Interaction of synthetic analogs of distamycin with poly(dA-dT): role of the conjugated N-methylpyrrole system
- 1 October 1987
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 26 (20) , 6381-6386
- https://doi.org/10.1021/bi00394a011
Abstract
Two synthetic analogues of distamycin (Dst), PPA and PAP, containing a saturated .beta.-alanine moiety substituting for an N-methylpyrrole chromophore were studied for their interactions with the double-stranded alternating copolymer poly(dA-dT).cntdot.poly(dA-dT) [abbreviated as poly(dA-dT)], with UV absorption and circular dichroism (CD) spectroscopy. The distinctive feature of these analogues is the difference in the extents of extended conjugation due to contiguous pyrrole rings: it decreases in the order Dst > PPA > PAP. Both these analogues bind to poly(dA-dT) in a way similar to Dst, as suggested from the observed red shift in the UV spectra of the ligands upon complexation and the appearance of induced Cotton effects (in the 290-350-nm region) in the CD spectra of the complexes. A comparative study of (i) the spectral features of the complexes between these ligands, Dst and netrospin (Nt) and poly(dA-dT), and (ii) the binding parameters for the association with the polynucleotide suggests that the number and relative positions of the pyrrole moieties influence the spectral features and thermodynamic stabilities of the complexes, and the latter show a progressive decrease in the order Dst > Nt > PPA > PAP. Implications of these results vis-a-vis the molecular basis of Dst-DNA interaction are discussed.This publication has 9 references indexed in Scilit:
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