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| ==Acetylcholinesterase in complex with tacrine==
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| <applet load='1acj' size='300' frame='true' align='right' caption='Insert caption here' />
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| In the crystal structure of Torpedo californica [[acetylcholinesterase]]
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| (TcAChE) complexed with tacrine (THA), THA's acridine ring is stacked
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| between the aromatic rings of <scene name='Sandbox_12345/1acj_x/1'>W84 and F330</scene>, near the catalytic triad
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| of AChE's active site which consists of S200, E327, H440. When
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| comparing 3 recent complexes of TcAChE, i.e. edrophonium (EDR),
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| decamethonium (DECA) and THA, the only major conformational difference
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| between them is seen in the orientation of the phenyl ring of F330. In
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| the DECA complex it lies parallel to the surface of the gorge; in the
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| other two complexes it is positioned to make contact with the bound
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| ligand. This close interaction was confirmed <ref>PMID:8415649</ref> by photoaffinity labeling
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| by a 3H-labeled photosensitive probe, which labeled, predominantly,
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| F330 within the active site. Labeling of W279 was also observed. One
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| mole of label is incorporated per mole of AChE inactivated, indicating
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| that labeling of W279 and that of F330 are mutually exclusive. The
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| structural and chemical data, together, show the important role of
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| aromatic groups as binding sites for quaternary ligands, and they
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| provide complementary evidence assigning W84 and F330 to the "anionic"
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| subsite of the active site and W279 to the "peripheral" anionic site.
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| <quiz display=simple>
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| {
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| |type="{}"}
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| Name a famous Greek philosopher.
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| { Aristotle|Plato }
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| {Question
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| |type="[]"}
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| + Correct answer.
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| - Incorrect answer.
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| + Correct answer.
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| - Incorrect answer.
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| </quiz>
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| <references/>
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