Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12779/6533
Title: Redox-Active Sites in Auricularia auricula-judae Dye-Decolorizing Peroxidase and Several Directed Variants: A Multifrequency EPR Study
Authors: Baratto, Maria Camilla 
Sinicropi, Adalgisa 
Linde, Dolores
Sáez-Jiménez, Verónica
Sorace, Lorenzo
Ruiz-Duenas, Francisco J.
Martinez, Angel T.
Basosi, Riccardo 
Pogni, Rebecca 
Issue Date: 2015
Project: None 
Journal: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL
Abstract: 
Peroxide-activated Auricularia auricula-judae dye-decolorizing peroxidase (DyP) forms a mixed Trp377 and Tyr337 radical, the former being responsible for oxidation of the typical DyP substrates (Linde et al. Biochem. J., 2015, 466, 253−262); however, a pure tryptophanyl radical EPR signal is detected at pH 7 (where the enzyme is inactive), in contrast with the mixed signal observed at pH for optimum activity, pH 3. On the contrary, the presence of a second tyrosine radical (at Tyr147) is deduced by a multifrequency EPR study of a variety of simple and double-directed variants (including substitution of the above and other tryptophan and tyrosine residues) at different freezing times after their activation by H2O2 (at pH 3). This points out that subsidiary long-range electron-transfer pathways enter into operation when the main pathway(s) is removed by directed mutagenesis, with catalytic efficiencies progressively decreasing. Finally, self-reduction of the Trp377 neutral radical is observed when reaction time (before freezing) is increased in the absence of reducing substrates (from 10 to 60 s). Interestingly, the tryptophanyl radical is stable in the Y147S/Y337S variant, indicating that these two tyrosine residues are involved in the self-reduction reaction.
Description: 
76253
URI: http://hdl.handle.net/20.500.12779/6533
ISSN: 1520-6106
DOI: 10.1021/acs.jpcb.5b02961
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