Gas phase RNA and DNA ions 2. Conformational dependence of the gas-phase H/D exchange of nucleotide-5'-monophosphates.
The conformational dependence of the gas-phase hydrogen/deuterium (H/D) exchange of nucleotide-5-monophosphate anions with the H/D exchange reagent D2S is reported here. The electrospray-generated [M-H]- anions of adenosine-5'-monophosphate, adenosine-5'-carboxylic acid, ribitol-5-phosphate, and 2-deoxy-ribitol-5-phosphate were reacted with D2S in the gas phase. Their reactivity (adenosine-5'-monophosphate exchanged 2 of 5 labile hydrogens, adenosine-5'-carboxylic acid exchanged 1 of 4, ribitol-5-phosphate exchanged 2 of 3, and 2-deoxy-ribitol-5-phosphate exchanged 1 of 2) suggests that the hydroxyl group in the 2 position of the ribose sugar and the amino hydrogen on the nucleobase do not exchange readily with D2S. Semiempirical molecular orbital calculations suggest that the labile hydrogens in these positions are thermodynamically facile to exchange but as a conformation inaccessible to the presumed phosphate anion, consistent with a mechanism in which the phosphate anion complexes with the exchange reagent and assists H/D exchange at a neighboring site.
Freitas
M A
MA
Department of Chemistry, The Ohio State University, Columbus 43210, USA. freitas@chemistry.ohio-state.edu
Marshall
A G
AG
D000241:Adenosine / Q000031:analogs & derivatives / Q000737:chemistry*; D000249:Adenosine Monophosphate / Q000032:analysis; D000242:Cyclic AMP / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*; D012255:Ribitol / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
C102887:adenosine-5'-carboxylic acid; D000249:Adenosine Monophosphate; D012255:Ribitol; D012313:RNA; D004247:DNA; D000242:Cyclic AMP; D000241:Adenosine