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Updated: Aug 6, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
The 2.0 A structure of human ferrochelatase, the terminal enzyme of heme biosynthesis
1Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229, USA.
Abstract:
Human ferrochelatase (E.C. 4.99.1.1) is a homodimeric (86 kDa) mitochondrial membrane-associated enzyme that catalyzes the insertion of ferrous iron into protoporphyrin to form heme. We have determined the 2.0 A structure from the single wavelength iron anomalous scattering signal. The enzyme contains two NO-sensitive and uniquely coordinated [2Fe-2S] clusters. Its membrane association is mediated in part by a 12-residue hydrophobic lip that also forms the entrance to the active site pocket. The positioning of highly conserved residues in the active site in conjunction with previous biochemical studies support a catalytic model that may have significance in explaining the enzymatic defects that lead to the human inherited disease erythropoietic protoporphyria.
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