A new type of hairpin polyamide-CPI conjugate possessing a vinyl linker has been synthesized. Sequence-selective alkylation of double-stranded DNA by conjugates was investigated by high resolution denaturing gel electrophoresis using 450 bp DNA fragments. Highly-efficient DNA alkylation predominantly occurs at the purines of 5'-(A/T)G(T/A)CPu-3' site at nanomolar concentration.