DNA CONDENSATION FOR GENE-THERAPY AS MONITORED BY ATOMIC-FORCE MICROSCOPY

The atomic force microscope (AFM) was used to assay the extent of DNA condensation in similar to 100 different complexes of DNA with polylys ine (PL) or PL covalently attached to the glycoproteins asialoorosomuc oid (AsOR) or orosomucoid (OR). The best condensation of DMA was obtai ned with 10 kDa PL covalently attached to AsOR, at a lysine:nucleotide (Lys:nt) ratio of 5:1 or higher. These conditions produce large numbe rs of toroids and short rods with contour lengths of 300-400 nm. Some DNA condensation into shortened thickened structures was seen with 10 kDa PL attached to AsOR at Lys:nt ratios of 1.6:1 and 3:1. Some DNA co ndensation was also seen with 4 kDa PL at Lys:nt ratios of 3:1 and hig her. Little DNA condensation was seen with PL alone or with PL convale ntly attached to OR at Lys:nt ratios up to 6:1. AsOR-PL enhanced gene expression in the mouse liver similar to 10- to 50-fold as compared wi th PL alone.