Fish Myosin Aggregation as Affected by Freezing and Initial Physical State

Fish myosin obtained from Tilapia nilotica was solubilized in 20 mM Tris‐HCl, pH 7.0, with 0.6 M KCl (solution model system), or suspended without salt (suspension model system). Changes in % soluble protein, Ca 2+ ‐ATPase activity, and total and reactive ‐SH groups during frozen storage were evaluated. Frozen induced aggregation of fish myosin showed different behavior depending upon its initial physicochemical state. When myosin was solubilized prior to frozen storage, head‐to‐head interactions seemed to be more involved in protein aggregation with a strong participation of disulfide bonds. On the contrary, a preferentially side‐to‐side mechanism might be involved in the aggregation of myosin upon suspension, with a minor interaction of ‐SH groups.