The effect of radio frequency heating on the inactivation and structure of horseradish peroxidase. (1st January 2023) - Yao, Yishun
Highlights: RF heating inactivates HRP at 70 °C and 90 °C. RF heating changes the secondary and tertiary structures of HRP. Conformational deterioration is responsible for the enzyme inactivation. Conformational changes of enzyme vary with temperature and electrode gap. Abstract: The effects of radio frequency (RF) heating on horseradish peroxidase (HRP) activity and its structure were investigated in this paper. The HRP was heated to 50 °C, 70 °C and 90 °C at different electrode gaps (100, 110 and 120 mm). The relative enzyme activity was 105.33 %–113.73 % at 50 °C, 91.11 %–93.05 % at 70 °C and 47.05 %–68.17 % at 90 °C. Ultraviolet–visible, circular dichroism and fluorescence spectra were used to monitor the variation in secondary and tertiary structure. The results showed that RF heating at the electrode gaps of 120 mm contributed to more severe enzyme inactivation and conformational destruction, which can be explained by the changes in Soret band, secondary structure content and tryptophan fluorescence intensity. This study revealed that enzyme inactivation by RF heating was associated with loss of helical structure, unfolding of enzyme protein and ejection of heme group.