For 10 points, name this element important for many enzyme-catalyzed redox reactions, which is coordinated to a porphyrin ring in heme.
In bacteria, siderophores are used to bind this substance and transport it into the cell, and most bacteria which rely on its oxidation for energy are obligately acidophilic. Â In humans, the major regulator of this substance's homeostasis is hepcidin, which inhibits both its release from macrophages and its absorption in the gut. Â When intracellular levels of this (*) ion are low, cytosolic aconitase binds and stabilizes mRNA to promote translation of transferrin receptors. Â Excessive absorption of this metal can lead to hemachromatosis. Â Along with copper, this metal forms the catalytic center of cytochrome oxidase, while it is found complexed to sulfur in many proteins of the electron transport chain. Â For 10 points, name this element important for many enzyme-catalyzed redox reactions, which is coordinated to a porphyrin ring in heme.
In bacteria, siderophores are used to bind this substance and transport it into the cell, and most bacteria which rely on its oxidation for energy are obligately acidophilic.
iron [accept Fe or Fe2+ or Fe3+]