Quenching spin diffusion in selective measurements of transient overhauser effects in nuclear magnetic resonance. Applications to oligonucleotides

In high-resoln. NMR, the transfer of longitudinal magnetization from one spin to another (A -> X) under the effect of cross relaxation NOE is often complicated by spin-diffusion pathways through other spins K in the vicinity (e.g., A -> K -> X). It is shown how these undesirable pathways can be quenched by manipulating the magnetization of the two sites A and X with doubly selective inversion pulses. The methods are illustrated by applications to Overhauser effects in the palindromic DNA d(CGCGAATTCGCG)2, which forms a B-type double helix. [on SciFinder (R)]