 10 regions of the FBS enzyme were compared with corresponding sequences of Torpedo, human, and Drosophila AChEs and human serum butyrylcholinesterase (BChE). In one region there is a marked difference in both the number of amino acids and their sequence between mammalian AChE and other AChEs and the human serum BChE. The amino acid sequence of FBS AChE showed overall homologies of 90% with human AChE, 60% with T. california AChE, 50% with human serum BChE, and 39% with Drosophila AChE in these regions.
ESTHER : Doctor_1990_FEBS.Lett_266_123
PubMedSearch : Doctor_1990_FEBS.Lett_266_123
PubMedID: 2365060
Gene_locus related to this paper: bovin-ACHE

Title : Structural and immunochemical properties of fetal bovine serum acetylcholinesterase -
Author(s) : Doctor BP , Smyth KK , Gentry MK , Ashani Y , Christner CE , De La Hoz DM , Ogert RA , Smith SW
Ref : Progress in Clinical & Biological Research , 289 :305 , 1989
PubMedID: 2471207

Title : Differences in structure and distribution of the molecular forms of acetylcholinesterase - Abramson_1989_J.Cell.Biol_108_2301
Author(s) : Abramson SN , Ellisman MH , Deerinck TJ , Maulet Y , Gentry MK , Doctor BP , Taylor P
Ref : Journal of Cell Biology , 108 :2301 , 1989
Abstract : Two structurally distinct molecular forms of acetylcholinesterase are found in the electric organs of Torpedo californica. One form is dimensionally asymmetric and composed of heterologous subunits. The other form is hydrophobic and composed of homologous subunits. Sequence-specific antibodies were raised against a synthetic peptide corresponding to the COOH-terminal region (Lys560-Leu575) of the catalytic subunits of the asymmetric form of acetylcholinesterase. These antibodies reacted with the asymmetric form of acetylcholinesterase, but not with the hydrophobic form. These results confirm recent studies suggesting that the COOH-terminal domain of the asymmetric form differs from that of the hydrophobic form, and represent the first demonstration of antibodies selective for the catalytic subunits of the asymmetric form. In addition, the reactive epitope of a monoclonal antibody (4E7), previously shown to be selective for the hydrophobic form of acetylcholinesterase, has been identified as an N-linked complex carbohydrate, thus defining posttranslational differences between the two forms. These two form-selective antibodies, as well as panselective polyclonal and monoclonal antibodies, were used in light and electron microscopic immunolocalization studies to investigate the distribution of the two forms of acetylcholinesterase in the electric organ of Torpedo. Both forms were localized almost exclusively to the innervated surface of the electrocytes. However, they were differentially distributed along the innervated surface. Specific asymmetric-form immunoreactivity was restricted to areas of synaptic apposition and to the invaginations of the postsynaptic membrane that form the synaptic gutters. In contrast, immunoreactivity attributable to the hydrophobic form was selectively found along the non-synaptic surface of the nerve terminals and was not observed in the synaptic cleft or in the invaginations of the postsynaptic membrane. This differential distribution suggests that the two forms of acetylcholinesterase may play different roles in regulating the local concentration of acetylcholine in the synapse.
ESTHER : Abramson_1989_J.Cell.Biol_108_2301
PubMedSearch : Abramson_1989_J.Cell.Biol_108_2301
PubMedID: 2472404

Title : Antigenic and structural differences in the catalytic subunits of the molecular forms of acetylcholinesterase - Doctor_1983_Proc.Natl.Acad.Sci.U.S.A_80_5767
Author(s) : Doctor BP , Camp S , Gentry MK , Taylor SS , Taylor P
Ref : Proceedings of the National Academy of Sciences of the United States of America , 80 :5767 , 1983
Abstract : A mixture of the 5.6S hydrophobic dimer and the asymmetric, tail-containing (17 + 13)S forms of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) from Torpedo californica was used to immunize mice, and spleen cells from these mice were used to produce nine hybridoma lines secreting antibodies against acetylcholinesterase. Antibodies from one of the lines showed a 100-fold greater affinity for the 5.6S species when compared with the catalytic subunits of the (17 + 13)S species. This difference in specificity was retained after denaturation of the two acetylcholinesterase species. Another line produced antibody directed only to structural subunits of the (17 + 13)S species, whereas the remaining seven antibodies exhibited nearly equivalent crossreactivity for all of the forms of acetylcholinesterase. Tryptic peptides were generated from the catalytic subunits of the 5.6S and tail-containing acetylcholinesterase species, and high-pressure liquid chromatographic profiles show at least two distinct peptides in the catalytic subunits for each enzyme species. Some of these peptides exhibit retention times different from those of the identified glycopeptides. Thus, it is likely that the catalytic subunits of two molecular forms of acetylcholinesterase differ in primary structure and sites of antigenicity.
ESTHER : Doctor_1983_Proc.Natl.Acad.Sci.U.S.A_80_5767
PubMedSearch : Doctor_1983_Proc.Natl.Acad.Sci.U.S.A_80_5767
PubMedID: 6193524