Some properties of myofibrillar proteins from thawed muscles

1. 1. Ammonium sulphate salting-out curves of myofibrillar proteins prepared from muscles in contracture after thawing show that most of Dubuisson 's γ-myosin corresponds to a component which precipitates at 12–18% of saturation. The same results have been obtained in muscles in rigor mortis. 2. 2. The presence of increased amounts of γ-myosin in the myofibrillar-protein solutions causes a decrease of ATPase activity and a lower viscosity. 3. 3. The extractability of the myofibrillar proteins is strongly decreased in contracture after thawing; nevertheless, the increase of γ-myosin seems to be only relative.