Changes in degradation and phosphorylation level of titin in three ovine muscles during postmortem

Ying Wang, Xin Li, Zheng Li, Meng Li, Jie Zhu, Dequan Zhang

Index: 10.1111/ijfs.13663

Full Text: HTML

Abstract

Summary The objective of this study was to investigate the degradation of titin and its phosphorylation level in three muscles from sheep. The MFI and pH from the longissimus lumborum (LL), semimembranosus (SM) and psoas major (PM) muscles were measured at 30 min, 1, 2, 7, 14, 21 and 28 days postmortem. Myofibrillar proteins were extracted, separated by SDS-PAGE and quantified by phosphor-specific staining. Phosphorylation of titin was predicted by Pro-Q Diamond-SYPRO Ruby staining. Two days after exsanguination, the pH and MFI of the PM were higher than those of the LL and SM muscles (P < 0.05). The sarcomere length of the PM muscle was also longer than that of the LL and SM muscle (P < 0.05). PM muscles had a highest phosphorylation level (P < 0.05) at 0.5 h postmortem and showed the greatest degree of titin degradation over 28 days. This suggests that phosphorylation of titin might accelerate its degradation. Proteolysis of titin and the phosphorylation of the protein were determined by SDS-PAGE and Pro-Q Diamond-Ruby staining, respectively. The analysis indicated the fastest degradation of titin was detected in the PM muscles which had a highest phosphorylation level. This suggests that phosphorylation of titin might accelerate its degradation.