Cell-free, protein-synthesizing system of photosynthetic and heterotrophic Rhodospirillum rubrum.

An active in vitro protein-synthesizing system has been developed from Rhodospirillum rubrum grown under either photosynthetic or heterotrophic conditions. A protease activity has been found in both of these systems, and this activity can be readily inactivated by treating the cells with KCl and phenylmethyl sulfonylfluoride. The difference in protein-synthesizing activity between the photosynthetic and the heterotrophic systems has been tested in regard to the requirement of various chemicals and the response to protein synthesis inhibitors or various chemical compounds. It has been concluded that only minor differences in protein-synthesizing activity exist between these two systems.