The enzyme PEP carboxylase A) can fix CO₂ even at relatively low CO₂ concentrations. B) catalyzes the synthesis of RuBP. C) catalyzes the synthesis of 3PG. D) is found in the chloroplasts of bundle sheath cells. E) couples the synthesis of ATP to the diffusion of protons.

Question

Quizplus · Accepted Answer

PEP carboxylase is an enzyme found in C4 plants that catalyzes the addition of CO2 to PEP (phosphoenolpyruvate), forming oxaloacetate, which can then be converted to malate or aspartate for transport to bundle sheath cells. Unlike Rubisco (the enzyme responsible for carbon fixation in C3 plants), PEP carboxylase has a higher affinity for CO2, allowing it to fix CO2 even at low concentrations.

The Enzyme PEP Carboxylase