Enhancement of transfection efficiency by protamine in DDAB lipid vesicle-mediated gene transfer

Jun You, Masamichi Kamihira, Shinji Iijima

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


We have previously developed a simple gene transfection procedure mediated by cationic lipid vesicles for animal cells, in which a commercially available cationic surfactant, dimethyldioctadecyl ammonium bromide (DDAB), was used for making lipid vesicles. In the present study, we examined enhancement of transfection efficiency for this method by adding protamine to plasmid DNA solution before the formation of DNA/lipid vesicle complexes. Both free-base protamine and protamine sulfate provided enhanced transfection efficiency and expression level, but the optimal amount of the two protamines was different. The enhancement in transfection efficiency and expression level by protamines was observed in all the cell lines (COS-7, Hela, NIH3T3, MDCK, and BHK-21C13) and all the plasmids (pCMVβ, pmiwZ, and pCH110) tested. The enhancement in both transfection efficiency and expression level was at most 20-fold compared with that using only DDAB lipid vesicles. Protamines seemed to protect DNA from degradation by DNase and promote DNA delivery into a nucleus.

Original languageEnglish
Pages (from-to)1160-1167
Number of pages8
JournalJournal of biochemistry
Issue number6
Publication statusPublished - 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology


Dive into the research topics of 'Enhancement of transfection efficiency by protamine in DDAB lipid vesicle-mediated gene transfer'. Together they form a unique fingerprint.

Cite this