of mismatch‐binding molecules with hairpinDNA that contains a d(CGG)3 sequence in the loop is described (see picture). Native polyacrylamide gel electrophoresis of hairpin‐loopDNA shows that the newly synthesized mismatch‐binding molecule, a tetrameric form of N‐methoxycarbonyl‐1,8‐naphthyridine, assists the formation of a loop–loop complex of twoDNAhairpinloops.