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Neutron cryo-crystallography captures the protonation state of ferryl heme in a peroxidase
- Casadei, Cecilia M., Gumiero, Andrea, Metcalfe, Clive L., Murphy, Emma J., Basran, Jaswir, Concilio, Maria Grazia, Teixeira, Susana C. M., Schrader, Tobias E., Fielding, Alistair J., Ostermann, Andreas, Blakeley, Matthew P., Raven, Emma L., Moody, Peter C. E.
- Science 2014 v.345 no.6193 pp. 193-197
- X-ray diffraction, crystallography, cytochrome-c peroxidase, heme, histidine, iron, oxygen, peroxidase
- Peroxidase proton placement Heme enzymes catalyze a variety of biochemical oxidations through the activation of oxygen by iron. Casadei et al. used neutron crystallography to elucidate the mechanism of cytochrome c peroxidase (see the perspective by Groves and Boaz). In the highly reactive intermediate state termed compound I, the iron(IV) oxo, or ferryl, fragment was not protonated, whereas a nearby histidine residue was protonated. The sensitivity of neutron scattering to proton locations revealed these protonation states, where more common techniques, such as x-ray diffraction, have yielded more ambiguous results. Science , this issue p. 193; see also p. 142