Abstract：
This study investigated the cryoprotective mechanism of ultrafiltration membrane-separated fractions (>10 kDa, UF-1; 3-10 kDa, UF-2; and <3 kDa, UF-3) derived from silver carp hydrolysates on frozen surimi. The surimi gel incorporating UF-3 exhibited a compact, continuous structure with uniform pores, even after undergoing six freeze-thaw (F-T) cycle, with the minimal reduction in entrapped water (from 95.1 % to 91.1 %) and least increase in free water (from 4.5 % to 6.6 %) as revealed by SEM and LF-NMR analysis. Through molecular docking analysis, three major peptides in UF-3 were identified to form robust interactions with the myosin head pocket, facilitated by hydrogen bonds, electrostatic forces, and hydrophobic interactions. Furthermore, molecular dynamics simulations demonstrated that the three peptides effectively prevented myosin from unfolding and aggregating by tightly binding to basic amino acids (Arg, Lys) and hydrophobic amino acids (Phe, Leu, Ile, Met, and Val) residues in the myosin head pocket, primarily governed by electrostatic energies (-156.95, -321.38, and -267.53 kcal/mol, respectively) and van der Waals energies (-395.05, -347.46, and -319.16 kcal/mol, respectively). Notably, the key action site was identified as Lys599 on myosin. The hydrophilic and hydrophobic hotspot residues of the peptides worked synergistically to stabilize the myosin structure in frozen surimi.
摘要：
这项研究研究了超滤膜分离级分（>10kDa，UF-1;3-10kDa,UF-2;和<3kDa，UF-3）来自冷冻鱼糜上的鲤鱼水解产物。掺入UF-3的鱼糜凝胶表现出致密，具有均匀孔隙的连续结构，即使在经历了六个冻融（F-T）循环之后，SEM和LF-NMR分析显示，截留水的减少最少（从95.1％到91.1％），游离水的增加最少（从4.5％到6.6％）。通过分子对接分析,UF-3中的三种主要肽被鉴定为与肌球蛋白头袋形成强大的相互作用，由氢键促进，静电力，和疏水相互作用。此外，分子动力学模拟表明，这三种肽通过紧密结合碱性氨基酸（Arg，Lys）和疏水性氨基酸（Phe，Leu,Ile,Met,和Val）肌球蛋白头袋中的残留物，主要受静电能(-156.95、-321.38和-267.53千卡/摩尔，分别)和范德华能量(-395.05、-347.46和-319.16千卡/摩尔，分别)。值得注意的是,关键作用位点被确定为肌球蛋白Lys599.肽的亲水性和疏水性热点残基协同作用以稳定冷冻鱼糜中的肌球蛋白结构。
