Skip to main content
PMC home page
Biophysical Journal logoLink to Biophysical Journal
. 1999 Nov;77(5):2430–2450. doi: 10.1016/S0006-3495(99)77080-3

A modular treatment of molecular traffic through the active site of cholinesterase

SA Botti 1, CE Felder 1, S Lifson 1, JL Sussman 1, I Silman I 1
PMCID: PMC1300520  PMID: 10545346

Abstract

We present a model for the molecular traffic of ligands, substrates, and products through the active site of cholinesterases (ChEs). First, we describe a common treatment of the diffusion to a buried active site of cationic and neutral species. We then explain the specificity of ChEs for cationic ligands and substrates by introducing two additional components to this common treatment. The first module is a surface trap for cationic species at the entrance to the active-site gorge that operates through local, short-range electrostatic interactions and is independent of ionic strength. The second module is an ionic-strength-dependent steering mechanism generated by long-range electrostatic interactions arising from the overall distribution of charges in ChEs. Our calculations show that diffusion of charged ligands relative to neutral isosteric analogs is enhanced approximately 10-fold by the surface trap, while electrostatic steering contributes only a 1.5- to 2-fold rate enhancement at physiological salt concentration. We model clearance of cationic products from the active-site gorge as analogous to the escape of a particle from a one-dimensional well in the presence of a linear electrostatic potential. We evaluate the potential inside the gorge and provide evidence that while contributing to the steering of cationic species toward the active site, it does not appreciably retard their clearance. This optimal fine-tuning of global and local electrostatic interactions endows ChEs with maximum catalytic efficiency and specificity for a positively charged substrate, while at the same time not hindering clearance of the positively charged products.

Full Text

The Full Text of this article is available as a PDF (726.1 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Allen K. N., Abeles R. H. Inhibition kinetics of acetylcholinesterase with fluoromethyl ketones. Biochemistry. 1989 Oct 17;28(21):8466–8473. doi: 10.1021/bi00447a029. [DOI] [PubMed] [Google Scholar]
  2. Allen K. N., Abeles R. H. Inhibition of pig liver esterase by trifluoromethyl ketones: modulators of the catalytic reaction alter inhibition kinetics. Biochemistry. 1989 Jan 10;28(1):135–140. doi: 10.1021/bi00427a020. [DOI] [PubMed] [Google Scholar]
  3. Altschul S. F., Gish W., Miller W., Myers E. W., Lipman D. J. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. doi: 10.1016/S0022-2836(05)80360-2. [DOI] [PubMed] [Google Scholar]
  4. Anthony N., Rocheleau T., Mocelin G., Lee H. J., ffrench-Constant R. Cloning, sequencing and functional expression of an acetylcholinesterase gene from the yellow fever mosquito Aedes aegypti. FEBS Lett. 1995 Jul 24;368(3):461–465. doi: 10.1016/0014-5793(95)00711-h. [DOI] [PubMed] [Google Scholar]
