Schinschel C, Simon H
Institute of Organic Chemistry, Technische Universität München, Garching, Germany.
Bioorg Med Chem. 1994 Jun;2(6):483-91. doi: 10.1016/0968-0896(94)80018-9.
Resting cells of Proteus mirabilis effectively dehydrogenate aldonates and aldarates to the corresponding 2-oxocarboxylates (Figure 2). The prerequisite is an (R)-configured alpha-carbon atom next to the carboxylate group. The oxidation reagent is dimethylsulfoxide and the electron mediator is anthraquinone-2,6-disulfonate (Figure 1). The reactions mostly proceed quantitatively in concentrations up to 0.5 M. The two enzymes necessary for the dehydrogenation, (2R)-hydroxycarboxylate viologen oxidoreductase and dimethylsulfoxide reductase, are present in P. mirabilis in high activities. Nine aldonates have been dehydrogenated to 2-glyculosonates (2-oxoaldonates) and two aldarates to alpha-oxo aldarates. As shown with lactobionate and 6-phospho-D-gluconate, derivatives of aldonates can be dehydrogenated too. The apparent Km values of the substrates are often < 1 mM. The products were isolated as sodium or potassium salts with yields between 65 and 98% and characterized. D-xylo-Hex-2-ulosonate obtained from D-gulonate was converted to D-ascorbic acid.
奇异变形杆菌的静息细胞能有效地将醛糖酸和醛糖二酸脱氢生成相应的2-氧代羧酸盐（图2）。前提是羧酸盐基团旁边有一个（R）构型的α碳原子。氧化试剂是二甲基亚砜，电子介质是蒽醌-2,6-二磺酸盐（图1）。这些反应在浓度高达0.5 M时大多能定量进行。脱氢所需的两种酶，即（2R）-羟基羧酸盐紫精氧化还原酶和二甲基亚砜还原酶，在奇异变形杆菌中具有高活性。九种醛糖酸已被脱氢生成2-糖醛酸（2-氧代醛糖酸），两种醛糖二酸被脱氢生成α-氧代醛糖二酸。如乳糖酸和6-磷酸-D-葡萄糖酸所示，醛糖酸的衍生物也能被脱氢。底物的表观Km值通常<1 mM。产物以钠盐或钾盐形式分离，产率在65%至98%之间，并进行了表征。从D-古洛糖酸得到的D-木酮糖-2-酮酸被转化为L-抗坏血酸。
