Interaction of fish myoglobin and myofibrillar proteins.

Interactions between fish myoglobin (Mb) and myofibrillar proteins were investigated in a Mb-natural actomyosin (NAM) model at 4 degrees C. Increases in metmyoglobin (MetMb) formation and the relative content of bound Mb were observed, as were decreases in whiteness and Ca(2+)-ATPase activity (P < 0.05). During the first 6 h of incubation, Mb bound preferably to myosin at domains other than the head portion, as evidenced by measurable ATPase activity. The potential binding of Mb to myosin heads occurred after 24-h incubation as evidenced by the marked decrease in Ca(2+)-ATPase activity of the NAM-Mb mixture when compared to that of NAM alone (P < 0.05). The interaction between fish Mb and myofibrillar proteins was more pronounced with increased storage time; formation of high-molecular-weight aggregates (> 206 kDa) also increased with time. Electrophoretic study revealed that disulfide bonds were not involved in Mb-NAM interactions.