Sandbox UC 9

== Quaternary ligand binding to aromatic residues in the active-site gorge of acetylcholinesterase. ==

<Structure load='1pgb' size='300' frame='true' align='right' caption=' Torpedo acetylcholinesterase' scene='Insert optional scene name here' />

==Your Heading Here (maybe something like 'Structure')==<StructureSection load='1dq8' size='500' side='right' caption='Structure of HMG-CoA reductase (PDB entry [[1dq8]])' scene=''>PubMed Abstract:

Binding sites of Torpedo acetylcholinesterase (EC 3.1.1.7) for quaternary ligands were investigated by x-ray crystallography and photoaffinity labeling. Crystal structures of complexes with ligands were determined at 2.8-A resolution. In a complex with edrophonium, and quaternary nitrogen of the ligand interacts with the indole of Trp-84, and its m-hydroxyl displays bifurcated hydrogen bonding to two members of the catalytic triad, Ser-200 and His-440. In a complex with tacrine, the acridine is stacked against the indole of Trp-84. The bisquaternary ligand decamethonium is oriented along the narrow gorge leading to the active site; one quaternary group is apposed to the indole of Trp-84 and the other to that of Trp-279, near the top of the gorge. The only major conformational difference between the three complexes is in the orientation of the phenyl ring of Phe-330. In the decamethonium 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 by photoaffinity labelling by the photosensitive probe 3H-labeled p-(N,N-dimethylamino)benzenediazonium fluoroborate, which labeled, predominantly, Phe-330 within the active site. Labeling of Trp-279 was also observed. One mole of label is incorporated per mole of AcChoEase inactivated, indicating that labeling of Trp-279 and that of Phe-330 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 Trp-84 and Phe-330 to the "anionic" subsite of the active site and Trp-279 to the "peripheral" anionic site.</StructureSection>

[[Image:MW_Folding_Simulations.gif]]

<scene name='Sandbox_UC_9/Arcoiris2/2'>hermoso y desconocido </scene>

lalalala

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<Structure load='1acj' size='300' frame='true' align='center' caption='Insert caption here' scene='Insert optional scene name here' />

<scene name='Sandbox_UC_9/Tacrine/2'>escena nueva</scene>

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