  5. Antosiewicz J., Gilson M. K., Lee I. H., McCammon J. A. Acetylcholinesterase: diffusional encounter rate constants for dumbbell models of ligand. Biophys J. 1995 Jan;68(1):62–68. doi: 10.1016/S0006-3495(95)80159-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Antosiewicz J., McCammon J. A. Electrostatic and hydrodynamic orientational steering effects in enzyme-substrate association. Biophys J. 1995 Jul;69(1):57–65. doi: 10.1016/S0006-3495(95)79874-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Antosiewicz J., McCammon J. A., Wlodek S. T., Gilson M. K. Simulation of charge-mutant acetylcholinesterases. Biochemistry. 1995 Apr 4;34(13):4211–4219. doi: 10.1021/bi00013a009. [DOI] [PubMed] [Google Scholar]
  8. Antosiewicz J., Wlodek S. T., McCammon J. A. Acetylcholinesterase: role of the enzyme's charge distribution in steering charged ligands toward the active site. Biopolymers. 1996 Jul;39(1):85–94. doi: 10.1002/(SICI)1097-0282(199607)39:1%3C85::AID-BIP9%3E3.0.CO;2-R. [DOI] [PubMed] [Google Scholar]
  9. BERGMANN F., WILSON I. B., NACHMANSOHN D. The inhibitory effect of stilbamidine, curare and related compounds and its relationship to the active groups of acetylcholine esterase; action of stilbamidine upon nerve impulse conduction. Biochim Biophys Acta. 1950 Sep;6(1):217–224. doi: 10.1016/0006-3002(50)90094-1. [DOI] [PubMed] [Google Scholar]
  10. Barak D., Ordentlich A., Bromberg A., Kronman C., Marcus D., Lazar A., Ariel N., Velan B., Shafferman A. Allosteric modulation of acetylcholinesterase activity by peripheral ligands involves a conformational transition of the anionic subsite. Biochemistry. 1995 Nov 28;34(47):15444–15452. doi: 10.1021/bi00047a008. [DOI] [PubMed] [Google Scholar]
  11. Bartolucci C., Perola E., Cellai L., Brufani M., Lamba D. "Back door" opening implied by the crystal structure of a carbamoylated acetylcholinesterase. Biochemistry. 1999 May 4;38(18):5714–5719. doi: 10.1021/bi982723p. [DOI] [PubMed] [Google Scholar]
  12. Bataillé S., Portalier P., Coulon P., Ternaux J. P. Influence of acetylcholinesterase on embryonic spinal rat motoneurones growth in culture: a quantitative morphometric study. Eur J Neurosci. 1998 Feb;10(2):560–572. doi: 10.1046/j.1460-9568.1998.00065.x. [DOI] [PubMed] [Google Scholar]
  13. Bazelyansky M., Robey E., Kirsch J. F. Fractional diffusion-limited component of reactions catalyzed by acetylcholinesterase. Biochemistry. 1986 Jan 14;25(1):125–130. doi: 10.1021/bi00349a019. [DOI] [PubMed] [Google Scholar]
  14. Bhanumathy C. D., Balasubramanian A. S. Evidence for a Zn(2+)-binding site in human serum butyrylcholinesterase. Biochem J. 1996 Apr 1;315(Pt 1):127–131. doi: 10.1042/bj3150127. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Bourne Y., Taylor P., Marchot P. Acetylcholinesterase inhibition by fasciculin: crystal structure of the complex. Cell. 1995 Nov 3;83(3):503–512. doi: 10.1016/0092-8674(95)90128-0. [DOI] [PubMed] [Google Scholar]
  16. Brady K., Liang T. C., Abeles R. H. pH dependence of the inhibition of chymotrypsin by a peptidyl trifluoromethyl ketone. Biochemistry. 1989 Nov 14;28(23):9066–9070. doi: 10.1021/bi00449a017. [DOI] [PubMed] [Google Scholar]
  17. Changeux J. P. Responses of acetylcholinesterase from Torpedo marmorata to salts and curarizing drugs. Mol Pharmacol. 1966 Sep;2(5):369–392. [PubMed] [Google Scholar]
