The chromatography of the meromyosins on diethylaminoethylcellulose.

In a previous chromatographic study of rabbit L-myosin (Perry, 1960) the distribution of adenosine-triphosphatase activity in the main eluted fraction of this protein did not appear to be compatible with enzymic homogeneity. Brahms (1959, 1960) has also reported the separation of components of different adenosine-triphosphatase activity from rabbit myosin. The relation of these findings to the subunit structure of myosin is far from clear but they suggested that re-investigation of the distribution of adenosine-triphosphatase activity between the light and heavy meromyosins (Szent-Gyorgyi, 1953; Gergely, 1953; Mihalyi & Szent-Gyorgyi, 1953) might throw some light on this problem. There is accumulating evidence of the heterogeneity of the meromyosins (Lowey & Holtzer, 1959; Fryar & Gibbs, 1960; Szent-Gyorgyi, Cohen & Philpott, 1960) and the solubility properties of heavy meromyosin compared to myosin and to light meromyosin make this protein particularly suitable for chromatographic studies with diethylaminoethylcellulose. The present paper is concerned with a chromatographic investigation of the standard light and heavy meromyosin preparations and the distribution of adenosine-triphosphatase activity in the fractions which can be isolated from these proteins. Evidence is presented which suggests that fragments, other than heavy meromyosin, which result from tryptic digestion of myosin, possess appreciable adenosine-triphosphatase activity. A preliminary note of some of the findings reported here has appeared earlier (Mueller & Perry, 1960).