Incorporation of Radioactive Amino Acids into the Proteins of Plant Tissue Homogenates.

It has been established (2, 12) that intact tissues of higher plants readily incorporate C14-labeled amino acids into their cellular proteins. In addition, evidence has been presented (11) that an isolated mitochondrial fraction from bean seedlings is capable of incorporating several amino acids. This incorporation into mitochondrial protein is of particular interest as it closely resembles the synthesis of simple peptides (14, 15, 16) in its dependence on the respiratory energy of adenosinetriphosphate (ATP). The ability of such an isolated cellular fraction to incorporate amino acids makes a further study of cell-free systems of interest. The sole purpose of the present investigation has been to study in some detail the incorporation of amino acids into the proteins of cell-free extracts of higher plants. The present communication reports results on the nature of the incorporation process and on the partial purification and properties of a particulate system from pea seedlings that incorporates amino acids at relatively high rates.