[Study of solid-phase catalytic isotopic exchange of hydrogen in alpha-conotoxin G1 under the effect of spillover-tritium].
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.
Zolotarev
Iu A
IuA
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. zolya@img.ras.ru
Bocharov
E V
EV
Dadaian
A K
AK
Kasheverov
I E
IE
Zhmak
M N
MN
Maslennikov
I V
IV
Borisov
Iu A
IuA
Arsen'ev
A S
AS
Miasoedov
N F
NF
Petlin
V I
VI
D000595:Amino Acid Sequence; D002384:Catalysis; D020916:Conotoxins / Q000737:chemistry* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D014316:Tritium / Q000737:chemistry*
D020916:Conotoxins; D014316:Tritium