SOLUBILITY OF THE PROTEINS OF MACKEREL LIGHT MUSCLE AT LOW IONIC-STRENGTH

Over 90% of the proteins of mackerel light muscle were soluble in solu tions of physiological ionic strength or less. To accomplish this solu bilization, it was necessary to extract certain proteins at moderate i onic strength and neutral pH before extracting the rest of the myofibr illar and cytoskeletal proteins in water. Six proteins were favorably solubilized by sodium chloride solutions of moderate ionic strength at neutral pH under conditions that allowed later dissolution of myofibr illar and cytoskeletal proteins in water. The possibility is suggested that three of these proteins were involved in preventing the solubili zation in water of other myofibrillar and cytoskeletal proteins of mac kerel light muscle, Based on molecular masses and relative abundance, these proteins could possibly be M-protein (166 kDa), alpha-actinin (9 5 kDa) and desmin (56 kDa).