The active site of nitric oxide reductase from Paracoccus denitrificans contains heme and non-heme iron and is evolutionarily related to heme-copper oxidases. The CO and NO dynamics in the active site were investigated using ultrafast transient absorption spectroscopy. We find that, upon photodissociation from the active site heme, 20% of the CO rebinds in 170 ps, suggesting that not all the CO transiently binds to the non-heme iron. The remaining 80% does not rebind within 4 ns and likely migrates out of the active site without transient binding to the non-heme iron. Rebinding of NO to ferrous heme takes place in ~ 13 ps. Our results reveal that heme-ligand recombination in this enzyme is considerably faster than in heme-copper oxidases and are consistent with a more confined configuration of the active site. © 2008 Elsevier B.V. All rights reserved.
Kapetanaki, S. M., Field, S. J., Hughes, R. J. L., Watmough, N. J., Liebl, U., & Vos, M. H. (2008). Ultrafast ligand binding dynamics in the active site of native bacterial nitric oxide reductase. Biochimica et Biophysica Acta - Bioenergetics, 1777(7–8), 919–924. https://doi.org/10.1016/j.bbabio.2008.03.012