  18. Chatonnet A., Lockridge O. Comparison of butyrylcholinesterase and acetylcholinesterase. Biochem J. 1989 Jun 15;260(3):625–634. doi: 10.1042/bj2600625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Cousin X., Hotelier T., Giles K., Lievin P., Toutant J. P., Chatonnet A. The alpha/beta fold family of proteins database and the cholinesterase gene server ESTHER. Nucleic Acids Res. 1997 Jan 1;25(1):143–146. doi: 10.1093/nar/25.1.143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Dawson R. M., Crone H. D. Inorganic ion effects on the kinetic parameters of acetylcholinesterase. J Neurochem. 1973 Jul;21(1):247–249. doi: 10.1111/j.1471-4159.1973.tb04245.x. [DOI] [PubMed] [Google Scholar]
  21. Dougherty D. A. Cation-pi interactions in chemistry and biology: a new view of benzene, Phe, Tyr, and Trp. Science. 1996 Jan 12;271(5246):163–168. doi: 10.1126/science.271.5246.163. [DOI] [PubMed] [Google Scholar]
  22. Dougherty D. A., Stauffer D. A. Acetylcholine binding by a synthetic receptor: implications for biological recognition. Science. 1990 Dec 14;250(4987):1558–1560. doi: 10.1126/science.2274786. [DOI] [PubMed] [Google Scholar]
  23. Eriksson H., Augustinsson K. B. A mechanistic model for butyrylcholinesterase. Biochim Biophys Acta. 1979 Mar 16;567(1):161–173. doi: 10.1016/0005-2744(79)90183-9. [DOI] [PubMed] [Google Scholar]
  24. Faerman C., Ripoll D., Bon S., Le Feuvre Y., Morel N., Massoulié J., Sussman J. L., Silman I. Site-directed mutants designed to test back-door hypotheses of acetylcholinesterase function. FEBS Lett. 1996 May 13;386(1):65–71. doi: 10.1016/0014-5793(96)00374-2. [DOI] [PubMed] [Google Scholar]
  25. Felder C. E., Botti S. A., Lifson S., Silman I., Sussman J. L. External and internal electrostatic potentials of cholinesterase models. J Mol Graph Model. 1997 Oct;15(5):318-27, 335-7. doi: 10.1016/s1093-3263(98)00005-9. [DOI] [PubMed] [Google Scholar]
  26. Gilson M. K., Honig B. Calculation of the total electrostatic energy of a macromolecular system: solvation energies, binding energies, and conformational analysis. Proteins. 1988;4(1):7–18. doi: 10.1002/prot.340040104. [DOI] [PubMed] [Google Scholar]
  27. Gilson M. K., Straatsma T. P., McCammon J. A., Ripoll D. R., Faerman C. H., Axelsen P. H., Silman I., Sussman J. L. Open "back door" in a molecular dynamics simulation of acetylcholinesterase. Science. 1994 Mar 4;263(5151):1276–1278. doi: 10.1126/science.8122110. [DOI] [PubMed] [Google Scholar]
  28. Grauso M., Culetto E., Combes D., Fedon Y., Toutant J. P., Arpagaus M. Existence of four acetylcholinesterase genes in the nematodes Caenorhabditis elegans and Caenorhabditis briggsae. FEBS Lett. 1998 Mar 13;424(3):279–284. doi: 10.1016/s0014-5793(98)00191-4. [DOI] [PubMed] [Google Scholar]
  29. Harel M., Kleywegt G. J., Ravelli R. B., Silman I., Sussman J. L. Crystal structure of an acetylcholinesterase-fasciculin complex: interaction of a three-fingered toxin from snake venom with its target. Structure. 1995 Dec 15;3(12):1355–1366. doi: 10.1016/s0969-2126(01)00273-8. [DOI] [PubMed] [Google Scholar]
  30. Harel M., Schalk I., Ehret-Sabatier L., Bouet F., Goeldner M., Hirth C., Axelsen P. H., Silman I., Sussman J. L. Quaternary ligand binding to aromatic residues in the active-site gorge of acetylcholinesterase. Proc Natl Acad Sci U S A. 1993 Oct 1;90(19):9031–9035. doi: 10.1073/pnas.90.19.9031. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Hasan F. B., Elkind J. L., Cohen S. G., Cohen J. B. Cationic and uncharged substrates and reversible inhibitors in hydrolysis by acetylcholinesterase (EC 3.1.1.7). The trimethyl subsite. J Biol Chem. 1981 Aug 10;256(15):7781–7785. [PubMed] [Google Scholar]
