The heme group is characterized by its iron (Fe) ion core, which can exist in different oxidation states, most commonly Fe(II) and Fe(III). The iron ion is coordinated to four nitrogen atoms within the porphyrin ring. This configuration provides a versatile platform for binding other molecules, enabling the heme group to participate in various catalytic processes. The porphyrin ring itself is a large, planar, and aromatic structure, contributing to the stability and reactivity of the heme group.
