Check the restriction digestion map of all the three plasmids, and select two or more enzymes that are cutting your nonspecific plasmid but don’t have any site in your plasmid of interest. After digestion, you will easily elute your plasmid from the gel. Transform it in E.coli , do fresh mini-prep and send it for sequencing. But chances of getting such an enzyme which is cutting two commercial available plasmids and not the third plasmid is very low.

Best

Check the restriction digestion map of all the three plasmids, and select two or more enzymes that are cutting your nonspecific plasmid but don’t have any site in your plasmid of interest. After digestion, you will easily elute your plasmid from the gel. Transform it in E.coli , do fresh mini-prep and send it for sequencing. But chances of getting such an enzyme which is cutting two commercial available plasmids and not the third plasmid is very low.

Best

Yeah, you can try by restriction digestion.

Hey Arada,

i once had that same problem. Here is my solution:

I suppose your plasmids have different resistance cassettes? In that case you can isolate the plasmids and re-transform them in E.coli. Afterwards distribute the colonies on each of those three different antibiotics. Colonies only growing on your antibiotic of choice, but not on the two other antibiotics, have taken up your desired plasmid. Afterwards you can isolate the plasmid and do whatever you like.

I screened 40 colonies and 3 of them where positive.

Good luck,

David