comparable studies on the stability of proteases from Pseudomonas aeruginosa against thermolysin from Bacillus thermoproteolyticus in the presence of organic solvents

Extensive research has been conducted on the stability of proteases in organic solvents, because they have numerous applications in organic media. Thermolysin from Bacillus thermoproteolyticus is a highly thermostable Zn-metalloprotease and is applied in industry for peptide synthesis, a reaction essentially performs in organic media. However, thermolysin has low stability at organic solvents.In contrast, its homologous enzyme, Pseudomonas aeruginosa elastase (PAE) is an organic solvent stable protease. In the present study, recombinant PAE was purified and compared with thermolysin in different organic solvents. For this purpose, activity of enzymes was measured in ethanol, methanol, isopropanol, dimethylformamide, glycerol and ethylenglycol (0-50 % (V/V)). Except isopropanol and ethanol, not only the elastase activity was not decreased, but also strongly increased in organic solvents. However, activity of thermolysin was abolished in all organic solvents. In the presence of DTT 1mM, the PAE activity was notably decreased in organic solvents. Considering that PAE contains two disulfide bonds at N- and C-terminal domains, it may suggest that disulfide bonds play a role in organic solvent stability of PAE.