Previously, we have reported that ATP accelerates the folding and unfolding of Escherichia coli glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), which is a glycolytic enzyme utilizing NAD⁺ as a cofactor. Because ATP and NAD⁺ share the ADP moiety, we hypothesized that NAD⁺ also accelerates the folding of GAPDH and that the common structural motif between ATP and NAD⁺ is responsible for the chaperone activity. After confirming that NAD⁺ indeed accelerates the folding of GAPDH, we examined the chaperone activity of the structural fragments of NAD⁺ (ADP, AMP, adenosine, and nicotinamide monophosphate). Our finding showed that ADP and AMP significantly speed up the folding of GAPDH, while adenosine and nicotinamide monophosphate do not. ADP and AMP also dramatically speed up the unfolding of GAPDH by selectively stabilizing a transition state in which GAPDH has a partially unfolded conformation. Similar to the previously reported effect of ATP on the equilibrium unfolding of GAPDH, a partially unfolded intermediate also accumulates in the presence of ADP and AMP. Based on the effect of the structural fragments of NAD⁺ on the folding of GAPDH, we identified that AMP is the structural determinant of the chaperone activity of ATP and NAD⁺. Also, we propose a plausible model to explain how NAD⁺ accelerates the folding of GAPDH through a stepwise development of molecular interactions with the protein.

中文翻译：

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伴侣蛋白伴侣在蛋白质折叠中的作用。

以前，我们已经报道过ATP会加速大肠杆菌3-磷酸​​甘油醛-磷酸脱氢酶（GAPDH）的折叠和展开，GAPDH是一种利用NAD ⁺作为辅因子的糖酵解酶。因为ATP和NAD ⁺共享ADP部分，所以我们假设NAD ⁺也会加速GAPDH的折叠，并且ATP和NAD ⁺之间的共同结构基序负责分子伴侣的活性。在确认NAD ⁺确实加速了GAPDH折叠后，我们检查了NAD ⁺结构片段的分子伴侣活性。（ADP，AMP，腺苷和烟酰胺单磷酸酯）。我们的发现表明，ADP和AMP显着加快了GAPDH的折叠速度，而腺苷和烟酰胺单磷酸却没有。ADP和AMP还可以通过选择性地稳定过渡状态（其中GAPDH具有部分展开的构象）来极大地加快GAPDH的展开。类似于先前报道的ATP对GAPDH平衡展开的作用，在ADP和AMP的存在下，部分展开的中间体也会积聚。基于NAD ⁺的结构片段对GAPDH折叠的影响，我们确定AMP是ATP和NAD ⁺分子伴侣活性的结构决定因素。另外，我们提出了一个合理的模型来解释NAD ⁺ 通过逐步发展与蛋白质的分子相互作用来加速GAPDH的折叠。