title: Identification of a lacosamide binding protein using an affinity bait and chemical reporter strategy: 14-3-3 ζ.
abstract: We have advanced a useful strategy to elucidate binding partners of ligands (drugs) with modest binding affinity. Key to this strategy is attaching to the ligand an affinity bait (AB) and a chemical reporter (CR) group, where the AB irreversibly attaches the ligand to the receptor upon binding and the CR group is employed for receptor detection and isolation. We have tested this AB&CR strategy using lacosamide ((R)-1), a low-molecular-weight antiepileptic drug. We demonstrate that using a (R)-lacosamide AB&CR agent ((R)-2) 14-3-3 ζ in rodent brain soluble lysates is preferentially adducted, adduction is stereospecific with respect to the AB&CR agent, and adduction depends upon the presence of endogenous levels of the small molecule metabolite xanthine. Substitution of lacosamide AB agent ((R)-5) for (R)-2 led to the identification of the 14-3-3 ζ adduction site (K120) by mass spectrometry. Competition experiments using increasing amounts of (R)-1 in the presence of (R)-2 demonstrated that (R)-1 binds at or near the (R)-2 modification site on 14-3-3 ζ. Structure-activity studies of xanthine derivatives provided information concerning the likely binding interaction between this metabolite and recombinant 14-3-3 ζ. Documentation of the 14-3-3 ζ-xanthine interaction was obtained with isothermal calorimetry using xanthine and the xanthine analogue 1,7-dimethylxanthine.
authors.affiliation: Division of Medicinal Chemistry and Natural Products, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599-7568, USA.
authors.forename: Ki Duk
authors.initials: KD
authors.lastname: Park
authors.forename: Dongwook
authors.initials: D
authors.lastname: Kim
authors.forename: Onrapak
authors.initials: O
authors.lastname: Reamtong
authors.forename: Claire
authors.initials: C
authors.lastname: Eyers
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Gaskell
authors.forename: Rihe
authors.initials: R
authors.lastname: Liu
authors.forename: Harold
authors.initials: H
authors.lastname: Kohn
mesh_terms: D048948:14-3-3 Proteins / Q000032:analysis* / Q000378:metabolism*; D000081:Acetamides / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000927:Anticonvulsants / Q000737:chemistry / Q000494:pharmacology*; D001921:Brain / Q000378:metabolism; D000078334:Lacosamide; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008958:Models, Molecular; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D048948:14-3-3 Proteins; D000081:Acetamides; D000927:Anticonvulsants; D000078334:Lacosamide