Interactions between unfolding/disassembling behaviors, proteolytic subfragments and reversible aggregation of oxidized skeletal myosin isoforms at different salt contents
Interactions between unfolding/disassembling behaviors, proteolytic subfragments and reversible aggregation of oxidized skeletal myosin isoforms at different salt contents
复制标题
不同盐含量下氧化骨骼肌球蛋白亚型的展开/分解行为、蛋白水解亚片段和可逆聚集之间的相互作用
DOI：
10.1016/j.foodres.2022.111449
复制
发表时间：
2022
影响因子：
8.1
通讯作者：
Xiaoyan Tang
中科院分区：
文献类型：
--
作者：
Min Zhang;Chengliang Li;Yuemei Zhang;Lichao He;Wei Li;Mengling Zhang;Jiajing Pan;Shuangjia Huang;Youming Liu;Yan Zhang;Yongguo Jin;Jinxuan Cao;Guofeng Jin;Xiaoyan Tang
·盐是氧化肌球蛋白溶胀/再水化的关键驱动力。·肌球蛋白S1和HMM亚基在1-2%盐含量下经历肽氧化断裂和可逆组装。·高达5%的盐水浸泡极大地诱导了肌球蛋白杆部分交联的溶解和稳定。· >3%的盐改善了热凝胶化过程中氧化肌球蛋白的弹性和宏观粘度。肌球蛋白丝在腌制肉制品加工过程中起着捕水和热力学调节的重要作用。受盐影响的蛋白水解/抗氧化酶的氧化还原状态和可用性可能改变肌球蛋白的离子结合能力，从而导致肿胀和再水化。因此，本研究考察了不同盐含量（0%、1%、2%、3%、4%、5% NaCl）和体外氧化（10 mM H2 O2/抗坏血酸基羟基自由基（OH）产生体系）对猪肌球蛋白的氧化稳定性、溶解/分散能力、糜蛋白酶消化率、聚集位点和微观流变学特性的影响。结果表明，2%盐溶液浸泡使变性肌球蛋白的巯基暴露增多，二硫键的形成受到抑制，分散结构变小（直径在10-50 nm之间），Ca 2+ -ATP酶活性提高。因此，凝胶电泳显示肌球蛋白S1和HMM亚基高度氧化，并且容易发生可逆组装。尽管在3%盐含量下溶胀的肌球蛋白之间的疏水相互作用增强，但≥4%盐极大地促进了色氨酸和交联结构的暴露/极化，主要发生在肌球蛋白S2部分。微观流变学结果表明，在高离子强度（≥4%盐）条件下，氧化肌球蛋白形成了更紧密的热定型网络，从而增加了液滴间阻力和宏观粘度。这项工作有望为改善工程肌肉食品的质地和功能提供一些有用的见解。
• Salting is the key driving force toward swelling/rehydration of oxidized myosin. • Myosin S1 and HMM subunits undergo both peptide oxidative scission and reversible assembling at 1–2% salt content. • Up to 5% salt brining greatly induced solubilization and stabilization with cross-linkages at myosin rod portion. • >3% salt improved elasticity and macroscopic viscosity of oxidized myosin during thermal gelation. Myosin filament plays a critical role in water-trapping and thermodynamic regulation during processing of brined muscle foods. The redox state and availability of proteolytic/antioxidant enzymes affected by salt may change the ion-binding capacity of myosin consequently contributing to swelling and rehydration. Thus, this study investigated the impact of different salt content (0%, 1%, 2%, 3%, 4%, 5% NaCl) and oxidation in vitro (10 mM H 2 O 2 /ascorbate-based hydroxyl radical ( OH)-generating system) on the oxidative stability, solubility/dispersion capacity, chymotrypsin digestibility, aggregation site and the microrheological properties of isolated porcine myosin. The result showed that, brining at 2% salt exposed more sulfhydryl groups and inhibited the formation of disulfide bond, whereby smaller dispersed structure (diameter within 10–50 nm) and higher Ca 2+ -ATPase activity of the denatured myosin were observed. Accordingly, gel electrophoresis showed that myosin S1 and HMM subunits were highly oxidized and susceptible to reversible assembles. Despite enhanced hydrophobic interactions between swelled myosin at 3% salt content, ≥4% salt greatly promoted the exposure/polarization of tryptophan and cross-linking structures, mainly occurring at myosin S2 portion. The results of micro-rheology proved that oxidized myosin formed a tighter heat-set network following rehydration at high ion strength (≥4% salt), suggesting an increased inter-droplet resistance and macroscopic viscosity. This work is expected to give some useful insights into improved texture and functionality of engineered muscle foods.