Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.
Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.
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DOI：
10.1371/journal.pone.0056467
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Alexandrescu AT
中科院分区：
文献类型：
--
作者：
Alexandrescu AT
胰淀素是一种内分泌激素，在晚期2型糖尿病患者的淀粉样斑块中积累。淀粉样蛋白斑块与胰腺β细胞的破坏有关，胰腺β细胞合成胰淀素和胰岛素。为了更好地表征淀粉样蛋白原纤维中胰淀素的二级结构，我们分配了在95%DMSO中未折叠状态的NMR光谱，并使用淬灭的氢-氘交换技术来观察原纤维中的酰胺质子溶剂保护。在该技术中，将部分交换的原纤维溶解在95%DMSO中，并从DMSO变性的单体确定关于原纤维中酰胺质子占据的信息。在pH 7.6和37°C下的氢交换寿命在非结构化N-末端的0.55小时至两个β-链中的酰胺质子的600小时之间变化，所述两个β-链沿着原纤维的长度在胰淀素单体之间形成分子间氢键沿着。基于保护数据，我们得出结论，残基A8-H18和I26-Y37构成胰淀素原纤维中的两条β链。β链内的保护存在变化，特别是对于链β1，其中仅残基F15-H18受到强保护。保护的差异似乎是由于在原丝结构中两层C2-淀粉酶相关的β-发夹的堆积对主链动力学的限制，其中链β1位于表面，β2位于内部。
Amylin is an endocrine hormone that accumulates in amyloid plaques in patients with advanced type 2 diabetes. The amyloid plaques have been implicated in the destruction of pancreatic β-cells, which synthesize amylin and insulin. To better characterize the secondary structure of amylin in amyloid fibrils we assigned the NMR spectrum of the unfolded state in 95% DMSO and used a quenched hydrogen-deuterium exchange technique to look at amide proton solvent protection in the fibrils. In this technique, partially exchanged fibrils are dissolved in 95% DMSO and information about amide proton occupancy in the fibrils is determined from DMSO-denatured monomers. Hydrogen exchange lifetimes at pH 7.6 and 37°C vary between ∼5 h for the unstructured N-terminus to 600 h for amide protons in the two β-strands that form inter-molecular hydrogen bonds between amylin monomers along the length of the fibril. Based on the protection data we conclude that residues A8-H18 and I26-Y37 comprise the two β-strands in amylin fibrils. There is variation in protection within the β-strands, particularly for strand β1 where only residues F15-H18 are strongly protected. Differences in protection appear to be due to restrictions on backbone dynamics imposed by the packing of two-layers of C2-symmetry-related β-hairpins in the protofilament structure, with strand β1 positioned on the surface and β2 in the interior.
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影响因子：
4.8
作者：
Jha, Suman;Patil, Sharadrao M.;Alexandrescu, Andrei T.
通讯作者：
Alexandrescu, Andrei T.
影响因子：
5.6
作者：
Guardino KM;Sheftic SR;Slattery RE;Alexandrescu AT
通讯作者：
Alexandrescu AT
DOI：
10.1016/s1359-0278(97)00024-2
发表时间：
1997-01-01
期刊：
FOLDING & DESIGN
影响因子：
--
作者：
Bahar, I;Atilgan, AR;Erman, B
通讯作者：
Erman, B
影响因子：
2.9
作者：
Luca, Sorin;Yau, Wai-Ming;Tycko, Robert
通讯作者：
Tycko, Robert
影响因子：
4.8
作者：
Damo, Steven M.;Phillips, Aaron H.;Wemmer, David E.
通讯作者：
Wemmer, David E.