Low molecular weight components (g-chains) of myosin from rabbit skeletal muscle. Separation, amino acid compositions and contents in myosin.

Low molecular weight components (g1, g2, and g3) were isolated from rabbit skeletal muscle myosin and their amino acid compositions were analyzed. One mole tryptophan was found in g1 and in g2, but none in g3. One mole of acetic acid was found per mole of each g-chain and it was concluded that the N-terminal groups of all three g-chains are acetylated. The minimum molecular weight of the g-chains were estimated from their amino acid compositions. It was estimated by SDS-disc electrophoresis that 1 mole of myosin contained 0.90, 1.7, and 0.63 moles of g1, g2, and g3, respectively. Similar values were obtained with psoas muscle myosin, but in heavy meromyosin prepared from skeletal muscle myosin the content of g2 was much lower, and that of g3 was much higher.