DUPLEX STABILIZATION BY DNA-HOECHST-33258 CONJUGATES - EFFECTS OF BASE-PAIR MISMATCHES

Three types of DNA-Hoechst conjugates are examined for duplex stabilit y in the presence of single-site base pair mismatches. Two of the comp lexes have the Hoechst Ligand tethered to an internal phosphate residu e, while the third complete; employs terminally labeled conjugate. The presence of the mismatched base pair reduces the T-m values for the n on-conjugate duplexes as is expected. Addition of the conjugated Hoech st ligand enhances the T-m values for the mismatched duplexes, but the se values remain significantly below that obtained for the native conj ugated duplex. While stabilization by the tethered ligand is observed for both cognate and non-cognate sequences, the differences suggest th at significant sequence selectivity is still apparent for these conjug ates.