  32. Hasinoff B. B. Kinetics of acetylthiocholine binding to electric eel acetylcholinesterase in glycerol/water solvents of increased viscosity. Evidence for a diffusion-controlled reaction. Biochim Biophys Acta. 1982 May 21;704(1):52–58. doi: 10.1016/0167-4838(82)90131-5. [DOI] [PubMed] [Google Scholar]
  33. Hofer P., Fringeli U. P., Hopff W. H. Activation of acetylcholinesterase by monovalent (Na+,K+) and divalent (Ca2+,Mg2+) cations. Biochemistry. 1984 Jun 5;23(12):2730–2734. doi: 10.1021/bi00307a030. [DOI] [PubMed] [Google Scholar]
  34. Honig B., Nicholls A. Classical electrostatics in biology and chemistry. Science. 1995 May 26;268(5214):1144–1149. doi: 10.1126/science.7761829. [DOI] [PubMed] [Google Scholar]
  35. Hosea N. A., Radić Z., Tsigelny I., Berman H. A., Quinn D. M., Taylor P. Aspartate 74 as a primary determinant in acetylcholinesterase governing specificity to cationic organophosphonates. Biochemistry. 1996 Aug 20;35(33):10995–11004. doi: 10.1021/bi9611220. [DOI] [PubMed] [Google Scholar]
  36. Imperiali B., Abeles R. H. Inhibition of serine proteases by peptidyl fluoromethyl ketones. Biochemistry. 1986 Jul 1;25(13):3760–3767. doi: 10.1021/bi00361a005. [DOI] [PubMed] [Google Scholar]
  37. Inestrosa N. C., Alvarez A., Pérez C. A., Moreno R. D., Vicente M., Linker C., Casanueva O. I., Soto C., Garrido J. Acetylcholinesterase accelerates assembly of amyloid-beta-peptides into Alzheimer's fibrils: possible role of the peripheral site of the enzyme. Neuron. 1996 Apr;16(4):881–891. doi: 10.1016/s0896-6273(00)80108-7. [DOI] [PubMed] [Google Scholar]
  38. Jackson S. E., Fersht A. R. Contribution of long-range electrostatic interactions to the stabilization of the catalytic transition state of the serine protease subtilisin BPN'. Biochemistry. 1993 Dec 21;32(50):13909–13916. doi: 10.1021/bi00213a021. [DOI] [PubMed] [Google Scholar]
  39. Jones S. A., Holmes C., Budd T. C., Greenfield S. A. The effect of acetylcholinesterase on outgrowth of dopaminergic neurons in organotypic slice culture of rat mid-brain. Cell Tissue Res. 1995 Feb;279(2):323–330. doi: 10.1007/BF00318488. [DOI] [PubMed] [Google Scholar]
  40. KRUPKA R. M. The mechanism of action of acetylcholinesterase: substrate inhibition and the binding of inhibitors. Biochemistry. 1963 Jan-Feb;2:76–82. doi: 10.1021/bi00901a015. [DOI] [PubMed] [Google Scholar]
  41. Karlsson E., Mbugua P. M., Rodriguez-Ithurralde D. Fasciculins, anticholinesterase toxins from the venom of the green mamba Dendroaspis angusticeps. J Physiol (Paris) 1984;79(4):232–240. [PubMed] [Google Scholar]
  42. Kronman C., Ordentlich A., Barak D., Velan B., Shafferman A. The "back door" hypothesis for product clearance in acetylcholinesterase challenged by site-directed mutagenesis. J Biol Chem. 1994 Nov 11;269(45):27819–27822. [PubMed] [Google Scholar]
  43. Layer P. G., Weikert T., Alber R. Cholinesterases regulate neurite growth of chick nerve cells in vitro by means of a non-enzymatic mechanism. Cell Tissue Res. 1993 Aug;273(2):219–226. doi: 10.1007/BF00312823. [DOI] [PubMed] [Google Scholar]
