A comparative study of two lipases from different strains of Staphylococcus aureus

In order to compare lipases from two different Staphylococcus aureus strains (FN 37 and TEN 5), the enzymes from the respective strains were purified using octyl-Sepharose chromatography and characterized with regard to chemical, immunological and enzymatic properties. Differences in the size of the lipases in their native forms necessitated modifications of the purification process, but after purification identical subunits of about 43 kD were found in SDS-PAGE, and both lipases had an apparent molecular weight of 110 kD when subjected to gel chromatography on Sephadex G-200. Analysis of the amino acid compositions of the lipases showed considerable differences. Serine was the predominant amino acid in the FN 37 lipase, whereas glycine was most abundant in the TEN 5 lipase. Nevertheless, the two lipases were similar when tested with double immune diffusion against an antiserum raised against the TEN 5 lipase, and inactivation of enzyme activities by the antiserum followed the same patterns. Enzymatically, the enzymes were similar with regard to salt inhibition, ion dependency and heat inactivation. The substrate specificities, tested against glyceride substrates, were similar. Thus, the two staphylococcal lipases seem to be similar but not identical.