The sodium ions inside a lipophilic G-quadruplex channel as probed by solid-state (23)Na NMR.
We report solid-state 23Na NMR and X-ray crystallographic results for a self-assembled G-quadruplex channel formed by a guanine nucleoside, 5'-tert-butyl-dimethylsilyl-2',3'-O-isopropylidene guanosine (G 1). The study provides an unambiguous 23Na NMR identification for the Na+ ions inside a lipophilic G-quadruplex channel. The crystalline nature of the sample yields a remarkably high resolution in the 23Na multiple-quantum magic-angle spinning (MQMAS) spectrum, making it possible to extract very accurate 23Na NMR parameters for each of the three crystallographically distinct Na sites. The observation of a single Na+ ion from a 9-kDa system demonstrates the potential of solid-state 23Na NMR as a complementary technique to X-ray for detecting Na+ ions in biological structures.
Wong
Alan
A
Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Fettinger
James C
JC
Forman
Scott L
SL
Davis
Jeffery T
JT
Wu
Gang
G
D006147:Guanine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009690:Nucleic Acid Conformation; D011684:Purine Nucleosides / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*
D011684:Purine Nucleosides; D006147:Guanine; D012964:Sodium