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