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2j3q
From Proteopedia
| 2j3q, resolution 2.80Å () | |||||||||
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| Sites: | , , , , and | ||||||||
| Ligands: | , , , | ||||||||
| Activity: | Acetylcholinesterase, with EC number 3.1.1.7 | ||||||||
| Related: | 1acj, 1acl, 1amn, 1ax9, 1cfj, 1dx6, 1e3q, 1e66, 1ea5, 1eea, 1eve, 1fss, 1gpk, 1gpn, 1gqr, 1gqs, 1h22, 1h23, 1hbj, 1jga, 1jgb, 1jjb, 1oce, 1odc, 1qid, 1qie, 1qif, 1qig, 1qih, 1qii, 1qij, 1qik, 1qim, 1qti, 1som, 1u65, 1ut6, 1vot, 1vxo, 1vxr, 1w4l, 1w6r, 1w75, 1w76, 1zgb, 1zgc, 2ace, 2ack, 2c4h, 2c58, 2c5f, 2c5g, 2cek, 2ckm, 2cmf, 2dfp, 2j3d, 3ace, 4ace | ||||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Contents |
TORPEDO ACETYLCHOLINESTERASE COMPLEXED WITH FLUOROPHORE THIOFLAVIN T
(see also AChE inhibitors and substrates (Part III))
Acetylcholinesterase plays a key role in cholinergic synaptic transmission by hydrolyzing the neurotransmitter acetylcholine with one of the highest known catalytic rate constants. Hydrolysis occurs in a narrow and deep gorge that contains two sites of ligand binding: A peripheral site, or P-site, near the gorge entrance that contributes to catalytic efficiency both by transiently trapping substrate molecules as they enter the gorge and by allosterically accelerating the transfer of the substrate acyl group to a serine hydroxyl in an acylation site or A-site at the base of the gorge. Thioflavin T is a useful reporter of ligand interactions with the A-site. It binds specifically to the P-site with fluorescence that is enhanced approximately 1000-fold over that of unbound thioflavin T, and the enhanced fluorescence is quenched 1.5- to 4-fold when another ligand binds to the A-site in a ternary complex. To clarify the structural basis of this advantageous signal change, we here report the X-ray structure of the complex of thioflavin T with Torpedo californica acetylcholinesterase. The two aromatic rings in thioflavin T are coplanar and are packed snugly parallel to the aromatic side chains of Trp279, Tyr334, and Phe330. Overlays of this structure with the crystal structures of Torpedo californica acetylcholinesterase complexes with either edrophonium or m-( N, N, N-trimethylammonio)-2,2,2-trifluoroacetophenone, two small aromatic ligands that bind specifically to the A-site, indicate that the phenyl side chain of Phe330 must rotate to sterically accommodate both thioflavin T and the A-site ligand in the ternary complex. This rotation may allow some relaxation of the strict coplanarity of the aromatic rings in the bound thioflavin T and result in partial quenching of its fluorescence.
Crystal structure of thioflavin T bound to the peripheral site of Torpedo californica acetylcholinesterase reveals how thioflavin T acts as a sensitive fluorescent reporter of ligand binding to the acylation site., Harel M, Sonoda LK, Silman I, Sussman JL, Rosenberry TL, J Am Chem Soc. 2008 Jun 25;130(25):7856-61. Epub 2008 May 31. PMID:18512913
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The Torpedo californica acetylcholinesterase (TcAChE) active site consists of two binding subsites. First of them is the "catalytic anionic site" (CAS), which involves catalytic triad (colored orange) and the conserved residues which also participate in ligands recognition. Another conserved residue (colored cyan) is situated at the second binding subsite, termed the "peripheral anionic site" (PAS), ~14 Å from CAS. is a good example of the PAS-binding AChE inhibitors. of the crystal structure of the CAS-binding inhibitor edrophonium in complex with TcAChE (2ack) on thioflavin T/TcAChE structure demonstrates that these ligands do not overlapped. Of note, that Phe330, which is part of the CAS, is a single residue interacting with thioflavin T. Only this residue significantly to avoid clashes in comparison to other CAS residues of the edrophonium/TcAChE complex.
About this Structure
2J3Q is a 1 chain structure of sequence from Torpedo californica. Full crystallographic information is available from OCA.
Additional Resources
For additional information, see: Alzheimer's Disease
Reference
- Harel M, Sonoda LK, Silman I, Sussman JL, Rosenberry TL. Crystal structure of thioflavin T bound to the peripheral site of Torpedo californica acetylcholinesterase reveals how thioflavin T acts as a sensitive fluorescent reporter of ligand binding to the acylation site. J Am Chem Soc. 2008 Jun 25;130(25):7856-61. Epub 2008 May 31. PMID:18512913 doi:10.1021/ja7109822
Page seeded by OCA on Mon Feb 16 21:37:00 2009
Categories: Acetylcholinesterase | Torpedo californica | Cusack, B. | Harel, M. | Johnson, J L. | Rosenberry, T L. | Silman, I. | Sussman, J L. | Alternative splicing | Anticancer prodrug cpt- 11 | Glycoprotein | Gpi-anchor | Hydrolase | Lipoprotein | Membrane | Neurotransmitter degradation | Serine esterase | Synapse | Torpedo ache
