MOLECULAR MODELING STUDY OF DNA-TROEGERS BASES INTERACTIONS

The two enantiomeric forms : 1R,5R (R) and 1S,5S (S) of the Troeger's base analog thano-9,10,19,20-tetrahydrodiacridino-[b,f]-[1,5]- diazoci ne which possess a C-2 axis of symmetry, are susceptible to interact d ifferently with DNA This paper reports the results of molecular modell ing calculations on B DNA-Troeger's base complexes. Two interaction mo des have been examined : intercalation and binding in the grooves. Int o the limits of accuracy of such a kind of calculations, some tendenci es seem to appear. In the intercalation mode, the R and S enantiomers exhibit a selectivity for alternating dinucleotidic sequences and the minor groove is enantioselective for S. Binding in the major groove is selective for S with G-C sequences, and in the minor groove the stere oselectivity appears for R with A-T sequences. The S-(dG-dC)(5).(dG-dC )(5) complex in the major groove seems to be the most favoured.