What is the function of PEP carboxylase in C4 plants?

PEP carboxylase plays a crucial role in the photosynthetic process of C4 plants by initiating the fixation of carbon dioxide. This enzyme catalyzes the reaction between phosphoenolpyruvate (PEP) and carbon dioxide, leading to the production of a four-carbon compound, oxaloacetate, which is an important step in the C4 photosynthetic pathway.

In contrast to C3 plants, which directly fix carbon dioxide into a three-carbon compound through the enzyme RuBisCO, C4 plants use PEP carboxylase to efficiently capture carbon dioxide even under low concentrations or hot, dry conditions, thus minimizing photorespiration. This adaptation allows C4 plants to maintain a higher rate of photosynthesis and thrive in environments where C3 plants might struggle.

Understanding PEP carboxylase's function highlights its importance in the overall efficiency of carbon fixation in C4 plants, illustrating how specialized adaptations can lead to enhanced survival in various environmental conditions.