Proteome changes in bovine longissimus thoracis muscle during the first 48 h postmortem: shifts in energy status and myofibrillar stability.

Changes in the insoluble protein fraction of bovine longissimus thoracis muscle from eight Norwegian Red (NRF) dual-purpose young bulls during the first 48 h postmortem were investigated by two-dimensional gel electrophoresis (2DE) and matrix-assisted laser desorption ionization−time of flight tandem mass spectrometry (MALDI−TOF MS/MS). Significant changes were observed in a total of 35 proteins, and of those, 26 were identified and divided into three different groups: metabolic enzymes, cellular defense/stress proteins, and structural proteins, according to their predicted function. The majority of the metabolic enzymes identified are involved in the energy metabolism of the cell, while the cellular defense/stress proteins can be related to regulation and stabilization of the myofibrillar proteins. Both easily soluble proteins as well as structural proteins were identified in the insoluble protein fraction. We have studied the changes in solubility during postmortem storage by comparing the postmortem ch...