Abstract: The gene encoding a small heat shock protein of the hyperthermophile Pyrococcus furiosus(Pfu-sHSP) was cloned into plasmid pT7473.The Pfu-sHSP that had a high content of rare codons was hardly expressed in Escherichia coli BL21(DE)3,but could be overexpressed in Escherichia coli BL21(DE)3 —Codonplus—RIL,a host containing extra copies of tRNA genes of the rare codon AGA(arg),AGG(arg),AUA(ile) and CUA(leu).Cells overexpressing Pfu-sHSP were disrupted by ultrasonication,and the sediment was re-suspended and wa...