In biochemistry, non-heme iron proteins describe families of enzymes that utilize iron at the active site but lack heme cofactors. Iron-sulfur proteins, including those that are enzymes, are not included in this definition. By tradition, non-heme iron enzymes refers to those involved in oxygen activation, [1] such as those described below.
Some non-heme iron proteins contain one Fe at their active sites, others have pairs of Fe centers:
- Many mono-Fe proteins are alpha-ketoglutarate-dependent hydroxylases. Major examples are the lipoxygenases, isopenicillin N synthase, protocatechuate 3,4-dioxygenase, deacetoxycephalosporin-C synthase, [2] and aromatic amino acid hydroxylases. [3] [4]
- Major diiron enzymes include hemerythrin, some ribonucleotide reductases, [5] some methane monooxygenases, [6]
Oxygenation of hemerythrin, a non-heme diiron protein.
