In addition to the current PEG thread, it does seem to be important to remove all PEG from ssDNA template prepared for sequencing. I can only vouch for this from using Klenow for seq so I'm not sure about T7/Sequenase or cycle methods. Jim Brannigan Chemistry Dept University of York York YO1 5DD UK jab5 at uk.ac.york.vax jab at uk.ac.york.yorvic