  44. Masson P., Froment M. T., Bartels C. F., Lockridge O. Asp7O in the peripheral anionic site of human butyrylcholinesterase. Eur J Biochem. 1996 Jan 15;235(1-2):36–48. doi: 10.1111/j.1432-1033.1996.00036.x. [DOI] [PubMed] [Google Scholar]
  45. Masson P., Legrand P., Bartels C. F., Froment M. T., Schopfer L. M., Lockridge O. Role of aspartate 70 and tryptophan 82 in binding of succinyldithiocholine to human butyrylcholinesterase. Biochemistry. 1997 Feb 25;36(8):2266–2277. doi: 10.1021/bi962484a. [DOI] [PubMed] [Google Scholar]
  46. Massoulié J., Pezzementi L., Bon S., Krejci E., Vallette F. M. Molecular and cellular biology of cholinesterases. Prog Neurobiol. 1993 Jul;41(1):31–91. doi: 10.1016/0301-0082(93)90040-y. [DOI] [PubMed] [Google Scholar]
  47. Mendel B., Rudney H. Studies on cholinesterase: 1. Cholinesterase and pseudo-cholinesterase. Biochem J. 1943 Apr;37(1):59–63. doi: 10.1042/bj0370059. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Mutero A., Pralavorio M., Simeon V., Fournier D. Catalytic properties of cholinesterases: importance of tyrosine 109 in Drosophila protein. Neuroreport. 1992 Jan;3(1):39–42. doi: 10.1097/00001756-199201000-00010. [DOI] [PubMed] [Google Scholar]
  49. Nair H. K., Seravalli J., Arbuckle T., Quinn D. M. Molecular recognition in acetylcholinesterase catalysis: free-energy correlations for substrate turnover and inhibition by trifluoro ketone transition-state analogs. Biochemistry. 1994 Jul 19;33(28):8566–8576. doi: 10.1021/bi00194a023. [DOI] [PubMed] [Google Scholar]
  50. Nolte H. J., Rosenberry T. L., Neumann E. Effective charge on acetylcholinesterase active sites determined from the ionic strength dependence of association rate constants with cationic ligands. Biochemistry. 1980 Aug 5;19(16):3705–3711. doi: 10.1021/bi00557a011. [DOI] [PubMed] [Google Scholar]
  51. Ordentlich A., Barak D., Kronman C., Ariel N., Segall Y., Velan B., Shafferman A. The architecture of human acetylcholinesterase active center probed by interactions with selected organophosphate inhibitors. J Biol Chem. 1996 May 17;271(20):11953–11962. doi: 10.1074/jbc.271.20.11953. [DOI] [PubMed] [Google Scholar]
  52. Ordentlich A., Barak D., Kronman C., Flashner Y., Leitner M., Segall Y., Ariel N., Cohen S., Velan B., Shafferman A. Dissection of the human acetylcholinesterase active center determinants of substrate specificity. Identification of residues constituting the anionic site, the hydrophobic site, and the acyl pocket. J Biol Chem. 1993 Aug 15;268(23):17083–17095. [PubMed] [Google Scholar]
  53. Peitsch M. C. ProMod and Swiss-Model: Internet-based tools for automated comparative protein modelling. Biochem Soc Trans. 1996 Feb;24(1):274–279. doi: 10.1042/bst0240274. [DOI] [PubMed] [Google Scholar]
  54. Porschke D., Créminon C., Cousin X., Bon C., Sussman J., Silman I. Electrooptical measurements demonstrate a large permanent dipole moment associated with acetylcholinesterase. Biophys J. 1996 Apr;70(4):1603–1608. doi: 10.1016/S0006-3495(96)79759-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Radić Z., Kirchhoff P. D., Quinn D. M., McCammon J. A., Taylor P. Electrostatic influence on the kinetics of ligand binding to acetylcholinesterase. Distinctions between active center ligands and fasciculin. J Biol Chem. 1997 Sep 12;272(37):23265–23277. doi: 10.1074/jbc.272.37.23265. [DOI] [PubMed] [Google Scholar]
