Investigation of enzymatic activity, stability and structure changes of pectinase treated in supercritical carbon dioxide

摘要

The activity and stability of enzymes in supercritical carbon dioxide fluid are the crucial points and basis for developing and applying green, environmentally friendly processes and/or reactions in this water free media in different industries, which has attracted increasing interesting recently. The objective of the present work is to investigate the activity and stability of pectinase in supercritical carbon dioxide media, as well as for its structure and conformation changes. The results show that the activity and stability of pectinase were significantly improved under appropriate conditions. Significant increases in activity and stability of treated pectinase could be available with pressure lower than 15.0 MPa, whereas, temperature tends to reduce enzymatic activity and stability. An excellent stability of pectinase with improved activity was observed with duration from 0.5 h to 4.0 h. Fourier transfer infrared spectra, ultraviolet spectra, fluorescence spectra and scanning electron microscopy analyses indicate that alterations in the secondary and tertiary structures, and morphology of treated pectinase, were occurred without conspicuous changes in its primary structure. An exposure of the residual side aromatic groups of tryptophan on polypeptide to outer surface of the enzyme in solution was also detected. Therefore, all the investigations further demonstrate that the supercritical treatment is an efficient method to improve the activity and stability of the enzyme due to conformational changes, and there is also a feasible to perform cleaner and sustainable production processes or reactions with pectinase in supercritical carbon dioxide media. (C) 2016 Elsevier Ltd. All rights reserved.