STEREOSELECTIVITY IN THE INTERACTION BETWEEN AN OLIGODEOXYNUCLEOTIDE AND DIPEPTIDES IN THE PRESENCE OF THE COPPER(II) ION

A self-complementary decadeoxynucleotide (5'd (CTGGATCCAG)(2)) was syn thesized for the purposes of this study. The systems formed by this de cadeoxynucleotide and the dipeptides of the diastereoisomeric pairs Al a-Ala, Ala-Trp and Leu-Phe both with and without copper(II) were inves tigated by CD spectroscopy. The ternary systems were also submitted to an e.s.r. investigation. The formation of ternary copper(II) complexe s was ascertained. In these complexes, the influence exerted on the B- DNA type conformation of the double strand as observed by CD spectrosc opy strongly suggests intramolecular ligand-ligand interactions which have not been previously described for this type of systems, The discu ssion centers on how the type and disposition of the dipeptide sidecha ins influences the type of interaction in the different complexes, as inferred by the experimental results obtained. (C) 1998 Elsevier Scien ce Inc. All rights reserved.