DNA Modification - (Feb/25/2007 )

I have been comparing the relative abilities of the 32P-Postlabeling and LC-MS/MS techniques for the detection and quantitation of a number of novel DNA adducts of deoxyguanosine in human DNA. My initial results are expressed as either ‘x pmol/100ug DNA’ or ‘x mmol/mmol dGuo’; however I want to express the results as ‘number of adducts per 106 nucleotides’. Can anyone, please, give me some advice or pointers as to how I go about converting my data into the required format?

Off the top of my head, I'd imagine you'd have to know the length of DNA you're testing. If you have a mixture of different molecules, you might have trouble, simply because you cannot convert from mmol or ug into number of nucleotides.

Can you do your experiments on a PCR product?

Unfortunately, I don't know the length of the DNA used, although the DNA was essentially genomic DNA isolated and extracted from a variety of human cell lines, so you could assume that the length of the isolated DNA is 3.2 x 10^9 base pairs.

The work could of been done on PCR products or synthetic oligonucleotides, but at the time I need to analyze and obtain basal measurements of these adducts under physiological conditions. The use of PCR products and/or oligonucleotides will be used later in structural and functional studies.