The detn. of the soln. structure of small non-natural oligopeptides and oligonucleotides by NMR, which is one of the main research topics of our group, is illustrated on the example of an 8-mer p-DNA duplex. P-DNA, the 3'-desoxy analog of p-RNA, forms an highly selective pairing system but its pairing strength is less than that of analogous p-RNA sequences. The NMR study reveals that the backbone of p-DNA corresponds more closely to the conformation predicted for pentapyranose nucleic acids by qual. conformational anal. than p-RNA. [on SciFinder (R)]