Publication Date:
1991-08-23
Description:
The three-dimensional structure of acetylcholinesterase from Torpedo californica electric organ has been determined by x-ray analysis to 2.8 angstrom resolution. The form crystallized is the glycolipid-anchored homodimer that was purified subsequent to solubilization with a bacterial phosphatidylinositol-specific phospholipase C. The enzyme monomer is an alpha/beta protein that contains 537 amino acids. It consists of a 12-stranded mixed beta sheet surrounded by 14 alpha helices and bears a striking resemblance to several hydrolase structures including dienelactone hydrolase, serine carboxypeptidase-II, three neutral lipases, and haloalkane dehalogenase. The active site is unusual because it contains Glu, not Asp, in the Ser-His-acid catalytic triad and because the relation of the triad to the rest of the protein approximates a mirror image of that seen in the serine proteases. Furthermore, the active site lies near the bottom of a deep and narrow gorge that reaches halfway into the protein. Modeling of acetylcholine binding to the enzyme suggests that the quaternary ammonium ion is bound not to a negatively charged "anionic" site, but rather to some of the 14 aromatic residues that line the gorge.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sussman, J L -- Harel, M -- Frolow, F -- Oefner, C -- Goldman, A -- Toker, L -- Silman, I -- New York, N.Y. -- Science. 1991 Aug 23;253(5022):872-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Structural Chemistry, Weizmann Institute of Science, Rehovot, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1678899" target="_blank"〉PubMed〈/a〉
Keywords:
Acetylcholine/*metabolism
;
Acetylcholinesterase/*chemistry/metabolism
;
Amino Acid Sequence
;
Animals
;
Binding Sites
;
Cell Membrane/enzymology
;
Chemistry, Physical
;
Crystallization
;
Electric Organ/*enzymology
;
Glutamates
;
Glutamic Acid
;
Macromolecular Substances
;
Molecular Sequence Data
;
Molecular Structure
;
Phosphatidylinositols/metabolism
;
Physicochemical Phenomena
;
Protein Conformation
;
Sequence Homology, Nucleic Acid
;
*Torpedo
;
X-Ray Diffraction
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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