Human liver pyruvate kinase (hLPYK) converts phosphoenolpyruvate to pyruvate in the final step of glycolysis. hLPYK is allosterically activated by fructose‐1,6‐bisphosphate (Fru‐1,6‐BP). The allosteric site, as defined by previous structural studies, is located in domain C between the phosphate‐binding loop (residues 444–449) and the allosteric loop (residues 527–533). In this study, the X‐ray crystal structures of four hLPYK variants were solved to make structural correlations with existing functional data. The variants are D499N, W527H, Δ529/S531G (called GGG here) and S531E. The results revealed a conformational toggle between the open and closed positions of the allosteric loop. In the absence of Fru‐1,6‐BP the open position is stabilized, in part, by a cation–π bond between Trp527 and Arg538′ (from an adjacent monomer). In the S531E variant glutamate binds in place of the 6′‐phosphate of Fru‐1,6‐BP in the allosteric site, leading to partial allosteric activation. Finally, the structure of the D499N mutant does not provide structural evidence for the previously observed allosteric activation of the D499N variant.

中文翻译：

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活化剂结合后人肝丙酮酸激酶的变构位点的变化包括亚单位间阳离子-π键的断裂。

在糖酵解的最后步骤中，人肝丙酮酸激酶（hLPYK）将磷酸烯醇丙酮酸转化为丙酮酸。hLPYK被果糖-1,6-双磷酸酯（Fru-1,6-BP）变构激活。如先前的结构研究所定义，变构位点位于磷酸结合环（残基444-449）和变构环（残基527-533）之间的C域中。在这项研究中，解决了四个hLPYK变体的X射线晶体结构，使其与现有功能数据具有结构相关性。变体是D499N，W527H，Δ529/ S531G（在此称为GGG）和S531E。结果揭示了变构环的打开和关闭位置之间的构象转换。在没有Fru-1,6-BP的情况下，打开位置部分由Trp527和Arg538'之间的阳离子-π键（来自相邻单体）稳定。在S531E变体中，谷氨酸替代变构位点中Fru-1,6-BP的6'-磷酸，导致部分变构活化。最后，D499N突变体的结构没有为先前观察到的D499N变体的变构活化提供结构证据。