Adenosine triphosphatase in isolated bacterial cell membranes.

Among the recognized morphological features of cells, the esternal membrane is one of the most poorly understood in terms of both structure and function, especially with regard to its participation in transport processes. In recent years, the chemical and enzymatic composition of isolated cell membranes from a few species of bacterial organisms have received the attention of a number of investigators (1) after the demonstration by Weibull (2) that cell membranes could be prepared by osmotic lysis of bacterial protoplasts. The recent finding (3) in this laboratory that protoplasts could be prepared from Streptococcus jaecalis (ATCC ~9790) by treatment with lysozyme, has now made it possible to isolate the cell membrane from this organism and to initiate a study of its chemical and enzymatic constitution. Our first efforts were directed to the enzyme adenosine triphosphatase, because in previous studies with the intact cells and protoplasts, the presence of this enzyme in the cell membrane was proposed in order to account for the changes in permeability that occur during glycolysis and subsequent to cessation of glycolysis (3, 4). In the present paper, evidence will be presented that the isolated membranes of S. jaecalis contain adenosine triphosphatase, and some properties of this enzyme will be described. In addition, procedures for the preparation of the cell membranes from S. jaecalis will be described, inasmuch as these structures have not been previously isolated from this organism.