An NMR self-diffusion study of the interactions between spermidine and oligonucleotides

Self‐diffusion coefficients have been determined by pulsed field gradient nmr methods for spermidine in solutions of the oligonucleotides d(GC)4 and d(GGAATTCC). The self‐diffusion behavior of spermidine in solution of d(GC)4 is very similar to that observed previously for methylspermidine (completely N‐methylated spermidine). Moreover, the self‐diffusion behaviors of spermidine in solutions of d(GC)4 and d(GGAATTCC) are also quite similar, indicating that there is no significant influenceon on self‐diffusion of oligonucleotide base composition. Furthermore, self‐diffusion coefficients of the oligonucleotide d(GC)8 show only a small dependence on oligonucleotide concentration, and no measurable dependence on sodium ion or magnesium ion concentration. © 1996 John Wiley & Sons, Inc.