PCR question, need help please! - (May/25/2006 )

I PCRed fragment of DNA I want to clone from a vector. The gel showed the molecular weight for my product, but also a band at the top, which I think is the vector. If I want to purify my fragment, do I need to do it purifying it from the gel, or can I purify it directly from the PCR sample? Im using QAgen PCR purification kit. Does anybody knows if this kit discriminates between circular DNA and linear DNA?

Thank you

DId you do negative control (ie - no DNA)? I doubt that the band is due to contamination, but anyways..
How specific are your primers?

I suggest purify from the gel, if your band is not contamination.

Thank you, that's what I did, I purified it from the gel, uhum,, is not contamination, negative control is fine.

Actually the kits discriminate by DNA size. But if you have e.g. 1.5kb insert and 4kb vector, it won't work I guess. So I'd use the gel extraction.

oh, slightly to late...

Yeah,, but thak you anyways,, thats what I wanted to know.