B–Z transition of (dA-T)n duplexes induced by a spermine porphyrin-conjugate via an intermediate DNA conformation

Abstract

The spermine conjugate of the cationic porphyrin ligand (1) selectively induced the B–Z transition of the [(dA-T)_n]₂ sequence at low salt concentrations. The [(dG-C)_n]₂ sequence was not transformed into the Z-form. The B–Z transition was induced via an intermediate DNA conformation, which was formed by the external binding and formation of an assembly of 1 onto B-DNA.