Molecular modeling methods have been applied to characterization of the interaction between a chiral metal complex [Co(phen)2tpphz]^3+ { where phen=1,10- phenanthroline, tpphz=tetrapyrido [3,2-a:2', 3'-c:3", 2"-h:2"', 3"'-j] phenazine} and an oligonucleotide ( B- DNA fragment). The nature of two types of binding, a subject currently in controversy, was explored. Barton et al. proposed that there was enantioselective DNA binding by the octahedral complexes and intercalative access by these complexes from the major groove. Norden et al. suggested that both enantiomers bound extremely strongly to DNA from the minor groove without and noticeable enantioselectivity. Our results support and extend structural models of the minor groove based upon Norden's studies and Barton's enantioselectivity model.

Key words: INTERACTIONS, METAL COMPLEX, SECONDARY STRUCTURE, COBALT COMPLEX, PROBES