STUDIES ON ADENOSINETRIPHOSPHATASE OF MUSCLE * III. THE LIPOPROTEIN NATURE OF THE MAGNESIUM-ACTIVATED ADENOSINETRIPHOSPHATASE BY W. WAYNE KIELLEYt

In the initial work (1) on the partial isolation and properties of a new magnesium-activated ATPase’ of muscle, it was observed that the enzyme preparations contained a large amount of organic phosphorus, most of which was lipide phosphorus. The relatively small amount of nucleic acid phosphorus could be removed with ribonuclease without impairing the activity of the ATPase. Attempts to separate the enzyme from the lipide material were unsuccessful. The present report is the result of continued attempts to purify the ATPase by separation of the protein and lipide components. These experiments have produced substantial evidence that the association between lipide and protein is essential for the characteristic ATPase activity.