蛋白质氧化是引起肉类品质劣变的重要因素之一，与畜禽肉类相比，鱼肉肌原纤维蛋白及不饱和脂肪酸含量丰富，较易受活性氧自由基的攻击，发生蛋白质的氧化。目前蛋白氧化研究主要集中于蛋白质层次，如二硫键、羰基化合物生成及蛋白质的氧化聚集等，而氨基酸层次下的氨基酸侧链氧化产物、氧化位点、后续氧化路径及机制等科学问题有待阐明。本项目以我国主要淡水鱼（草鱼、鳙鱼）为原料，研究不同贮藏过程鱼肉体系中活性氧含量、氧化还原酶系统活性、蛋白氧化的动态变化，探究它们之间的内在关系；研究鱼肉蛋白中谷氨酸等的羰基化产物及半胱氨酸等的氧化修饰产物的变化规律，筛选鱼肉蛋白质羰基化及氨基酸侧链氧化的特定标记物；利用定量蛋白质组学等技术，评价鱼肉贮藏过程蛋白质发生氨基酸氧化修饰的肽段丰度等指标的变化，明确主要氨基酸的氧化位点，揭示淡水鱼肉体系中基于氨基酸侧链氧化的蛋白氧化分子机制，为淡水鱼肉贮藏过程品质控制技术的建立开辟新思路。

Protein oxidation has been gradually regarded as an important factor for quality deterioration in meat products. Compared with other meat sources, fish are highly susceptible to protein oxidation due to the abundant polyunsaturated fatty acids and myofibrillar proteins. Current research on protein oxidation mainly focused on the protein level, such as the formation of disulfide bonds, carbonyls, and protein aggregates, however, protein oxidation and its oxidative products, oxidative process, and oxidative sites at amino acid level were less understood. Hence, this project selects grass carp (Ctenopharyngodon idellus) and bighead carp (Aristichthys nobilis), two major freshwater fish in China, to evaluate the dynamic changes about the contents of reactive oxygen species, activity of antioxidant enzyme systems, myofibrillar/sarcoplasmic protein oxidation during storage as well as their intrinsic relationships. Changes in derived carbonylation and oxidative products of glutamine, cysteine, etc. will be characterized and further chosen as specific oxidative markers of protein oxidation. The oxidative sites of amino acid side chains and its related pathways will be revealed by quantitative proteomics via the analysis of intensities of oxidative modified peptides. Overall, this project is designed to lay a molecular basis of protein oxidation based on oxidative modification of amino acids and a better understanding of protein oxidation in freshwater fish, which would provide a theoretical basis for the control of fish quality.