Gas-phase hydrogen/deuterium exchange of positively charged mononucleotides by use of Fourier-transform ion cyclotron resonance mass spectrometry.
The gas-phase structures of protonated (deoxy)nucleoside-5'- and 3'-monophosphates (mononucleotides) have been examined by the use of gas-phase hydrogen/deuterium (H/D) exchange and high-field Fourier-transform ion cyclotron resonance mass spectrometry. These nucleotides were reacted with three different deuterating reagents: ND3, D2O, and D2S, of which ND3 was the most effective. All mononucleotides fully exchanged their labile hydrogen for deuterium with ND3 with the exception of deoxycytidine-3'-monophosphate, deoxyadenosine-5'-monophosphate, adenosine-5'-monophosphate, and adenosine-3'-monophosphate. Semiempirical calculations demonstrate the presence of hydrogen bonding upon protonation of the purine mononucleotides which may lead to incomplete H/D exchange. H/D exchange rates differed between the deoxymononucleotides and the ribomononucleotides, suggesting that the 2'-OH group plays an important role in the exchange process. Reactions of nucleosides and mononucleotides with D2O demonstrate that a structure-specific long-lived ion-molecule complex between D2O and the mononucleotide involving the phosphate group is necessary for exchange to overcome the high-energy activation barrier. In contrast, a structure-specific long-lived ion-molecule complex between the mononucleotides and ND3 is not required for exchange to occur.
Department of Chemistry, Louisiana State University, Baton Rouge 70803, USA.
K B
KB
Green-Church
P A
PA
Limbach
M A
MA
Freitas
A G
AG
Marshall
D017357:Cyclotrons; D003903:Deuterium / Q000737:chemistry; D005583:Fourier Analysis; D006859:Hydrogen / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics
D009711:Nucleotides; D011743:Pyrimidines; D006859:Hydrogen; D003903:Deuterium