Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) serves as an important control element in the regulation of photosynthetic carbon metabolism in C4 and CAM plants. This is the first enzyme of the pathway, and PEPC enzymes are encoded by a small multigenic family. Several isoforms of PEPC have been characterised in maize, sorghum and sugarcane. These isoforms are involved in several functions such as the initial fixation of atmospheric CO2 (= C4 PEPC) and anaplerotic functions associated with nitrogen assimilation or amino acid biosynthesis (Lepiniec et al. 1994).
