Download MendeleyStructural insights into ortho -aminophenol oxidases: kinetic and crystallographic characterization of Sm NspF and Sg GriF.
Le Xuan, H., Rompel, A.(2026) Inorg Chem Front 13: 3786-3794
- PubMed: 41836335 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1039/d5qi02495a
- Primary Citation Related Structures:
9T62 - PubMed Abstract:
Actinobacteria-derived o -aminophenol oxidases (AOs) represent a largely unexplored subclass of type-III copper enzymes with catalytic properties distinct from tyrosinases and catechol oxidases. The determination of the first crystal structure of an AO ( Sm NspF) displays unique loop insertions and important second-sphere amino acids in vicinity of the binuclear copper center. The substrate-guiding effect of the second activity controller (His B2+1 ) influences the binding affinity for carboxyl-containing substrates in the AOs Sm NspF and Sg GriF. Thus, kinetic investigations reveal both overlapping and distinct substrate preferences for Sm NspF and Sg GriF: while both enzymes oxidize monophenols, o -aminophenols, and o -diphenols, they do so at significantly different reaction rates. Sm NspF preferentially oxidizes carboxylated substrates such as 3,4-dihydroxybenzoic acid and 3-amino-4-hydroxybenzoic acid, whereas Sg GriF exhibits higher activity toward para -methylated analogs, including 4-methylcatechol and 2-amino-4-methylphenol. Remarkably, both enzymes display enzymatic activities beyond the known AO reactivity spectrum by oxidizing 2-aminoresorcinol and o -phenylenediamine, which underlies the high versatility of the binuclear copper center. Altogether, these findings provide a structural basis for AO's enzymatic activity and broaden the known catalytic spectrum, which enables the prediction of catalytic properties in type-III copper proteins based on their amino acid sequence.
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie Josef-Holaubek Platz 2 1090 Vienna Austria annette.rompel@univie.ac.at https://www.bpc.univie.ac.at.
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