Release of DNA binary complexes from the ternary complexes by carboxymethyl poly(L-histidine).

The DNA ternary complexes with carboxymethyl poly(L-histidine) (CM-PLH) and poly(ethylenimine) (PEI) have released the DNA binary complexes with PEI by the protonation of CM-PLH at endosomal/lysosomal pH. The dissociation of the CM-PLH from the CM-PLH/PEI/DNA ternary complexes is proved by the fluorescence resonance energy transfer (FRET) analysis between the CM-PLH and PEI. The resulting PEI/DNA binary complexes easily released DNA, as compared with the CM-PLH/PEI/DNA ternary complexes, which was examined by competitive exchange with dextran sulfate. The release of the DNA binary complexes from the ternary complexes is promising mechanism for higher transfection activity by the CM-PLH/PEI/DNA ternary complexes.