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

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 MgCl₂ 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.