Influence of light on phosphoenol pyravate carboxylase in sorghum leaves

Abstract

Upon greening of sorghum leaves ( Sorghum vulgare Pers. cv. INRA 450) under white light illumination, phosphoenolpyruvate carboxylase activity increases. 17 times; at the same time, a new isoform of the enzyme appears. The aim of the present work has been to identify the process responsible for the appearance of this isoform. Greening. of the leaves in the presence of D 2 O did not lead to a significant increase in the buoyant density of the enzyme. On the other hand, cycloheximide was a powerful inhibitor of the rise in PEP carboxylase activity. In order to clarify these conflicting data a procedure based on the immunoprecipitation of the enzyme and its quantification by gel electrophoresis was developed in order to estimate the amount of enzyme in leaf tissue. The results clearly demonstrate that light triggers an increased synthesis of the enzyme protein during greening of sorghum leaves.