Details

Autor(en) / Beteiligte

• Freitas, MA
• Shi, SD-H
• Hendrickson, CL
• Marshall, A G

Titel

Gas-Phase RNA and DNA Ions. 1. H/D Exchange of the [M - H] super(-) Anions of Nucleoside 5'-Monophosphates (GMP, dGMP, AMP, dAMP, CMP, dCMP, UMP, dTMP), Ribose 5-Monophosphate, and 2-Deoxyribose 5-Monophosphate with D sub(2)O and D sub(2)S

Ist Teil von

• Journal of the American Chemical Society, 1998-10, Vol.120 (39), p.10187-10193

Erscheinungsjahr

1998

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• H/D exchange from D sub(2)O and D sub(2)S to electrosprayed [M - H] super(-) nucleoside 5'-monophosphate anions (GMP, dGMP, AMP, dAMP, CMP, dCMP, UMP, TMP) is examined by Fourier transform ion cyclotron resonance mass spectrometry at 9.4 T, along with sugar phosphate controls (ribose 5-monophosphate (R5P) and 2-deoxyribose 5-monophosphate (dR5P)). The relative exchange rates of the nucleotides with D sub(2)O were dR5P > dCMP > R5P > CMP > dAMP > UMP > AMP > dTMP >> dGMP >> GMP, and with D sub(2)S were CMP > UMP approximately dTMP > dCMP > dAMP > AMP > R5P > dR5P >> dGMP >> GMP. All exchange rates increase dramatically on changing from D sub(2)O to D sub(2)S, due to the smaller gas-phase acidity difference between exchange reagent and the nucleotide: Delta ( Delta H sub(acid)) > 60 kcal mol super(-1) for D sub(2)O vs Delta ( Delta H sub(acid)) > 20 kcal mol super(-1) for D sub(2)S. Ab initio calculations on model compounds at the MP2/6-31+G*//HF/6-31+G* level yield the following order of calculated acidities for each of the exchangeable hydrogens: R sub(2)O sub(3)PO-H > R sub(2)N-H > (R sub(2)O-H on ribose) > RN-H sub(2) > (R sub(2)O-H on 2-deoxyribose). The present results provide a quantitative measure of proton exchange rates, in minutes for D sub(2)S (rather than hours for D sub(2)O) for gas-phase nucleotide anions, thereby opening up a wide range of extensions to chemically modified nucleotides as well as single-stranded and duplex RNAs and DNAs.