[Study of the spatial structure of the duplex (Phn-NH(CH2)NH)pd(CCAAACA).pd(TGTTTGGC) with covalently bound 10-(2-hydroxyethyl)phenazine by in aqueous solution by 2D-(1)H-NMR and by limited molecular mechanics].

Detailed investigation of the spatial structure of duplex (Phn-NH(CH2)2NH) x pd(CCAAACA).pd(TGTTTGGC) having a covalently linked N-(2-hydroxyethyl)-phenazine in aqueous solution was continued by means of one- and two-dimensional 1H-NMR spectroscopy. Distances between the protons of the oligonucleotides as well as distances between the phenazinium and the nearest nucleotide groups protons were determined from the series of one-dimensional NOE experiments. The effective correlation time tau c determined for some proton pairs shows the phenazinium fragment to have greater internal motion than the heterocyclic bases. The deoxyribose protons coupling constants show the sugars to be in 2'-endo-conformation. The restrained molecular mechanics have yielded a possible structure of duplex in the aqueous solution fitting the experimental set of interproton distances.