Spectral properties of bacterial nitric-oxide reductase: Resolution of pH-dependent forms of the active site heme b3

Field, Sarah J., Prior, Louise, Roldán, M. Dolores, Cheesman, Myles, Thomson, Andrew J., Spiro, Stephen, Butt, Julea ORCID: https://orcid.org/0000-0002-9624-5226, Watmough, Nick and Richardson, David ORCID: https://orcid.org/0000-0002-6847-1832 (2002) Spectral properties of bacterial nitric-oxide reductase: Resolution of pH-dependent forms of the active site heme b3. The Journal of Biological Chemistry, 277 (23). pp. 20146-20150. ISSN 1083-351X

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Abstract

Bacterial nitric-oxide reductase catalyzes the two electron reduction of nitric oxide to nitrous oxide. In the oxidized form the active site non-heme FeB and high spin heme b 3 are µ-oxo bridged. The hemeb 3 has a ligand-to-metal charge transfer band centered at 595 nm, which is insensitive to pH over the range of 6.0–8.5. Partial reduction of nitric-oxide reductase yields a three electron-reduced state where only the hemeb 3 remains oxidized. This results in a shift of the heme b 3 charge transfer band ?max to longer wavelengths. At pH 6.0 the charge transfer band ?max is 605 nm, whereas at pH 8.5 it is 635 nm. At pH 6.5 and 7.5 the nitric-oxide reductase ferric hemeb 3 population is a mixture of both 605- and 635-nm forms. Magnetic circular dichroism spectroscopy suggests that at all pH values examined the proximal ligand to the ferric hemeb 3 in the three electron-reduced form is histidine. At pH 8.5 the distal ligand is hydroxide, whereas at pH 6.0, when the enzyme is most active, it is water.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Groups > Organisms and the Environment Faculty of Science > Research Groups > Chemistry of Light and Energy Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Energy Materials Laboratory
Depositing User:	Rachel Smith
Date Deposited:	15 Feb 2011 16:50
Last Modified:	27 Oct 2023 00:41
URI:	https://ueaeprints.uea.ac.uk/id/eprint/21419
DOI:	10.1074/jbc.M112202200

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