Hi,
I learn that using Vaccina virus Topoisomerase I can create sticky ends for A-overhang PCR product. But there are some commercial kits available for blunt end PCR product, like Invitrogen ZeroBlunt kit. According to the map, it looks like they use the same Vaccina virus Topoisomerase enzyme (because the vector ends with (C/T)CCTT), But I like to know why the resulting vector is blunt end, unlike traditional TOPO-vector which contains a T-overhang?
Thank you