Halophilic enzymes need high salt concentrations for activity and stability and are considered a promising source for biotechnological applications. The model study for haloadaptation has been proteins from the Halobacteria class of Archaea, where common structural characteristics have been found. However, the effect of salt on enzyme function and conformational dynamics has been much less explored. Here we report the structural and kinetic characteristics of glucose-6-phosphate dehydrogenase from Haloferax volcanii (HvG6PDH) belonging to the short-chain dehydrogenases/reductases (SDR) superfamily. The enzyme was expressed in Escherichia coli and successfully solubilized and refolded from inclusion bodies. The enzyme is active in the presence of several salts, though the maximum activity is achieved in the presence of KCl, mainly by an increment in the k_cat value, that correlates with a diminution of its flexibility according to molecular dynamics simulations. The high K_M for glucose-6-phosphate and its promiscuous activity for glucose restrict the use of HvG6PDH as an auxiliary enzyme for the determination of halophilic glucokinase activity. Phylogenetic analysis indicates that SDR-G6PDH enzymes are exclusively present in Halobacteria, with HvG6PDH being the only enzyme characterized. Homology modeling and molecular dynamics simulations of HvG6PDH identified a conserved NLTX₂H motif involved in glucose-6-phosphate interaction at high salt concentrations, whose residues could be crucial for substrate specificity. Structural differences in its conformational dynamics, potentially related to the haloadaptation strategy, were also determined.

嗜盐酶的活性和稳定性需要高盐浓度，被认为是生物技术应用的有前途的来源。Haloadaptation 的模型研究是来自盐细菌古细菌类，其中发现了共同的结构特征。然而，盐对酶功能和构象动力学的影响却很少被探索。在这里，我们报告了葡萄糖-6-磷酸脱氢酶的结构和动力学特征。火龙果 (高压G6PDH) 属于短链脱氢酶/还原酶 (SDR) 超家族。该酶表达于大肠杆菌并成功地从包涵体中溶解和重新折叠。该酶在几种盐的存在下是有活性的，尽管在 KCl 存在下达到最大活性，主要是通过增加克_猫值，这与根据分子动力学模拟其灵活性的降低相关。高钾_米 6-磷酸葡萄糖及其对葡萄糖的混杂活性限制了使用 高压G6PDH 作为测定嗜盐葡萄糖激酶活性的辅助酶。系统发育分析表明 SDR-G6PDH 酶仅存在于盐细菌， 和 高压G6PDH是唯一被表征的酶。同源建模和分子动力学模拟高压G6PDH 鉴定了在高盐浓度下参与葡萄糖-6-磷酸相互作用的保守 NLTX ₂ H 基序，其残基对于底物特异性至关重要。还确定了其构象动力学的结构差异，可能与 haloadaptation 策略有关。