LC MS/MS identification of large structural proteins from bull muscle and their degradation products during post mortem storage

Large proteins (>100 kDa) in bovine M. longissimus dorsi and their degradation products during post mortem ageing were investigated by gel electrophoresis and LC-MS/MS analysis. Seventeen protein bands from SDS-PAGE were analysed and 26 proteins were identified. Intact titin, nebulin and filamin were shown to break down during post mortem ageing of meat. A number of myosin super-family members were revealed on SDS-PAGE. Myosin heavy chain 1 (MYH1), myosin heavy chain 2 (MYH2), and myosin heavy chain 7 (MYH7) were distributed broadly across the bands in the forms of cross-linked/aggregated polymers, and also as fragments. Three myomesin family members: myomesin 1 (185 kDa isoform 1), myomesin (M-protein) 2, 165 kDa, and myomesin family member 3, were identified in the muscle samples. Several other proteins such as synemin, myosin binding protein C (C-protein), glycogen debranching enzyme and ryanodine receptor 2 were also identified.