  56. Radić Z., Pickering N. A., Vellom D. C., Camp S., Taylor P. Three distinct domains in the cholinesterase molecule confer selectivity for acetyl- and butyrylcholinesterase inhibitors. Biochemistry. 1993 Nov 16;32(45):12074–12084. doi: 10.1021/bi00096a018. [DOI] [PubMed] [Google Scholar]
  57. Radić Z., Quinn D. M., Vellom D. C., Camp S., Taylor P. Allosteric control of acetylcholinesterase catalysis by fasciculin. J Biol Chem. 1995 Sep 1;270(35):20391–20399. doi: 10.1074/jbc.270.35.20391. [DOI] [PubMed] [Google Scholar]
  58. Radić Z., Reiner E., Taylor P. Role of the peripheral anionic site on acetylcholinesterase: inhibition by substrates and coumarin derivatives. Mol Pharmacol. 1991 Jan;39(1):98–104. [PubMed] [Google Scholar]
  59. Ripoll D. R., Faerman C. H., Axelsen P. H., Silman I., Sussman J. L. An electrostatic mechanism for substrate guidance down the aromatic gorge of acetylcholinesterase. Proc Natl Acad Sci U S A. 1993 Jun 1;90(11):5128–5132. doi: 10.1073/pnas.90.11.5128. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Rosenberry T. L. Acetylcholinesterase. Adv Enzymol Relat Areas Mol Biol. 1975;43:103–218. doi: 10.1002/9780470122884.ch3. [DOI] [PubMed] [Google Scholar]
  61. Rosenberry T. L. Catalysis by acetylcholinesterase: evidence that the rate-limiting step for acylation with certain substrates precedes general acid-base catalysis. Proc Natl Acad Sci U S A. 1975 Oct;72(10):3834–3838. doi: 10.1073/pnas.72.10.3834. [DOI] [PMC free article] [PubMed] [Google Scholar]
  62. Rosenberry T. L., Neumann E. Interaction of ligands with acetylcholinesterase. Use of temperature-jump relaxation kinetics in the binding of specific fluorescent ligands. Biochemistry. 1977 Aug 23;16(17):3870–3878. doi: 10.1021/bi00636a024. [DOI] [PubMed] [Google Scholar]
  63. Shafferman A., Ordentlich A., Barak D., Kronman C., Ber R., Bino T., Ariel N., Osman R., Velan B. Electrostatic attraction by surface charge does not contribute to the catalytic efficiency of acetylcholinesterase. EMBO J. 1994 Aug 1;13(15):3448–3455. doi: 10.1002/j.1460-2075.1994.tb06650.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Shafferman A., Velan B., Ordentlich A., Kronman C., Grosfeld H., Leitner M., Flashner Y., Cohen S., Barak D., Ariel N. Substrate inhibition of acetylcholinesterase: residues affecting signal transduction from the surface to the catalytic center. EMBO J. 1992 Oct;11(10):3561–3568. doi: 10.1002/j.1460-2075.1992.tb05439.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  65. Smissaert H. R. Acetylcholinesterase: evidence that sodium ion binding at the anionic site causes inhibition of the second-order hydrolysis of acetylcholine and a decrease of its pKa as well as of deacetylation. Biochem J. 1981 Jul 1;197(1):163–170. doi: 10.1042/bj1970163. [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Srivatsan M., Peretz B. Acetylcholinesterase promotes regeneration of neurites in cultured adult neurons of Aplysia. Neuroscience. 1997 Apr;77(3):921–931. doi: 10.1016/s0306-4522(96)00458-7. [DOI] [PubMed] [Google Scholar]
