Relationship between Protein Synthesis in Tuber Discs and the Protein Synthetic Activity of a Cell-Free Preparation.

A cell-free system which synthesizes protein was isolated from ;aged' discs of Jerusalem artichoke tubers. The synthetic activity was largely associated with the fraction containing mitochondria. Preparations from freshly cut tissue were virtually inactive but increasingly active preparations were obtained from discs ;aged' for progressively longer periods; those from 24 hour discs showing maximum activity. The characteristics of this change are reminiscent of the rate of development of invertase, a marker for protein synthesis in the intact disc. Extensive investigations showed that bacterial contamination was not a significant factor in the synthetic activity.