Hemin

Hemin, also known as ferriprotoporphyrin IX chloride, is the ferric (iron(III)) form of heme, the porphyrin-based prosthetic group found in many proteins. In hemin, the central iron is six-coordinate, with four nitrogens from the porphyrin ring and a sixth ligand, commonly a chloride ion in the isolated compound; within proteins, that sixth coordination site is typically occupied by a histidine residue or a water molecule.

Chemically, hemin is a dark, relatively insoluble solid that tends to aggregate in water. It is more soluble in organic solvents or in solutions containing detergents or alkaline conditions. The molecule is derived from heme by oxidation, and in solution it can exist in various aggregation forms, which can influence its spectral and reactivity properties.

Natural occurrence and applications: Hemin is the ferric component of heme and is encountered as a breakdown product of heme-containing proteins. In research, it serves as a convenient source of ferric heme for reconstituting or studying heme-containing enzymes and proteins, as well as for spectroscopic and enzymatic assays that require ferric heme.

Medical use: Hemin preparations are used medically to treat acute porphyrias. Intravenous hemin (often referred to as Panhematin or hemin for injection) provides exogenous heme to downregulate hepatic ALA synthase, reducing the overproduction of porphyrin precursors. Administration is done under medical supervision due to potential adverse effects and required dosing.

Safety and handling: Hemin is sensitive to light and can cause injection-site reactions and other adverse effects when used clinically. Proper handling and medical guidance are essential for therapeutic use.