Nnamchi, Chukwudi I, Parkin, Gary, Efimov, Igor et al. (9 more authors) (2016) Structural and spectroscopic characterisation of a heme peroxidase from sorghum. Journal of Biological Inorganic Chemistry. pp. 1-8. ISSN 0949-8257
Abstract
A cationic class III peroxidase from Sorghum bicolor was purified to homogeneity. The enzyme contains a high-spin heme, as evidenced by UV-visible spectroscopy and EPR. Steady state oxidation of guaiacol was demonstrated and the enzyme was shown to have higher activity in the presence of calcium ions. A Fe(III)/Fe(II) reduction potential of -266 mV vs NHE was determined. Stopped-flow experiments with H2O2 showed formation of a typical peroxidase Compound I species, which converts to Compound II in the presence of calcium. A crystal structure of the enzyme is reported, the first for a sorghum peroxidase. The structure reveals an active site that is analogous to those for other class I heme peroxidase, and a substrate binding site (assigned as arising from binding of indole-3-acetic acid) at the γ-heme edge. Metal binding sites are observed in the structure on the distal (assigned as a Na(+) ion) and proximal (assigned as a Ca(2+)) sides of the heme, which is consistent with the Ca(2+)-dependence of the steady state and pre-steady state kinetics. It is probably the case that the structural integrity (and, thus, the catalytic activity) of the sorghum enzyme is dependent on metal ion incorporation at these positions.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2015, The Authors. This content is made available by the publisher under a Creative Commons Attribution Licence. This means that a user may copy, distribute and display the resource providing that they give credit. Users must adhere to the terms of the licence. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Depositing User: | Pure (York) |
Date Deposited: | 02 Mar 2016 11:23 |
Last Modified: | 16 Oct 2024 12:48 |
Published Version: | https://doi.org/10.1007/s00775-015-1313-z |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1007/s00775-015-1313-z |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:95790 |
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