Koch Lab:Protocols/Dig-bio PCR

Principle

A very easy way to make a batch of uniform DNA molecules labeled at one end with digoxigenin (dig) and the other end with biotin is to perform a PCR reaction using primers that have covalently attached dig or biotin. To visualize how this works, look at this image from Wikimedia Commons User:Madprime. At the bottom of the image, the PCR products which are accumulating show the primer oligonucleotides in red. At the end of many rounds of amplification, almost all fragments will have these primers, and if they are purchased with covalently attached biotin or dig (or other labels, such as fluorescein) then each identical fragment will have the desired labels at each end. (Note that the labels will actually be on opposite strands, which in some cases is important--the simple PCR method does not allow for labeling of the same strand at opposite ends.)