A RE‐EXAMINATION OF MUSCLE PROTEIN SOLUBILITY

Abstract

ABSTRACTMuscle proteins are conveniently characterized by their solubility properties. Sarcoplasmic proteins are defined as those soluble when muscle is extracted with water or solutions of low ionic strength, i.e., physiological or less. Myofibrillar proteins are generally thought to be soluble at elevated ionic strengths (> 0.3). Close examination of the extractability and solubility properties of these two groups of proteins, indicates that their solubility properties are not as different as is generally believed. With both groups of proteins, distinctions must be made between extractability and solubility. Our research results have revealed that the proteins of eight different white muscles are essentially completely soluble in solutions of physiological ionic strength or less and neutral pH. Six of these muscles were from white fleshed fish, and one each was from a fatty fish and chicken breast muscle. There were differences among the muscles of the various species. In mackerel and chicken breast muscle, it appeared that certain proteins had to be removed before the remaining myofibrillar proteins could be solubilized in water.