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1gqr
From Proteopedia
| 1gqr, resolution 2.20Å () | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 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, 1gqs, 1hbj, 1oce, 1qid, 1qie, 1qif, 1qig, 1qih, 1qii, 1qij, 1qik, 1qim, 1qti, 1som, 1vot, 1vxo, 1vxr, 2ace, 2ack, 2dfp, 3ace, 4ace | ||||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
ACETYLCHOLINESTERASE (E.C. 3.1.1.7) COMPLEXED WITH RIVASTIGMINE
(see also AChE inhibitors and substrates (Part III)
Rivastigmine, a carbamate inhibitor of acetylcholinesterase, is already in use for treatment of Alzheimer's disease under the trade name of Exelon. Rivastigmine carbamylates Torpedo californica acetylcholinesterase very slowly (k(i) = 2.0 M(-1) min(-1)), whereas the bimolecular rate constant for inhibition of human acetylcholinesterase is >1600-fold higher (k(i) = 3300 M(-1) min(-1)). For human butyrylcholinesterase and for Drosophila melanogaster acetylcholinesterase, carbamylation is even more rapid (k(i) = 9 x 10(4) and 5 x 10(5) M(-1) min(-1), respectively). Spontaneous reactivation of all four conjugates is very slow, with <10% reactivation being observed for the Torpedo enzyme after 48 h. The crystal structure of the conjugate of rivastigmine with Torpedo acetylcholinesterase was determined to 2.2 A resolution. It revealed that the carbamyl moiety is covalently linked to the active-site serine, with the leaving group, (-)-S-3-[1-(dimethylamino)ethyl]phenol, being retained in the "anionic" site. A significant movement of the active-site histidine (H440) away from its normal hydrogen-bonded partner, E327, was observed, resulting in disruption of the catalytic triad. This movement may provide an explanation for the unusually slow kinetics of reactivation.
Kinetic and structural studies on the interaction of cholinesterases with the anti-Alzheimer drug rivastigmine., Bar-On P, Millard CB, Harel M, Dvir H, Enz A, Sussman JL, Silman I, Biochemistry. 2002 Mar 19;41(11):3555-64. PMID:11888271
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Rivastigmine (Exelon) is a carbamate inhibitor of AChE, and it is currenly used in therapy of Alzheimer's disease. Rivastigmine (colored yellow) interacts with TcAChE (colored lime) at the (1gqr). The carbamyl moiety of rivastigmine is to the active-site S200 Oγ. The second part of rivastigmine (the leaving group), NAP ((−)-S-3-[1-(dimethylamino)ethyl]phenol) is also held in the active-site gorge, but it is from the carbamyl moiety, hence, carbamylation took place. The of TcAChE/NAP (colored magenta) is known (1gqs). The TcAChE active-site residues which are interacting with NAP are colored violet. NAP is located in a similar region of TcAChE active site, but with different orientation than that of the NAP part (colored yellow) in the TcAChE/rivastigmine complex. Only H440 and F330 significantly change their side-chain conformations. of the TcAChE active sites in 4 different structures (TcAChE/rivastigmine (1gqr, yellow), TcAChE/NAP (1gqs), native TcAChE (2ace), and TcAChE/VX (1vxr, TcAChE colored white and VX black)) reveals that the conformation of H440 in the TcAChE/NAP structure is very similar its conformation in the native TcAChE (2ace), but the distance between H440 Nδ and E327 Oε is significantly longer in the TcAChE/rivastigmine and the TcAChE/VX complexes. This structural change disrupts the catalytic triad consisting of S200, E327, H440. This could explain the very slow kinetics of AChE reactivation after its inhibition by rivastigmine.
About this Structure
1GQR is a Single protein structure of sequence from Torpedo californica. Full crystallographic information is available from OCA.
Reference
Kinetic and structural studies on the interaction of cholinesterases with the anti-Alzheimer drug rivastigmine., Bar-On P, Millard CB, Harel M, Dvir H, Enz A, Sussman JL, Silman I, Biochemistry. 2002 Mar 19;41(11):3555-64. PMID:11888271
Page seeded by OCA on Tue Jul 1 05:55:05 2008
