4cvi

Publication Abstract from PubMed

Heme enzymes activate oxygen through formation of transient iron-oxo (ferryl) intermediates of the heme iron. A long-standing question has been the nature of the iron-oxygen bond and, in particular, the protonation state. We present neutron structures of the ferric derivative of cytochrome c peroxidase and its ferryl intermediate; these allow direct visualization of protonation states. We demonstrate that the ferryl heme is an Fe(IV)=O species and is not protonated. Comparison of the structures shows that the distal histidine becomes protonated on formation of the ferryl intermediate, which has implications for the understanding of O-O bond cleavage in heme enzymes. The structures highlight the advantages of neutron cryo-crystallography in probing reaction mechanisms and visualizing protonation states in enzyme intermediates.

Heme enzymes. Neutron cryo-crystallography captures the protonation state of ferryl heme in a peroxidase.,Casadei CM, Gumiero A, Metcalfe CL, Murphy EJ, Basran J, Concilio MG, Teixeira SC, Schrader TE, Fielding AJ, Ostermann A, Blakeley MP, Raven EL, Moody PC Science. 2014 Jul 11;345(6193):193-7. doi: 10.1126/science.1254398. Epub 2014 Jul, 10. PMID:25013070^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.