Final answer:
The final reaction in heme synthesis is catalyzed by ferrochelatase, which inserts iron into the protoporphyrin IX ring. This process is part of a tightly regulated pathway that balances heme and globin production.
Step-by-step explanation:
The enzyme that catalyzes the final reaction in heme synthesis is called ferrochelatase (or heme synthase). This enzyme catalyzes the insertion of iron into the protoporphyrin IX ring to form heme. Heme synthesis is tightly regulated, with the synthesis of 5-aminolevulinic acid (ALA) by ALA synthase being a key regulatory step. Heme itself acts as a feedback inhibitor of this enzyme, demonstrating an example of negative feedback regulation within the cell. Inhibitors like succinylacetone and N-methyl mesoporphyrin IX can interfere with heme synthesis at different steps. Moreover, heme synthesis is also intertwined with the regulation of globin protein synthesis, ensuring that the rates of heme and globin production are synchronized to produce functional hemoglobin.