PDF(Pubmed)
Abstract：
We characterise a reversible bacterial zinc-containing benzyl alcohol dehydrogenase (BaDH) accepting either NAD+ or NADP+ as a redox cofactor. Remarkably, its redox cofactor specificity is pH-dependent with the phosphorylated cofactors favored at lower and the dephospho-forms at higher pH. BaDH also shows different steady-state kinetic behavior with the two cofactor forms. From a structural model, the pH-dependent shift may affect the charge of a histidine in the 2\'-phosphate-binding pocket of the redox cofactor binding site. The enzyme is phylogenetically affiliated to a new subbranch of the Zn-containing alcohol dehydrogenases, which share this conserved residue. BaDH appears to have some specificity for its substrate, but also turns over many substituted benzyl alcohol and benzaldehyde variants, as well as compounds containing a conjugated C=C double bond with the aldehyde carbonyl group. However, compounds with an sp3-hybridised C next to the alcohol/aldehyde group are not or only weakly turned over. The enzyme appears to contain a Zn in its catalytic site and a mixture of Zn and Fe in its structural metal-binding site. Moreover, we demonstrate the use of BaDH in an enzyme cascade reaction with an acid-reducing tungsten enzyme to reduce benzoate to benzyl alcohol. KEY POINTS: •Zn-containing BaDH has activity with either NAD + or NADP+ at different pH optima. •BaDH converts a broad range of substrates. •BaDH is used in a cascade reaction for the reduction of benzoate to benzyl alcohol.
摘要：
我们表征了可逆的细菌含锌苯甲醇脱氢酶（BaDH），该酶接受NAD或NADP作为氧化还原辅因子。值得注意的是,它的氧化还原辅因子特异性是pH依赖性的，磷酸化辅因子在较低的情况下更受欢迎，而去磷形式在较高的pH下更受欢迎。BaDH还显示了两种辅因子形式的不同稳态动力学行为。从结构模型来看，pH依赖性变化可能会影响氧化还原辅因子结合位点的2'-磷酸结合袋中组氨酸的电荷。该酶在系统发育上隶属于含锌醇脱氢酶的新分支，分享这些保守的残留物。BaDH似乎对其底物有一些特异性，而且还包括许多取代的苯甲醇和苯甲醛变体，以及含有与醛羰基共轭的C=C双键的化合物。然而,醇/醛基团旁边具有sp3杂化C的化合物不会或仅微弱地翻转。该酶似乎在其催化位点中含有Zn，在其结构金属结合位点中含有Zn和Fe的混合物。此外，我们证明了BaDH在与酸还原钨酶的酶级联反应中将苯甲酸酯还原为苯甲醇的用途。关键词:•含Zn的BaDH在不同的最佳pH下具有NAD+或NADP+的活性。•BaDH转化宽范围的底物。•BaDH用于将苯甲酸酯还原为苯甲醇的级联反应。
