EFFICIENCY OF TARGETED GENE DELIVERY OF LIGAND-POLY-L-LYSINE HYBRIDS WITH DIFFERENT CROSS-LINKS

Hybrids of a ligand protein crosslinked to a DNA binding protein have been developed as gene delivery vehicles mediated by receptors. To ide ntify the effect of the crosslinks between the ligand and DNA binding protein on gene expression caused by an internalized hybrid-DNA comple x, we prepared two kinds of transferrin-poly-L-lysine (TF-PL) hybrids: one was crosslinked by probably cleavable disulfide bonds (TF-ss-PL) and the other was linked by a probably uncleavable Schiff's base (TF-S chiff-PL). The binding affinity of the hybrids to HeLa cells was not d ifferent. However, the expression of a reporter gene (for luciferase) bound to these hybrids in HeLa cells transfected with TF-Schiff-PL was greater than that of TF-ss-PL.