Separation and qualitative recovery of major proteins from a single sample of skeletal muscle.

The major soluble and myofibrillar proteins of skeletal muscle were separated into five fractions by extracting a single sample with solutions of increasing ionic strength and pH. After separation of myoglobin, other soluble proteins, and myosin, an acetone powder was prepared from the residue; the extractions were continued to yield actin and the troponin-tropomyosin complex. From 200 g of skeletal muscle the average recoveries were: total sarcoplasmic proteins, 4.5 g; myoglobin, 0.55 g; myosin, 2.7 g; actin, 0.1 g; and troponin-tropomyosin complex, 17.5 mg. The method was designed for investigating the effects of physical or chemical treatment of whole muscle or whole animals by monitoring changes in individual muscle proteins. This is particularly desirable for comparisons of amino acid composition, since naturally occurring levels of methylated histidine and lysine vary in vertebrate muscle among species, among individual members of a species, and among muscle types.