Facile purification of highly active recombinant Staphylococcus hyicus lipase fragment and characterization of a putative lid region

A fragment of Staphylococcus hyicus lipase gene (Ala248 to Ala640) was inserted into plasmid pET20(b+). The resulting His-tagged recombinant protein (49 kDa) was overexpressed in Escherichia coli BL21(DE3) as an highly active lipase and was purified by nickel-coupled resin. Site-directed mutagenesis showed that in comparison with wild type enzyme, the L326F and L326A enzymes showed a 3.4 and 5 fold increase in the Km, respectively, but only a 44% and a 64% decrease in the kcat/Km, respectively,suggesting thar Leu326 of the putative lid participated in substrate-binding. (C) 1996 Academic Press, Inc.