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 degrees 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 degrees 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 degrees C for 150 min. Furthermore, the residue hydrolysis activity and kinetics constants (V-max and K-m) of CRL7 treated with sub-/super-critical CO2 were also investigated. In cases of 6 MPa and 35 degrees C, or 10 MPa and 40 degrees C for 30 min, activity variance of CRL7 was maybe caused by its secondary structure alteration. But in case of 10 MPa and 40 degrees C for 150 min, the tertiary structure change was perhaps responsibility for CRL7 activity enhancement. (C) 2012 Elsevier Inc. All rights reserved.