Sandbox 12345

==Acetylcholinesterase in complex with tacrine==

<applet load='1acj' size='300' frame='true' align='right' caption='Insert caption here' />

In the crystal structure of Torpedo californica [[acetylcholinesterase]]

(TcAChE) complexed with tacrine (THA), THA's acridine ring is stacked

between the aromatic rings of <scene name='Sandbox_12345/1acj_x/1'>W84 and F330</scene>, near the catalytic triad

of AChE's active site which consists of S200, E327, H440. When

comparing 3 recent complexes of TcAChE, i.e. edrophonium (EDR),

decamethonium (DECA) and THA, the only major conformational difference

between them is seen in the orientation of the phenyl ring of F330. In

the DECA complex it lies parallel to the surface of the gorge; in the

other two complexes it is positioned to make contact with the bound

ligand. This close interaction was confirmed <ref>PMID:8415649</ref> by photoaffinity labeling

by a 3H-labeled photosensitive probe, which labeled, predominantly,

F330 within the active site. Labeling of W279 was also observed. One

mole of label is incorporated per mole of AChE inactivated, indicating

that labeling of W279 and that of F330 are mutually exclusive. The

structural and chemical data, together, show the important role of

aromatic groups as binding sites for quaternary ligands, and they

provide complementary evidence assigning W84 and F330 to the "anionic"

subsite of the active site and W279 to the "peripheral" anionic site.

<quiz display=simple>

{

|type="{}"}

Name a famous Greek philosopher.

{ Aristotle|Plato }

{Question

|type="[]"}

+ Correct answer.

- Incorrect answer.

+ Correct answer.

- Incorrect answer.

</quiz>

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