Sarcoplasmic and myofibrillar proteins in white trunk muscle of salmon (Salmo salar) after estradiol treatment

Abstract 1. 1. Proteins from skeletal muscle of Atlantic salmon ( Salmo salar ) were separated into two fractions, sarcoplasmic and myofibrillar, the sarcoplasmic proteins amounting to 47%. 2. 2. The actomyosin linkage of the myofibrillar proteins was broken by adding ATP MgCl 2 and myosin was brought into solution in high ionic strength buffer. 3. 3. The method was applied to fish treated with 17-β estradiol. The sarcoplasmic protein content per g wet wt or per mg of DNA was unchanged. The myofibrillar proteins decreased by 17%. Myosin heavy chain decreased to a simila extent as the total myofibrillar proteins. 4. 4. The advantage of the methods described is to relate changes in muscle protein metabolism to specific physiological functions of the tissue.