Enzyme-mediated reaction?

What is the name of the enzyme in this enzyme-mediated reaction?

Enzymatic reactions follow the classical “lock-and-key” model, where the free enzyme E binds to its substrate S to form the enzyme–substrate complex (C1), which is then catalyzed into the enzyme–product complex (C2) from which the free enzyme and product are released: S + E ↔ C1 ↔ C2 → P + E.