Question

In phase 1 oxidations catalyzed by cytochrome P450, what is the role of the iron atom in the active site?

a. It remains unchanged during the oxidation process.
b. It forms a complex with the substrate.
c. It transfers oxygen to the substrate.
d. It is reduced to Fe(III) to restore the enzyme.

Answer 1

The role of the iron atom in the active site of cytochrome P450 in phase 1 oxidations is to transfer oxygen to the substrate.

Step-by-step explanation:

c. It transfers oxygen to the substrate. In phase 1 oxidations catalyzed by cytochrome P450, the iron atom in the heme group of the enzyme's active site plays a crucial role in transferring molecular oxygen (O₂) to the substrate. Cytochrome P450 enzymes are heme-containing proteins, and the iron ion in the heme group undergoes a cycle of oxidation and reduction during the catalytic process. Molecular oxygen binds to the iron in the ferrous (Fe²⁺) state, forming a complex. The iron then transfers one oxygen atom to the substrate, while the other oxygen atom is reduced to water. This transfer of oxygen is a key step in the oxidation reactions mediated by cytochrome P450 enzymes.