Isolation of the gene encoding staphylokinase and its high-expression in E. coli

After amplifying the SAK coding sequence from the chromosomal DNA of the lysogen of Staphylococcus aureus strain FR610, the isolated fragment was sequenced by dideoxy method, recombined in vitro with plasmid pBV220, and transformed E. coli DH5alpha cells. An high-expression strain was obtained. The expressed SAK amounted to 70% of the total bacterial protein. The specific activity of the SAK was 3×10~(6) units/mg, measured by comparison with a standard preparation. A high-expression E. coli strain for SAK was successfully obtained.