Hybrid gene synthesis: its application to the assembly of DNA sequences encoding the human parathyroid hormones and analogues.

Bypassing any intermediate steps of purification and gene assembly, several synthetic oligonucleotides constituting a DNA duplex with a small base-mismatching region were phosphorylated, annealed, and ligated directly into a linearized plasmid vector. After transformation in bacteria, the two plasmid strands individually yielded two different plasmids bearing altered versions of the same gene. Via this approach, DNA coding sequences of the human parathyroid hormone and analogues were synthesized and cloned in Escherichia coli.