Phosphoproteome analysis of sarcoplasmic and myofibrillar proteins in bovine longissimus muscle in response to postmortem electrical stimulation

Protein phosphorylation changes of the sarcoplasmic and myofibrillar proteins in beef longissimus muscle in response to electrical stimulation (ES) was investigated. Sarcoplasmic and myofibrillar proteins purified from muscle samples taken at 0, 3 and 10 h after ES were separated on SDS-PAGE and stained with phosphorous and protein specific stains. There was a significant effect of ES on phosphorylation of total sarcoplasmic and myofibrillar proteins (P < 0.05). However, although there an instant effect of ES on the phosphorylation level of the myofibrillar proteins, the ES effect on the sarcoplasmic proteins (P < 0.05) was first observed after 3 h. Several protein bands were analyzed by LC-MS/MS, revealing that the major glycolytic proteins, including glycogen debranching enzyme, glycogen phosphorylase and 6-phosphofructokinase probably are affected by ES together with different heat shock proteins. This work gives an insight into the regulation of the glycolytic enzymes and muscle contraction on application of electrical stimulation.