Solution state structures of human pancreatic amylin and pramlintide
Solution state structures of human pancreatic amylin and pramlintide
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DOI：
10.1093/protein/gzp029
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发表时间：
2009-08-01
影响因子：
2.4
通讯作者：
Andersen, Niels H.
中科院分区：
文献类型：
--
作者：
Cort, John R.;Liu, Zhihong;Andersen, Niels H.
我们已经采用普兰林肽（prAM）作为替代品的人上午在CD和NMR研究的构象偏好的N-末端部分的结构中的介质，不提供长寿命的单体解决方案的人上午由于其快速转化为类β-聚合物状态。可以在有利于螺旋形成的条件下进行hAM和prAM的直接比较。基于CD和NMR研究：（i）Cys（2）-Cys（7）环构象具有短跨度的螺旋（Ala（5）-Cys（7））;（ii）该螺旋进一步传播到序列中的程度取决于介质;在水性氟醇介质中观察到从Ala（5）到Ser（20）的螺旋（末端从His（18）开始磨损）;（iii）在12+体积%中HFIP，hAM的淀粉样蛋白生成区域形成第二螺旋结构域（Phe（23）-Ser（29））;（iv）hAM的两个螺旋区域不具有任何特定的几何关系，因为它们通过具有不同构象的柔性环连接，和（v）尽管末端C-末端对于生物活性是必需的，发现它是广泛随机化的，构象异构体相互转化的速率比在肽序列的其余部分中观察到的速率快得多。已推导出hAM的1-22序列片段的两个NMR衍生结构。这项工作也有助于说明改进的方法，核磁共振表征的螺旋。在水性HFIP中观察到的NOE强度的详细定量分析揭示了常见胰淀素螺旋的C-末端部分的替代构象，该区域已知参与导致淀粉样蛋白生成的生物识别现象。尽管SNN序列看起来是一个灵活的环，但化学位移（以及螺旋结构化后诱导的变化）表明，在部分螺旋形成时，环和hAM的淀粉样蛋白生成片段之间存在一些相互作用。
We have employed pramlintide (prAM) as a surrogate for hAM in CD and NMR studies of the conformational preferences of the N-terminal portion of the structure in media which do not provide long-lived monomeric solutions of hAM due to its rapid conversion to preamyloid beta aggregate states. Direct comparison of hAM and prAM could be made under helix-formation-favoring conditions. On the basis of CD and NMR studies: (i) the Cys(2)-Cys(7) loop conformation has a short-span of helix (Ala(5)-Cys(7)); (ii) the extent to which this helix propagates further into the sequence is medium-dependent; a helix from Ala(5) through Ser(20) (with end fraying from His(18) onward) is observed in aqueous fluoroalcohol media; (iii) in 12+ vol.% HFIP, the amyloidogenic region of hAM forms a second helical domain (Phe(23)-Ser(29)); (iv) the two helical regions of hAM do not have any specific geometric relationship as they are connected by a flexible loop that takes different conformations and (v) although the extreme C-terminus is essential for bioactivity, it is found to be extensively randomized with conformer interconversions occurring at a much faster rate than that is observed in the remainder of the peptide sequence. Two NMR-derived structures of the 1-22 sequence fragment of hAM have been derived. The work also serves to illustrate improved methods for the NMR characterization of helices. A detailed quantitative analysis of the NOE intensities observed in aqueous HFIP revealed alternative conformations in the C-terminal portion of the common amylin helix, a region that is known to be involved in the biorecognition phenomena leading to amyloidogenesis. Even though the SNN sequence appears to be a flexible loop, the chemical shifts (and changes induced upon helix structuring) suggest some interactions between the loop and the amyloidogenic segment of hAM that occur on partial helix formation.