Abstract: According to the amino acid sequence and codon preference of E. coli, the human growth hormone(hGH) gene was optimized to avoid rare codons. The total length of the synthesized gene was 1040 bp because a promoter and a signal peptide sequence were added into it. Thirty oligonucleotides were designed and synthesized. The whole DNA sequence was synthesized by the improved two-step method. The sequencing result show that two complete correct gene were synthesised. The error rate of synthesized gene treated by T7 endonuclease I reduced 93.93% in comparison with the standard two-step synthesis method.

Key words: Human growth hormone, Gene synthesis, Two-step method