title: Effect of sub- and supercritical CO2 treatment on the properties of Pseudomonas cepacia lipase.
abstract: In this work, we have investigated the influences of sub- and supercritical CO2 treatment on the properties of Pseudomonas cepacia lipase (PCL), including its esterification and transesterification activities, structural changes and stability. Results demonstrated that exposure time to subcritical CO2 treatment had a negative effect on PCL transesterification activity whereas exposure time to supercritical CO2 treatment had a positive effect. But generally, most compressed treatments significantly enhanced PCL esterification activity. Conformational analysis by FT-IR and fluorescence emission spectra revealed that enhanced activities after supercritical CO2 treatment were correlated with the secondary and tertiary structural changes of PCL. Secondary structure changes also appeared to be responsible for enhancement of PCL activities by subcritical CO2 treatment. Compared to native PCL, treated PCL's esterification activity significantly decreased in hydrophilic organic media, while transesterification activity significantly increased in tert-amyl alcohol and acetone. After supercritical treatment, the thermal stability of PCL significantly decreased in esterification reactions, however, there was no significant difference in transesterification reactions.
authors.affiliation: Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Chen
authors.forename: Houjin
authors.initials: H
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Yunjun
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000096:Acetone / Q000494:pharmacology; D016956:Burkholderia cepacia / Q000187:drug effects / Q000201:enzymology*; D002245:Carbon Dioxide / Q000494:pharmacology*; D004795:Enzyme Stability; D004951:Esterification / Q000187:drug effects; D006358:Hot Temperature; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism*; D000439:Pentanols / Q000494:pharmacology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012997:Solvents / Q000737:chemistry / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000439:Pentanols; D012997:Solvents; D000096:Acetone; D002245:Carbon Dioxide; C032765:tert-amyl alcohol; D008049:Lipase