Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, Quartier Agora, Allée du six Aout 11, B-4000, Liege, Belgium.
Commissariat à l'Energie Atomique, DRF/SIMOPRO, 91191, Gif sur Yvette, France.
J Am Soc Mass Spectrom. 2018 Oct;29(10):1995-2002. doi: 10.1007/s13361-018-2022-y. Epub 2018 Jul 9.
Disulfide connectivity in peptides bearing at least two intramolecular disulfide bonds is highly important for the structure and the biological activity of the peptides. In that context, analytical strategies allowing a characterization of the cysteine pairing are of prime interest for chemists, biochemists, and biologists. For that purpose, this study evaluates the potential of MALDI in-source decay (ISD) for characterizing cysteine pairs through the systematic analysis of identical peptides bearing two disulfide bonds, but not the same cysteine connectivity. Three different matrices have been tested in positive and/or in negative mode (1,5-DAN, 2-AB and 2-AA). As MALDI-ISD is known to partially reduce disulfide bonds, the data analysis of this study rests firstly on the deconvolution of the isotope pattern of the parent ions. Moreover, data analysis is also based on the formed fragment ions and their signal intensities. Results from MS/MS-experiments (MALDI-ISD-MS/MS) constitute the last reference for data interpretation. Owing to the combined use of different ISD-promoting matrices, cysteine connectivity identification could be performed on the considered peptides. Graphical Abstract ᅟ.
二硫键连接在至少含有两个分子内二硫键的肽中对于肽的结构和生物活性非常重要。在这种情况下，允许对半胱氨酸配对进行特征描述的分析策略对于化学家、生物化学家以及生物学家来说具有重要意义。为此，本研究通过系统分析具有两个二硫键但不同半胱氨酸连接的相同肽，评估 MALDI 源内裂解 (ISD) 对鉴定半胱氨酸对的潜在应用。三种不同的基质已在正、负模式下进行了测试 (1,5-DAN、2-AB 和 2-AA)。由于 MALDI-ISD 已知会部分还原二硫键，因此本研究的数据分析首先依赖于对母离子同位素模式的解卷积。此外，数据分析还基于形成的片段离子及其信号强度。来自 MS/MS 实验 (MALDI-ISD-MS/MS) 的结果构成了数据解释的最后参考。由于使用了不同的 ISD 促进基质，因此可以对半胱氨酸连接性进行识别。
