In general, eukaryotic glucose-6-phosphate dehydrogenases (G6PDHs) are structurally stabilized by NADP+. Here we show by spectrofluorometric analysis, thermal and urea denaturation, and trypsin proteolysis, that a different mechanism stabilizes the enzyme from Pseudomonas aeruginosa (PaG6PDH) (EC 1.1.1.363). The spectrofluorometric analysis of the emission of 8-anilino-1-naphthalenesulfonic acid (ANS) indicates that this stabilization is the result of a structural change in the enzyme caused by G6P. The similarity between the Kd values determined for the PaG6PDH-G6P complex (78.0 ± 7.9 μM) and the K0.5 values determined for G6P (57.9 ± 2.5 and 104.5 ± 9.3 μM in the NADP+- and NAD+-dependent reactions, respectively) suggests that the structural changes are the result of G6P binding to the active site of PaG6PDH. Modeling of PaG6PDH indicated the residues that potentially bind the ligand. These results and a phylogenetic analysis of the amino acid sequences of forty-four G6PDHs, suggest that the stabilization observed for PaG6PDH could be a characteristic that distinguishes this and other G6PDHs that use NAD+ and NADP+ from those that use NADP+ only or preferentially, such as those found in eukaryotes. This characteristic could be related to the metabolic roles these enzymes play in the organisms to which they belong.

中文翻译：

---

铜绿假单胞菌的葡萄糖6-磷酸脱氢酶的底物提供结构稳定性。

通常，NADP +在结构上稳定了真核葡萄糖6-磷酸脱氢酶（G6PDHs）。在这里，我们通过荧光光谱分析，热和尿素变性以及胰蛋白酶水解表明，一种不同的机制可以稳定铜绿假单胞菌（PaG6PDH）（EC 1.1.1.363）中的酶。对8-苯胺基-1-萘磺酸（ANS）的发射光谱进行荧光分析表明，这种稳定作用是G6P引起的酶结构变化的结果。为PaG6PDH-G6P复合物确定的Kd值（78.0±7.9μM）与为G6P确定的K0.5值（NADP +-和NAD +依赖性反应分别为57.9±2.5和104.5±9.3μM）之间的相似性表明结构变化是G6P与PaG6PDH活性位点结合的结果。PaG6PDH的建模表明可能与配体结合的残基。这些结果以及对44个G6PDH氨基酸序列的系统发育分析表明，观察到的PaG6PDH的稳定性可能是一个特征，使该特征和其他使用NAD +和NADP +的G6PDH与仅使用或优先使用NADP +的G6PDH区别开来，例如在真核生物中发现的那些。该特征可能与这些酶在它们所属的生物中发挥的代谢作用有关。例如在真核生物中发现的那些。该特征可能与这些酶在它们所属的生物中发挥的代谢作用有关。例如在真核生物中发现的那些。该特征可能与这些酶在它们所属的生物中发挥的代谢作用有关。