PCR product on gel as smear - DNA isolated from paraffin blocks why smear? (May/12/2005 )

Hi,

I have been isolating DNA from paraffin embeded tissue using quiagen mini kit. I lysed few tissue sections in a standard buffer with proteinase K(0.4mg/ml) and keep it overnight . then i continue with quiagen kit protocol. My problem is out of the samples i have isolated after PCR for Viral DNA very few gives distint good bands while the rest are with dense smear. n out of these few good ones they stop amplifying after storing at 4deg C for one week . repeated freezing and thawing degrades DNA . I elute my DNA with AE buffer supplied with the KIT. Should i try with water . Pl help me resolve this two problem(smear as well as DNA storage).

thanks
remi

Hi Remi,

How big is your PCR product. remember that DNA from paraffin section is usually degraded and is hard to yield big product such as >500 bp.