FAQ: Why are there larger than expected bands after digestion with the BamHI-HF™ restriction enzyme?
The increased specificity for the BamHI-HF™ cut site has increased binding of the enzyme to the DNA and the enzyme may remain attached to the DNA during gel electrophoresis. To disrupt binding, add SDS to a final concentration of 0.5% - 1% or purify DNA before electrophoresis.