L-Arabinose 1-dehydrogenase (AraDH) is responsible for the first step of the non-phosphorylative L-arabinose pathway from bacteria, and catalyzes the NAD(P)⁺-dependent oxidation of L-arabinose to L-arabinonolactone. This enzyme belongs to the so-called Gfo/Idh/MocA protein superfamily, but has a very poor phylogenetic relationship with other functional members. We previously reported the crystal structures of AraDH without a ligand and in complex with NADP⁺. To clarify the underlying catalytic mechanisms in more detail, we herein elucidated the crystal structure in complex with L-arabinose and NADP⁺. In addition to the previously reported five amino acid residues (Lys91, Glu147, His153, Asp169, and Asn173), His119, Trp152, and Trp231 interacted with L-arabinose, which were not found in substrate recognition by other Gfo/Idh/MocA members. Structure-based site-directed mutagenic analyses suggested that Asn173 plays an important role in catalysis, whereas Trp152, Trp231, and His119 contribute to substrate binding. The preference of NADP⁺ over NAD⁺ was significantly subjected by a pair of Ser37 and Arg38, whose manners were similar to other Gfo/Idh/MocA members.

L-阿拉伯糖1-脱氢酶（AraDH）负责细菌中非磷酸化L-阿拉伯糖途径的第一步，并催化L-阿拉伯糖向L-阿拉伯糖基内酯的NAD（P）⁺依赖性氧化。该酶属于所谓的Gfo / Idh / MocA蛋白超家族，但与其他功能成员的系统发育关系非常差。我们先前曾报道AraDH的晶体结构没有配体，并且与NADP ^+形成复合物。为了更详细地阐明潜在的催化机理，我们在本文中阐明了与L-阿拉伯糖和NADP ⁺配合形成的晶体结构。除了先前报道的五个氨基酸残基（Lys91，Glu147，His153，Asp169和Asn173）外，His119，Trp152和Trp231还与L-阿拉伯糖相互作用，这在其他Gfo / Idh / MocA成员的底物识别中均未发现。基于结构的定点诱变分析表明，Asn173在催化中起重要作用，而Trp152，Trp231和His119有助于底物结合。一对Ser37和Arg38显着影响了NADP ⁺对NAD ⁺的偏好，其方式与其他Gfo / Idh / MocA成员相似。