Effect of compressed fluids on the enzymatic activity and structure of lysozyme

Abstract

This study aimed at investigating the effect of pressure, ionic strength and depressurizing rate on the activity and structural conformation of lysozyme using pressurized CO2 (scCO2), liquified petroleum gas (LPG) and R134a as solvents. For this purpose, the experiments were carried out using a variable volume reactor under a 2h of exposure time, at a temperature of 40°C, varying pressure (100–200bar), depressurizing rate (10–50barmin−1) and concentration of sodium chloride (0–50mmolL−1). The highest residual activity observed for high-pressure treatment was 141.0±1.80% for the condition of 150bar and depressurizing rate of 30barmin−1. Analysis of conformational changes of the control and treated enzyme demonstrated that the primary structure of the enzyme remained unchanged and the level of secondary and tertiary structure measured by CD spectra and fluorescence showed potential conformational changes of lysozyme for all the conditions tested.