Abstract: In order to investigate the mechanism of high pressure carbon dioxide (HPCD) and ultra-high pressure inactivating polyphenol oxidase (PPO) and pectin methylesterase (PE), SDS-PAGE, infrared spectroscopy, and fluorescence spectroscopy were applied to study the structural change of PPO and PE after the treatments. After HPCD and ultra-high pressure treatments for 60 min, the activity of PPO and PE decreased as the pressure ascent in the investigated range. SDS-PAGE analysis showed that no peptide chains were cut off, but according to the infrared and fluorescence spectral profiles the protein secondary and tertiary structures of the two enzymes were changed after the treatments. Hence, HPCD and ultra-high pressure inactivate PPO and PE through changing their advanced structures.

Key words: high pressure carbon dioxide (HPCD), ultra-high pressure, polyphenol oxidase (PPO), pectin methylesterase (PE), structure