First, restriction sites of SacI and NdeI or BamHI were introduced into Aa LeuRS-CP1Δ20 between residues 241 and 262 by the KOD-plus mutagenesis kit.
The genes encoding Gl LeuRS-59aa and Schistosoma japonicum GST (glutathione transferase) were amplified by PCR from Gl LeuRS-CP1 plasmid and pGEX-4T-1 vector (GE Healthcare) respectively.