Determination of 3J(C,P) and 3J(H,P) coupling constants in nucleotide oligomers with FIDS-HSQC

A method for measuring J(C,P) and J(H,P) coupling constants is presented, based on fitting a target multiplet containing the heteronuclear coupling to a reference multiplet that lacks the heteronuclear coupling. In DNA and RNA oligonucleotides, information on backbone torsion angles can be obtained from these couplings. Experimental multiplets are obtained from 31P-coupled and 31P-decoupled 1H, 13C HSQC spectra of Rp-cyclic methylphosphonate. The accuracy to which the heteronuclear coupling constants can be determined depends on the signal-to-noise ratio of the experimental data and is analyzed in detail.