Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute , University of Bonn , An der Immenburg 4 , D-53121 Bonn , Germany.
Clemens Schöpf Institute of Organic Chemistry and Biochemistry , Darmstadt University of Technology , Alarich-Weiss-Strasse 4 , D-64287 Darmstadt , Germany.
Anal Chem. 2018 Mar 6;90(5):3321-3327. doi: 10.1021/acs.analchem.7b04854. Epub 2018 Feb 8.
Peptides and proteins carrying high numbers of cysteines can adopt various 3D structures depending on their disulfide connectivities. The unambiguous verification of such conformational isomers with more than two disulfide bonds is extremely challenging, and experimental strategies for their unequivocal structural analysis are largely lacking. We synthesized all 15 possible isomers of the 22mer conopeptide μ-PIIIA and applied 2D NMR spectroscopy and MS/MS for the elucidation of its structure. This study provides intriguing insights in how the disulfide connectivity alters the global fold of a toxin. We also show that analysis procedures involving comprehensive combinations of conventional methods are required for the unambiguous assignment of disulfides in cysteine-rich peptides and proteins and that standard compounds are crucially needed for the structural analysis of such complex molecules.
带有大量半胱氨酸的肽和蛋白质可以根据其二硫键连接方式采用各种 3D 结构。具有两个以上二硫键的这种构象异构体的明确验证极具挑战性，并且用于其明确结构分析的实验策略在很大程度上缺乏。我们合成了 22 肽 μ-PIIIA 的全部 15 种可能异构体，并应用 2D NMR 光谱和 MS/MS 来阐明其结构。这项研究深入了解了二硫键连接如何改变毒素的整体构象。我们还表明，需要涉及常规方法的全面组合的分析程序来明确鉴定富含半胱氨酸的肽和蛋白质中的二硫键，并且对于此类复杂分子的结构分析，标准化合物是至关重要的。
