LAUSR

The parameters half‐life, z value, enthalpy, entropy, and free energy were evaluated in the temperature range of 40 to 55°C for a Bacillus sp. P45 protease present in a medium composed of ionic liquid (IL) and organic solvent. The protease was previously treated in IL [Emim][Tf2N] and increased activity was observed in four out of five organic solvents tested. The reaction medium containing acetone and IL (1:1 v/v ratio) was more stable than the buffer medium, with half‐life of 2.4 h at 55°C. Thermodynamic parameters values showed there was probably less rupture of non‐covalent bonds that stabilize the protein structure, which promoted the protease P45 stabilization. According to this study it was concluded that the protease P45 in a medium composed of [Emim][Tf2N] and acetone may be used at higher temperatures than those employed in buffer or medium containing organic solvent. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1102–1108, 2018