Isocitrate dehydrogenase is a catabolic enzyme that acts during the third step of the tricarboxylic acid cycle. The hypothetical protein ST2166 from the archaeon Sulfolobus tokodaii was isolated and crystallized. It shares high primary structure homology with prokaryotic NADP⁺-dependent IDHs, suggesting that these enzymes share a common enzymatic mechanism. The crystal structure of ST2166 was determined at 2.0 Å resolution in the apo form, and then the structure of the crystal soaked with NADP⁺ was also determined at 2.4 Å resolution, which contained NADP⁺ bound at the putative active site. Comparisons between the structures of apo and NADP⁺-bound forms and NADP-IDHs from other prokaryotes suggest that prokaryotic NADP-IDHs recognize their cofactors using conserved Lys335, Tyr336, and Arg386 in ST2166 at the opening cleft before the domain closure.

中文翻译：

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Apo和NADP +结合形式的Sulfolobus tokodaii菌株7的假定的异柠檬酸脱氢酶的晶体结构。

异柠檬酸脱氢酶是一种分解代谢酶，在三羧酸循环的第三步中起作用。分离自古细菌Sulfolobus tokodaii的假定蛋白ST2166并进行结晶。它与原核NADP ⁺依赖的IDH具有很高的一级结构同源性，表明这些酶具有共同的酶促机制。以apo形式以2.0分辨率确定ST2166的晶体结构，然后以2.4分辨率确定以NADP ⁺浸透的晶体结构，其中包含在假定的活性位点结合的NADP ⁺。载脂蛋白和NADP ⁺结构的比较结合形式和其他原核生物的NADP-IDHs表明，原核NADP-IDHs在结构闭合前的开放裂隙中使用ST2166中保守的Lys335，Tyr336和Arg386来识别其辅因子。