Effect of electrical stimulation on postmortem titin, nebulin, desmin, and troponin-T degradation and ultrastructural changes in bovine longissimus muscle

摘要: Electrical stimulation (ES) of bovine carcasses is usually done to increase tenderness and has been hypothesized the activity proteolytic enzymes that may degrade structural proteins in muscle cells cause fractures breaks fibers, thus enhancing meat tenderness. Our objective was compare postmortem (PM) changes proteins, titin, nebulin, alpha-actinin, desmin, troponin-T myofibrillar structure nonstimulated (NS) ES skeletal muscle. One side eight beef stimulated within 1 h death, other NS control. Myofibrils for SDS-PAGE samples transmission electron microscopy were prepared from longissimus at 0, 1, 3, 7, 14, 28 d PM. In SDS-PAGE, titin migrated as three bands both 0-d samples. The slowest migrating band, T1 (intact titin), decreased slightly faster five animals. fastest T2 (degraded increased amount through 3 still present d. A monoclonal antibody (mAb) identified a large family degradation products than myosin heavy chains more heavily labeled Western blots samples, intact nebulin disappeared by animals, 7 four 14 one animal, but band absent animals showed desmin sooner two earlier sample corresponding control Blots with polyclonal 38-kDa product Postmortem alpha-actinin not detected. Contraction node (CN) formation, stretching conjoined sarcomeres adjacent nodes, frequency I-band accelerated appearance wide Z-line, and, some characteristics