FIGURE 2.

Denaturing DNA polyacrylamide gel image. Denaturing polyacrylamide gel electrophoresis was performed to monitor the ligation steps. Several pieces of oligonucleotides were first annealed to make a 147-bp dsDNA fragment with an additional 10-base single strand at the N terminus (lane 1: before ligation) and then ligated with Taq DNA ligase (lane 2) or T4 DNA ligase (lane 3) to seal the nicks on the DNA construct. Ligated DNA fragments were compared with the 147-bp 601 DNA, which was restricted from a plasmid containing a 601 sequence (see “Experimental Procedures” for detailed preparation) (lane 4). ssDNA, single-stranded DNA.