Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
Department of Food Science, National Taiwan Ocean University, Keelung 202, Taiwan.
Acta Crystallogr D Struct Biol. 2019 Aug 1;75(Pt 8):733-742. doi: 10.1107/S2059798319009574. Epub 2019 Jul 30.
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.
对羟基扁桃酸氧化酶（Hmo）是一种黄素单核苷酸（FMN）依赖性酶，可将扁桃酸氧化为苯甲酰甲酸。Hmo 如何进行 FMN 依赖性氧化在分子水平上仍不清楚。Hmo 及其与生理/非生理底物、产物和抑制剂复合物的晶体结构的连续快照为其底物对映选择性/混杂性、活性位点几何形状/反应性及其直接氢化物转移机制提供了依据。出乎意料地观察到一个单一的突变体 Y128F，它将双电子氧化反应扩展到四电子氧化脱羧反应。利用生物化学、动力学、稳定同位素标记和 X 射线晶体学等生化和结构方法得出了这些结论，并提供了更多的见解。
