Computational de novo design, and characterization of an A(2)B(2) diiron protein.

Diiron proteins are found throughout nature and have a diverse range of functions; proteins in this class include methane monooxygenase, ribonucleotide reductase, Delta(9)-acyl carrier protein desaturase, rubrerythrin, hemerythrin, and the ferritins. Although each of these proteins has a very different overall fold, in every case the diiron active site is situated within a four-helix bundle. Additionally, nearly all of these proteins have a conserved Glu-Xxx-Xxx-His motif on two of the four helices with the Glu and His residues ligating the iron atoms.