Phosphorproteome Changes of Myofibrillar Proteins at Early Post-mortem Time in Relation to Pork Quality As Affected by Season

The effect of season on phosphorylation of myofibrillar proteins and meat quality of pork longissimus muscles was investigated. Muscle samples were obtained from 40 pork carcasses (10 for each season) at 45 min and 3 and 9 h post-mortem. Myofibrillar proteins were extracted, separated by SDS-PAGE, quantified by phosphor-specific staining, and finally identified by LC-MS/MS. Muscle pH, glycogen, and ATP were measured, and pale, soft, and exudative (PSE) meat was identified by pH value at 45 min post-mortem. A total of 23 bands were detected on SDS-PAGE gels. The phosphorylation levels of bands did not differ between PSE and normal meat. However, the phosphorylation levels of 22 bands were significantly changed by season. Nine of them showed different changes from 45 min to 9 h post-mortem, which were identified to be involved in energy metabolism and sarcomere contraction. Correlation analysis indicated the regulatory progress of these proteins during rigor mortis. These observations contribute to a better understanding of the biochemical processes for the conversion of muscle to meat varying with season.本研究探讨了季节对猪背最长肌（pork longissimus muscles）肌原纤维蛋白（myofibrillar proteins）磷酸化水平及肉品质的影响。实验采集40份猪胴体的肌肉样品，每个季节各10份，采样时间分别为宰后45 min、3 h及9 h。提取肌原纤维蛋白后，通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）进行分离，采用磷酸化特异性染色完成定量，最终通过液相色谱-串联质谱（LC-MS/MS）鉴定蛋白种类。检测肌肉的pH值、糖原及ATP含量，并以宰后45 min的pH值作为苍白柔软渗出性（PSE）肉的判定依据。在SDS-PAGE凝胶上共检测到23个条带，PSE肉与正常肉的条带磷酸化水平无显著差异。但有22个条带的磷酸化水平随季节发生显著变化，其中9个条带的磷酸化水平在宰后45 min至9 h期间呈现特异性变化趋势，经鉴定这些条带对应的蛋白参与能量代谢与肌节收缩过程。相关性分析揭示了此类蛋白在尸僵过程中的调控进程。本研究结果有助于深入理解不同季节下肌肉转变成肉的生化机制。