Comparison of the activities and cryoprotective mechanism of two antifreeze peptides derived from silver carp parvalbumin

Abstract

Objective: Explore the cryoprotective mechanism and structure-activity relationship of antifreeze peptides derived from silver carp parvalbumin. Methods: Using differential scanning calorimetry and molecular dynamics simulation to compare activity, structure and mode of action of two typical peptides. Results: Pv-AFP 1 （KAADSFNH KAFFAKVG） had a stable α-helix structure, while Pv-AFP 2 （KAADSFNHKAF） tended to exhibit random coil. The thermal hysteresis activity of Pv-AFP 1 was 0.87 ℃, which was higher than Pv-AFP 2 （0.74 ℃）. Molecular dynamics simulations showed that Pv-AFP 1 could interact with 53 water molecules, and could form 16 hydrogen bonds to adsorb onto the surface of ice crystals, with a binding energy of -1 514 kJ/mol, all were greater than Pv-AFP 2 （can bind 50 water molecules, adsorb on ice surface by forming 11 hydrogen bonds, with a binding energy of -805 kJ/mol）. Despite the similarity of the two peptide sequences, their major sites and modes of interactions with water molecules and ice crystals were somewhat different. In addition, both peptides could interact with ice/water interface and altered the curvature of the ice surface, thereby inhibiting water freezing. But Pv-AFP 1 showed a better inhibitory effect on ice surface growth than Pv-AFP 2, which was consistent with their thermal hysteresis activity. Conclusion: The activities of antifreeze peptides derived from silver carp parvalbumin might be related to their structural characters and their affinities, sites and modes of interaction with water molecules and ice crystals.

Keywords

• silver carp
• parvalbumin
• antifreeze peptide
• thermal hysteresis
• molecular dynamic