The enzyme that catalyses carbon dioxide fixation in C₄ plants is

The enzyme that catalyzes carbon dioxide fixation in C₄ plants is PEP carboxylase.
PEP carboxylase, which is located in the mesophyll cells, is an essential enzyme in C₄ plants.
In hot and dry environments, carbon dioxide concentrations inside the leaf fall when the plant closes or partially closes its stomata to reduce water loss from the leaves.