Changes in the activity, dissociation, aggregation, and the secondary and tertiary structures of a thaumatin-like protein with a high polyphenol oxidase activity induced by high pressure CO2

• The PPO activity of TLP after HPCD was initially increased and then decreased.
• HPCD-induced dissociation and aggregation of the native TLP aggregates.
• HPCD caused dissociation of larger aggregates and aggregation of smaller aggregates.

Effects of high pressure CO2 (HPCD) on the activity, dissociation and aggregation, as well as secondary and tertiary structures of a thaumatin-like protein (TLP) with polyphenol oxidase (PPO) activity from apples (Malus domestica, Fuji) were investigated. The PPO activity of TLP subjected to HPCD was initially increased and then decreased after increasing pressure, temperature, time and cycles. The secondary structure was changed by HPCD. The λmax of fluorescence spectra was red-shifted with intensity increasing or decreasing, depending on the treatment parameters. HPCD induced dissociation and aggregation of the native TLP aggregates. More intense HPCD treatment caused the dissociation of larger aggregates and further aggregation in the smaller aggregates. Activation of TLP may be attributed to the dissociation of its aggregates and the structural changes at the catalytic centre; inactivation was due to the aggregation of TLP and collapse of the catalytic centre.Industrial relevanceHigh pressure carbon dioxide (HPCD) is one merging non-thermal technique for inactivating microorganisms and enzymes in food products. Polyphenol oxidase (PPO) can cause quality deterioration in many food products. This study analyzed the effects of HPCD on the activity, dissociation, aggregation, and the secondary and tertiary structure of a thaumatin-like protein (TLP) with a high PPO activity. Available data provided in this study will benefit the food industry.