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Biochemical and structural explorations of α‐hydroxyacid oxidases reveal a four‐electron oxidative decarboxylation reaction
Author(s) -
Yeh Hsien-Wei,
Lin Kuan-Hung,
Lyu Syue-Yi,
Li Yi-Shan,
Huang Chun-Man,
Wang Yung-Lin,
Shih Hao-Wei,
Hsu Ning-Shian,
Wu Chang-Jer,
Li Tsung-Lin
Publication year - 2019
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798319009574
Subject(s) - decarboxylation , oxidative decarboxylation , chemistry , flavin group , flavin mononucleotide , electron transfer , stereochemistry , electron transport chain , oxidative phosphorylation , active site , enzyme , oxidoreductase , substrate (aquarium) , photochemistry , biochemistry , catalysis , biology , ecology
p ‐Hydroxymandelate oxidase (Hmo) is a flavin mononucleotide (FMN)‐dependent enzyme that oxidizes mandelate to benzoylformate. How the FMN‐dependent oxidation is executed by Hmo remains unclear at the molecular level. A continuum of snapshots from crystal structures of Hmo and its mutants in complex with physiological/nonphysiological substrates, products and inhibitors provides a rationale for its substrate enantioselectivity/promiscuity, its active‐site geometry/reactivity and its direct hydride‐transfer mechanism. A single mutant, Y128F, that extends the two‐electron oxidation reaction to a four‐electron oxidative decarboxylation reaction was unexpectedly observed. Biochemical and structural approaches, including biochemistry, kinetics, stable isotope labeling and X‐ray crystallography, were exploited to reach these conclusions and provide additional insights.