Identification of myosin heavy chain isoforms in porcine longissimus dorsi muscle by electrophoresis and mass spectrometry.

Myosin heavy chain (MHC) isoforms have been considered as makers for muscle fiber types in relation to meat quality, whereas MHC isoforms in porcine skeletal muscle have not been fully identified. The improved technique of SDS-PAGE and 2DE were used to separate porcine MHC isoforms. Western blotting with monoclonal antibodies including BA-F8 (anti-MHC slow/I), SC-71 (anti-MHC 2a and 2x), 10F5 (anti-MHC 2b), and BF-35 (anti-MHC slow/I and 2a) and MS were used to confirm MHC migration rate and identify MHC isoforms from separated bands and spots. Up to 45% w/v of glycerol, 8% w/v of acrylamide content, and 25 h of electrophoretic time at 70 V allowed a clear separation of MHC isoforms. Major MHC isoforms such as slow, 2a, 2x, and 2b were clearly separated by SDS-PAGE. A total of 23 MHC spots were separated and identified by 2DE and MS. Therefore, four MHC isoforms such as slow/I, 2a, 2x, and 2b could be identified by the improved SDS-PAGE technique, 2DE and MS. Therefore, these techniques allow more accurate and accessible analysis in muscle fiber typing and in relationship between MHC isoforms, muscle fiber characteristics, and pork quality.