Relationship between the myofibrillar protein gel strengthening effect and the composition of sarcoplasmic proteins from Pacific mackerel [Scomber japonicus]

To determine which protein bands that appeared in SDS-polyacrylamide gel electrophoresis (PAGE) patterns of sarcoplasmic proteins (Sp-P) are responsible for the gel strengthening effect of Sp-P on the myofibrillar protein (Mf-P) gel, the relations between the jelly strength of Mf-P gel added with each of three different sarcoplasmic fractions and the relative amounts of protein bands in the SDS-PAGE pattern of each sarcoplasmic fraction were examined. The heat-coagulability of each sarcoplasmic fraction was highly correlated with the jelly strength of each gel. Relative amounts of 94, 64, and 40 kDa components in the SDS-PAGE pattern of each sarcoplasmic fraction also showed a good correlation with the jelly strength of gel. These results suggest that the high jelly strength of Sp-P added Mf-P gel is attributable to a large amount of heat-coagulable proteins, especially the 94, 64, and 40 kDa components of Sp-P.