Effects of High Pressure Processing on the Activity and the Conformation of Horseradish Peroxidase

High pressure treatment on the activity of peroxidase in fruits and vegetables can affect the sensory quality and shelf life of fruit and vegetable products, and thus it is necessary to study the relationship between the changes of peroxidase activity and its structure under the conditions of high pressure. Circular dichroism (CD) and fluorescence spectrometry (FP) were used to study the effect of high pressure treatment at 100, 300, 500 MPa for 15 min at room temperature on the secondary and tertiary structure of horseradish peroxidase (HRP) and its activity. The results showed that HRP was pressure-resistant and HRP activities were decreased respectively by 2.36%, 5.69% and 10.36% with the increase of the above pressure. The contents of -helix, -sheet and random coils in HRP were all increased by less than 4%, while the content of -turn was significantly decreased by over 11%. After HRP was processed by high pressure, the HRP fluorescence intensities at the excitation spectra peak of 234 nm and emission spectra peak of 308 nm were decreased respectively by 18.28%, 5.46% and 4.04%. The fluorescence intensity of HRP treated at 100 MPa, 15 min was decreased to the largest extent. The results showed that high pressure processing obviously inactivated the activity of horseradish peroxidase that was related to its structural changes.