Involvement of Gly 311 residue on substrate discrimination, pH and temperature dependency of recombinant Staphylococcus xylosus lipase: A study with emulsified substrate

The purified SXL-G311D and SXL-G311K mutants show distinct pH profiles. The SXL-G311D mutant is optimally active at pH 6.5, whereas, the SXL-G311K mutant is active at pH 9.5. In addition, these two mutants show an important decrease in the specific activities that generates a decrease in the catalytic efficiency (kcat/Kmapp.). We can essentially notice that the SXL-G311K mutant displays a 33- or 44-fold decrease in kcat/Kmapp. values compared to the SXL-WT, when using TC4 or TC8 as substrate, respectively.