I've just seen an ad for Invitrogens PCR cloning kit where they
claim that PCR products always have a 3' A added on. Does anyone
know anything about this (reference?). I have always done a klenow step
before cloning but didn't realise that the ends were ragged because extra
bases were added on? Quite a few of my applications would be wrecked by an
extra A so any tips about eliminating them (if they exist) would be great.