Evaluation of structure and hydrolysis activity of Candida rugosa Lip7 in presence of sub-/super-critical CO2

This work aimed to assess the effect of sub-/super-critical CO2 on the structure and activity of Candida rugosa Lip7 (CRL7) in its solution form. The structure was examined by SDS-PAGE gel electrophoresis, circular dichroism (CD) and fluorescence spectra photometry. Results revealed that the primary structure remained intact after sub-/super-critical CO2 treatment, and the secondary structure altered at the pressure of 10 MPa and temperature 40 °C for 30 min incubation, but it was reflex to its native form with increasing incubation time up to 150 min under 10 MPa and 40 °C. Meanwhile, the tertiary structure via fluorescence spectra analysis showed that the intensity of the maximal emission wavelength at 338 nm decreased under the conditions of 10 MPa and 40 °C for 150 min. Furthermore, the residue hydrolysis activity and kinetics constants (Vmax and Km) of CRL7 treated with sub-/super-critical CO2 were also investigated. In cases of 6 MPa and 35 °C, or 10 MPa and 40 °C for 30 min, activity variance of CRL7 was maybe caused by its secondary structure alteration. But in case of 10 MPa and 40 °C for 150 min, the tertiary structure change was perhaps responsibility for CRL7 activity enhancement.