Preparation and purification of myosin from human tracheal smooth muscle.

NaCl myosin was prepared from the annular smooth muscles of human bronchus. About 7 mg of gel filtered myosin was gained from 8 g minced tracheal muscle of the younger subject. The yield from the older (74-year old) subject was only 30% of that from the younger subject, even though the starting material was more (12 g minced tissue). Tracheal myosin contains P lipid in considerable amount; P lipids account for some 28% of the total phosphate content of the myosin, and even more (50-55%) in the case of the older subject. The preparation could be phosphorylated only in the presence of CAMP and PGF2 alpha, respectively. Cu2+ treatment liberated less phosphate when compared with myosin preparations from other smooth muscles; however, the majority of the phosphate bonds underwent hydrolysis upon the effect of KOH. The reactions specific for amino acids, and also other observations allow the conclusion that the majority of covalently bound phosphate is present in an ester-type bond. Lysine-vasopressin, and also diethylpyrocarbonate successfully protect the P content of myosin from the hydrolysis inherent to incubation.