First time at Proteopedia? Click on the green links: they change the 3D image. Click and drag the molecules. Proteopedia is a 3D, interactive encyclopedia of proteins, RNA, DNA and other molecules. With a free user account, you can edit pages in Proteopedia. Visit the Main Page to learn more.
1h23
From Proteopedia
| 1h23, resolution 2.15Å () | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 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, 1hbj, 1h22, 1jjb, 1oce, 1qid, 1qie, 1qif, 1qig, 1qih, 1qii, 1qij, 1qik, 1qim, 1qti, 1som, 1vot, 1vxo, 1vxr, 2ace, 2ack, 2dfp, 3ace, 4ace | ||||||||
| |||||||||
| |||||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Contents |
STRUCTURE OF ACETYLCHOLINESTERASE (E.C. 3.1.1.7) COMPLEXED WITH (S,S)-(-)-BIS(12)-HUPYRIDONE AT 2.15A RESOLUTION
(see also AChE bivalent inhibitors, 1h22, 1zgb, and 1zgc)
Acetylcholinesterase (AChE) inhibitors improve the cognitive abilities of Alzheimer patients. (-)-Huperzine A [(-)-HupA], an alkaloid isolated from the club moss, Huperzia serrata, is one such inhibitor, but the search for more potent and selective drugs continues. Recently, alkylene-linked dimers of 5-amino-5,6,7,8-tetrahydroquinolinone (hupyridone, 1a), a fragment of HupA, were shown to serve as more potent inhibitors of AChE than (-)-HupA and monomeric 1a. We soaked two such dimers, (S,S)-(-)-bis(10)-hupyridone [(S,S)-(-)-2a] and (S,S)-(-)-bis(12)-hupyridone [(S,S)-(-)-2b] containing, respectively, 10 and 12 methylenes in the spacer, into trigonal TcAChE crystals, and solved the X-ray structures of the resulting complexes using the difference Fourier technique, both to 2.15 A resolution. The structures revealed one HupA-like 1a unit bound to the "anionic" subsite of the active-site, near the bottom of the active-site gorge, adjacent to Trp84, as seen for the TcAChE/(-)-HupA complex, and the second 1a unit near Trp279 in the "peripheral" anionic site at the top of the gorge, both bivalent molecules thus spanning the active-site gorge. The results confirm that the increased affinity of the dimeric HupA analogues for AChE is conferred by binding to the two "anionic" sites of the enzyme. Inhibition data show that (-)-2a binds to TcAChE approximately 6-7- and > 170-fold more tightly than (-)-2b and (-)-HupA, respectively. In contrast, previous data for rat AChE show that (-)-2b binds approximately 3- and approximately 2-fold more tightly than (-)-2a and (-)-HupA, respectively. Structural comparison of TcAChE with rat AChE, as represented by the closely related mouse AChE structure (1maa.pdb), reveals a narrower gorge for rat AChE, a perpendicular alignment of the Tyr337 ring to the gorge axis, and its conformational rigidity, as a result of hydrogen bonding between its hydroxyl group and that of Tyr341, relative to TcAChE Phe330. These structural differences in the active-site gorge explain the switch in inhibitory potency of (-)-2a and 2b and the larger dimer/(-)-HupA potency ratios observed for TcAChE relative to rat AChE. The results offer new insights into factors affecting protein-ligand complementarity within the gorge and should assist the further development of improved AChE inhibitors.
Acetylcholinesterase complexed with bivalent ligands related to huperzine a: experimental evidence for species-dependent protein-ligand complementarity., Wong DM, Greenblatt HM, Dvir H, Carlier PR, Han YF, Pang YP, Silman I, Sussman JL, J Am Chem Soc. 2003 Jan 15;125(2):363-73. PMID:12517147
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
of the complexes of (R)-tacrine-(10)-hupyridone ((R)-3, cyan, PDB entry 1zgb) and (S,S)-(-)-Bis(12)-hupyridone ((S,S)-(-)-4b, orange, i.e. 12-carbon-tether-linked hupyridone dimer, 1h23) and (S,S)-(-)-Bis(10)-hupyridone ((S,S)-(-)-4a, plum, 1h22) with TcAChE demonstrates the binding mode of the hupyridone moiety. The TcAChE residues of symmetry-related molecule are shown in magenta. X-ray structures of TcAChE complexed with these 10- and 12-carbon-tether-linked (S,S)-(-)-4a and (S,S)-(-)-4b show one moiety bound at the , the linker spanning the gorge, and the other moiety bound at the . There are two connecting the hupyridone O to Lys11 Nζ and hupyridone N to Gln185 Oε1 of a symmetry-related molecule of the (R)-3/TcAChE complex. Water molecules are shown as red spheres. Another hydrogen bond connects the hupyridone O to a water molecule, which is bound to Ser286 N. Similarly, the hupyridone at the PAS site of both (-)-4a and (-)-4b forms direct and water-mediated hydrogen bonds with the protein backbone.
About this Structure
1H23 is a Single protein structure of sequence from Torpedo californica. Full crystallographic information is available from OCA.
Additional Resources
For additional information, see: Alzheimer's Disease
Reference
Acetylcholinesterase complexed with bivalent ligands related to huperzine a: experimental evidence for species-dependent protein-ligand complementarity., Wong DM, Greenblatt HM, Dvir H, Carlier PR, Han YF, Pang YP, Silman I, Sussman JL, J Am Chem Soc. 2003 Jan 15;125(2):363-73. PMID:12517147
Page seeded by OCA on Tue Jul 1 06:29:25 2008
Proteopedia Page Contributors and Editors (what is this?)
Categories: Acetylcholinesterase | Single protein | Torpedo californica | Carlier, P R. | Greenblatt, H M. | Han, Y F. | Pang, Y P. | Silman, I. | Sussman, J L. | Wong, D M. | Alzheimer's disease | Bivalent ligand | Dual-site binding | Glycoprotein | Gpi-anchor neurotransmitter degradation | Huperzine some | Hydrolase | Inhibitor | Membrane | Muscle | Nerve | Neurotransmitter cleavage | Serine esterase synapse | Serine hydrolase | Signal
