Trehalose and alginate oligosaccharides affect the stability of myosin in whiteleg shrimp (Litopenaeus vannamei): The water-replacement mechanism confirmed by molecular dynamic simulation

Abstract

Myosin in shrimp (Litopenaeus vannamei) is prone to denaturation and is affected by freezing and frozen storage. Previous studies indicated that cryoprotective trehalose (TR) and alginate oligosaccharides (AO) greatly slowed the degradation of myofibrillar proteins and reduced mechanical damage on shrimp muscle tissues. In this study, homology modeling and 60 ns of molecular dynamic (MD) simulations were conducted in order to investigate the conformation variations of myosin in 0.03 g/mL TR and AO systems. Ramachandran plot for the myosin model established by Modeller program revealed that 91.9% of all amino acid residues were in the most favored regions. After MD simulations, it was found that the incorporated TR/AO were generally close to myosin and combined with amino acid residues via electrostatic interactions and hydrogen bonds. The combination of TR/AO replaced partial water molecules around myosin surface, thereby improving the cooperativity and consistency of the myosin heavy and light chain (MHC and MLC) motions. This decreased the flexibility of myosin chains and reduced the risk of protein aggregation, stabilizing the conformational structure of myosin in the systems. Finally, the water-replacement mechanism induced by TR/AO molecules was confirmed to predominantly contribute to the stability of shrimp myosin in the simulated systems.