The presence and role of phosphopyruvate carboxylase in etiolated coleoptiles of Avena sativa

Phosphopyruvate carboxylase and malic enzyme were detected in etiolated coleoptiles of Avena sativa, and it was concluded that the incorporation of 14C-labeled bicarbonate into aspartate and glutamate involved the activity of the former enzyme. IAA stimulated the fixation of labeled bicarbonate, and the incorporation of labeled leucine into protein was increased in the presence of carbon dioxide. It is suggested that the carbon dioxide stimulated growth of Avena coleoptiles is due to an increased rate of protein synthesis which is dependent on carbon dioxide fixation.