DNA-binding characteristics of a synthetic analogue of distamycin

The interaction between a synthetic analogue (structure shown in fig. 1) of distamycin, and DNA has been studied with a view to understanding the conformational and chemical basis of the sequence specific binding of distamycin with DNA. The complex formation between the trimer and DNA is apparent from the red shift in the UV spectrum and appearance of the induced CD band in 300nm-350nm region. The relevant data suggest: (i) the binding is A-T base specific though the specificity is not as pronounced as in distamycin (1,2) and (ii) it occurs via the minor groove of DNA. The partial loss in A-T base specificity may be due to the replacement of N-methyl pyrrole by benzene or the increase in curvature of the backbone of the ligand as a result of this replacement.