  67. Stauffer D. A., Karlin A. Electrostatic potential of the acetylcholine binding sites in the nicotinic receptor probed by reactions of binding-site cysteines with charged methanethiosulfonates. Biochemistry. 1994 Jun 7;33(22):6840–6849. doi: 10.1021/bi00188a013. [DOI] [PubMed] [Google Scholar]
  68. Sussman J. L., Harel M., Frolow F., Oefner C., Goldman A., Toker L., Silman I. Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein. Science. 1991 Aug 23;253(5022):872–879. doi: 10.1126/science.1678899. [DOI] [PubMed] [Google Scholar]
  69. Takahashi L. H., Radhakrishnan R., Rosenfield R. E., Jr, Meyer E. F., Jr, Trainor D. A., Stein M. X-ray diffraction analysis of the inhibition of porcine pancreatic elastase by a peptidyl trifluoromethylketone. J Mol Biol. 1988 May 20;201(2):423–428. doi: 10.1016/0022-2836(88)90148-9. [DOI] [PubMed] [Google Scholar]
  70. Tan R. C., Truong T. N., McCammon J. A., Sussman J. L. Acetylcholinesterase: electrostatic steering increases the rate of ligand binding. Biochemistry. 1993 Jan 19;32(2):401–403. doi: 10.1021/bi00053a003. [DOI] [PubMed] [Google Scholar]
  71. Taylor P., Lappi S. Interaction of fluorescence probes with acetylcholinesterase. The site and specificity of propidium binding. Biochemistry. 1975 May 6;14(9):1989–1997. doi: 10.1021/bi00680a029. [DOI] [PubMed] [Google Scholar]
  72. Taylor P., Radić Z. The cholinesterases: from genes to proteins. Annu Rev Pharmacol Toxicol. 1994;34:281–320. doi: 10.1146/annurev.pa.34.040194.001433. [DOI] [PubMed] [Google Scholar]
  73. Toutant J. P. Insect acetylcholinesterase: catalytic properties, tissue distribution and molecular forms. Prog Neurobiol. 1989;32(5):423–446. doi: 10.1016/0301-0082(89)90031-2. [DOI] [PubMed] [Google Scholar]
  74. Vellom D. C., Radić Z., Li Y., Pickering N. A., Camp S., Taylor P. Amino acid residues controlling acetylcholinesterase and butyrylcholinesterase specificity. Biochemistry. 1993 Jan 12;32(1):12–17. doi: 10.1021/bi00052a003. [DOI] [PubMed] [Google Scholar]
  75. WILSON I. B., ALEXANDER J. Acetylcholinesterase: reversible inhibitors, substrate inhibition. J Biol Chem. 1962 Apr;237:1323–1326. [PubMed] [Google Scholar]
  76. WILSON I. B., BERGMANN F. Studies on cholinesterase. VII. The active surface of acetylcholine esterase derived from effects of pH on inhibitors. J Biol Chem. 1950 Aug;185(2):479–489. [PubMed] [Google Scholar]
  77. Warwicker J., Watson H. C. Calculation of the electric potential in the active site cleft due to alpha-helix dipoles. J Mol Biol. 1982 Jun 5;157(4):671–679. doi: 10.1016/0022-2836(82)90505-8. [DOI] [PubMed] [Google Scholar]
  78. Willbold E., Layer P. G. Butyrylcholinesterase regulates laminar retinogenesis of the chick embryo in vitro. Eur J Cell Biol. 1994 Jun;64(1):192–199. [PubMed] [Google Scholar]
  79. Zhou H. X., Wlodek S. T., McCammon J. A. Conformation gating as a mechanism for enzyme specificity. Proc Natl Acad Sci U S A. 1998 Aug 4;95(16):9280–9283. doi: 10.1073/pnas.95.16.9280. [DOI] [PMC free article] [PubMed] [Google Scholar]
  80. Zhu K. Y., Clark J. M. Cloning and sequencing of a cDNA encoding acetylcholinesterase in Colorado potato beetle, Leptinotarsa decemlineata (Say). Insect Biochem Mol Biol. 1995 Dec;25(10):1129–1138. doi: 10.1016/0965-1748(95)00055-0. [DOI] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES