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Structural And Functional Analysis Of Acetylcholinesterase Complexes With “In Situ Click‐Chemistry” Inhibitors
Author(s) -
MARCHOT Pascale,
SHARPLESS K. Barry,
TAYLOR Palmer,
BOURNE Yves
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.833.10
Subject(s) - chemistry , active site , cycloaddition , click chemistry , stereochemistry , acetylcholinesterase , ligand (biochemistry) , alkyne , triazole , azide , binding site , enzyme , combinatorial chemistry , biochemistry , organic chemistry , receptor , catalysis
Ligand binding sites on acetylcholinesterase (AChE) comprise the active center, buried at the base of a deep and narrow gorge lined by aromatic residues, and the peripheral anionic site, located at the gorge entry. These features propelled AChE as an initial reaction vessel suited for in situ click‐chemistry synthesis of high‐affinity syn ‐TZ2PA6 and TZ2PA5 inhibitors, forming a central syn ‐triazole upon cycloaddition within the gorge from alkyne and azide reactants bound to the active site and peripheral site, respectively [1,2]. Subsequent crystallographic analyses of mouse AChE or its Tyr337Ala mutant in complexes with the syn‐ and anti ‐TZ2PA6 regioisomers demonstrated that association of the syn product is accompanied by distinctive side chain positions, freezing‐in‐frame a conformation distinct from an unbound state or an anti complex [3,4]. To correlate the inhibitor dimensions with reactivity and explore whether cycloaddition can occur in a crystalline template, we developed crystal‐soaking procedures and solved structures of AChE complexes with the two TZ2PA5 regioisomers and their TZ2 and PA5 precursors [5]. These new structures, complementary to those of the preformed TZ2PP6 complexes, point to yet undescribed motions in the active site and at the gorge mouth associated with TZ2 binding and reveal coordinated side chain motions that guide the enzyme toward a state favoring syn ‐triazole formation. We will present the rationale of the work, describe those molecular determinants that dictate, in a rate‐limiting step, proper alignment of the azide and alkyne reactants to form the triazole product within the gorge, and compare our data with those from other in situ click chemistry studies. Support or Funding Information Supported by grants RO‐1‐GM18360‐41 and UO1‐NS 058046 (to PT) and by CNRS grants “Action CNRS/USA” and “PICS” (to PM and YB)