Mechanism by Which Oxidative Phosphorylation Regulates the Color Stability of Tan Sheep Meat during Postmortem Storage

In order to clarify the mechanism underlying the regulatory effect of oxidative phosphorylation (OXPHOS) on the color stability of Tan sheep meat during postmortem storage, the M. longissimus dorsi of 6-month-old Tan sheep was stored at 4 ℃ after slaughter and evaluated for the activity of endogenous antioxidant enzymes and the content of reactive oxygen species (ROS) after 0, 4 and 8 days. Proteomics based on isobaric tags for relative and absolute quantitation (iTRAQ) was used to study protein expression in Tan sheep meat at different storage times. The results showed that during 0–8 days of storage, the activity of endogenous antioxidant enzymes showed a decreasing trend (P < 0.05), and the ROS content significantly increased with storage time (P < 0.05). Eight differentially expressed proteins were identified as the core proteins affecting the color stability of Tan sheep meat, namely ATP synthase F1 subunit alpha (ATP5A1), ATP synthase peripheral stalk subunit OSCP (ATP5O), ATP synthase peripheral stalk subunit D (ATP5H), cytochrome c oxidase subunit II (COX2), cytochrome c oxidase subunit 5A (COX5A), succinate dehydrogenase complex iron sulfur subunit B (SDHB), ADP/ATP translocase 1 (SLC25A4), and cytochrome c (CYCS). These proteins affected the color stability of Tan sheep meat mainly through the energy metabolism and redox processes. These results indicated that the loss of the activity of antioxidant enzymes in Tan sheep meat during postmortem storage caused the accumulation of ROS, which led to the destruction of the mitochondrial integrity of muscle cells and aberrant gene expression of complex subunits such as ATP5A1, ATP5O, ATP5H, COX2, COX5A, SDHB, SLC25A4 and CYCS in the oxidative phosphorylation pathway, thus contributing to changes in the structure and function of mitochondrial complexes and blockage of the oxidative phosphorylation process, and ultimately affecting the color stability of Tan sheep meat.