Structural studies and molecular dynamic simulations of polyphenol oxidase treated by high pressure processing

Area of Science:

• Food Science
• Biophysics
• Biochemistry

Background:

• High pressure processing (HPP) is a non-thermal method impacting enzyme activity.
• Polyphenol oxidase (PPO) is crucial in food browning, and its response to HPP needs molecular-level understanding.
• Previous studies show varied effects of HPP on PPO, but conformational changes remain unclear.

Purpose of the Study:

• To elucidate the molecular-level conformational changes of PPO under high pressure.
• To investigate the impact of different pressure levels (200 MPa and 600 MPa) on PPO structure and active site.
• To correlate computational findings with experimental spectroscopic data.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model PPO behavior under varying pressures.
• Spectroscopic experiments were conducted to validate simulation results.
• Molecular docking was used to assess substrate binding affinity at different pressure conditions.

Main Results:

• High pressure reduced PPO volume and hydrogen bonds, inducing active center alterations and loop movements.
• At 200 MPa, PPO's active pocket became exposed and the substrate channel widened.
• At 600 MPa, the active pocket shifted inward, narrowing the substrate channel, and reducing binding affinity.

Conclusions:

• HPP induces distinct conformational changes in PPO dependent on pressure intensity.
• The observed structural modifications under high pressure directly influence PPO's substrate binding capabilities.
• Findings align with experimental data, providing a molecular basis for HPP effects on PPO activity.