2003 年 63 巻 2 号 p. 71-78
This study examined the transfection activity and cytotoxicity of the synthetic polycationic peptides, poly (L-lysine), poly (L-ornithine), poly (L-arginine), poly (L-lysine, L-alanine), and poly (L-ornithine, L-leucine), on focusing the effect of molecular weight and concentration of the polypeptide on DNA transfection. The transfection activity was examined in terms of the functional transfer of pSV2cat plasmid DNA into HeLaS3 cells. Cell viability was evaluated by measuring the activity of the lactate dehydrogenase (LDH) released from cells. Poly (L-ornithine), poly (L-arginine) and poly (L-ornithine, L-leucine) induced very high expression levels of a foreign gene in HeLaS3 cells. However, poly (L-lysine) and poly (L-lysine, L-alanine) were not effective. Cytotoxicity was observed at high concentrations of polypeptides and increased in the order of poly (L-ornithine) > poly (L-lysine) > poly (L-arginine) ≥ poly (L-ornithine, L-leucine) > poly (L-lysine, L-alanine). The molecular weight of polypeptide also greatly influenced transfection activity. The higher molecular weight of poly (L-ornithine) (MW 203,400) mediated gene transfer most effectively, and its transfection activity were approximately 5-fold higher than that of poly (L-ornithine), with a molecular weight of 53, 600, whereas the poly (L-ornithine) of a lower molecular weight (MW 11,700) exhibited little activity. The optimal concentrations of the polypeptides depended on the DNA level in an applied solution. The optimal mass ratio of DNA/polypeptide for transfection was 0.4-0.8. The transfection activity of a polypeptide depends on its amino acid composition, molecular weight, and DNA/peptide ratio. High molecular poly (L-ornithine) and poly (L-arginine) were more efficient mediators of DNA transfection than Lipofectin, a commercially available reagent.
