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, Ca2+-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.