Sequence-specific recognition of B-DNA by oligo(N-methylpyrrolecarboxamide)s.

Abstract
Four homologous oligopeptide-EDTA molecules, tri-, tetra, penta and hexa(N-methylpyrrolecarboxamide)-EDTA, in the presence of Fe(II), O2 and dithiothreitol, cleave 32P-end-labeled restriction fragments from plasmid pBR322 DNA at common locations rich in A .cntdot. T base pairs that differ in the size of the binding site. From analysis of the cleavage patterns visualized by high-resolution denaturing gel electrophoresis, the oligopeptides with 3, 4, 5 and 6 N-methylpyrrolecarboxamide units, containing 4, 5, 6 and 7 amide NH bind sites of A .cntdot. T-rich DNA consisting of 5, 6, 7 and 8 contiguous base pairs, respectively. The general rule of n amides affording binding site sizes of n + 1 base pairs is consistent with the oligopeptides binding in the minor groove of right-handed DNA, with the amide NH groups forming bridges between the adjacent N-3 and O-2 atoms of adenine or thymine on opposite strands of the DNA helix.

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