title: [Study of solid-phase catalytic isotopic exchange of hydrogen in alpha-conotoxin G1 under the effect of spillover-tritium].
abstract: Tritium-labeled alpha-conotoxin G1 with a molar radioactivity of 35 Ci/mmol and full biological activity (according to the binding to nicotinic acetylcholine receptor) was obtained by the high-temperature solid-state catalytic isotope exchange (HSCIE). The tritium distribution in the molecule of alpha-conotoxin G1 was revealed by 3H NMR spectroscopy. Tritium was found in all amino acid residues except for the Asn4-Pro5-Ala6 fragment. The data on the comparative reactivity of C-H bonds, the ab initio quantum-chemical calculation of the hydrogen exchange reaction, and the information on the spatial structures of alpha-conotoxin G1 in solution and in crystal state allowed us to establish that the reactivity of H atoms may be increased by their interaction with the electron donor O and N atoms at the transition state of the HSCIE reaction. A decrease in the rate of the HSCIE reaction could be caused by both a poor spatial accessibility of C-H bonds and a limited mobility of the peptide fragment containing these bonds.
authors.affiliation: Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. zolya@img.ras.ru
authors.forename: Iu A
authors.initials: IuA
authors.lastname: Zolotarev
authors.forename: E V
authors.initials: EV
authors.lastname: Bocharov
authors.forename: A K
authors.initials: AK
authors.lastname: Dadaian
authors.forename: I E
authors.initials: IE
authors.lastname: Kasheverov
authors.forename: M N
authors.initials: MN
authors.lastname: Zhmak
authors.forename: I V
authors.initials: IV
authors.lastname: Maslennikov
authors.forename: Iu A
authors.initials: IuA
authors.lastname: Borisov
authors.forename: A S
authors.initials: AS
authors.lastname: Arsen'ev
authors.forename: N F
authors.initials: NF
authors.lastname: Miasoedov
authors.forename: V I
authors.initials: VI
authors.lastname: Petlin
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D020916:Conotoxins / Q000737:chemistry* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D014316:Tritium / Q000737:chemistry*
chemical_list: D020916:Conotoxins; D014316:Tritium