Lipofection of 293 cell line with large plasmid DNA; help req.

[O.Khan]

I am attempting to transfect 293 cells with large ~40kb plasmid carrying the 
adenovirus whole genome, using DOTAP. I dont seem to get good efficiency of 
transfection. Also I get a high cell death, (DOTAP-DNA-media mixture is kept for 
overnight on the cells). Can anyne having experience with lipofecting large plasmids 
help me out with this.
Thanks,
Obaid Yusuf Khan