Can ferric-oxyl excited states explain elongated iron-oxygen bonds in heme peroxidase catalytic intermediates?

Journal Article · Thu Jan 01 00:00:00 EST 2026 · Nature Communications

DOI:https://doi.org/10.1038/s41467-026-69192-8· OSTI ID:3029178

Williams, Lewis J; Kamps, Jos J A G; Brânzanic, Adrian M V; Lehene, Maria; Lundgren, Kristoffer J M; Ryde, Ulf; Chatterjee, Kuntal; Doyle, Margaret D; Simon, Philipp S; Makita, Hiroki; Thompson, Amy J; Brewster, Aaron S; Zhou, Tiankun; Lučić, Marina; Wilson, Michael T; Aller, Pierre; Sanchez-Weatherby, Juan; Gee, Leland; Dehe, Sebastian; Mous, Sandra ; Yano, Junko; Yachandra, Vittal K; Hough, Michael A; Orville, Allen M; Kern, Jan F; Silaghi-Dumitrescu, Radu L; Worrall, Jonathan A R

The use of X-ray structures to determine and interpret the ferryl iron-oxygen bond order in molecular oxygen-activating heme enzymes has, in the past, been controversial. This has mainly stemmed from the susceptibility of ferryl species to X-ray-induced electronic state changes. In this work we establishe using time-resolved serial femtosecond X-ray crystallography (tr-SFX) on a dye-decolourising peroxidase that the ferryl intermediate species (Compounds I and II) captured following in situ mixing of microcrystals with H2O2 have single, rather than the double bond character expected. X-ray emission validated tr-SFX data with quantum refinement, time-dependent-DFT calculations and QM/MM geometry optimizations together support the concept that the single iron-oxygen bond character is not an indication of ferryl reduction or a protonated form (FeIV-OH) but is instead attributed to the existence of accessible excited states possessing ferric-oxyl (FeIII–O•–) character. Such states offer insight into the nature of ferryl heme.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Department of Energy; USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 3029178
• Journal Information: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 17
• Country of Publication: United States
• Language: English