Lasso peptides are a diverse class of ribosomally synthesized and post-translationally modified peptides (RiPPs). Their proteolytic and thermal stability alongside their growing potential as therapeutics has increased attention to these antimicrobial peptides. With the advent of genome mining, the discovery of RiPPs allows for the accurate prediction of putatively encoded structures, however, MSⁿ experiments only provide partial sequence confirmation, therefore 2D NMR experiments are necessary for characterisation. Multiple MS/MS techniques were applied to two structurally characterized lasso peptides, huascopeptin and leepeptin, and one uncharacterized lasso peptide, citrulassin C, which was not isolable in sufficient quantity for NMR analysis. We have shown that MS² can be used to elucidate the full amino acid sequences previously predicted with genome mining for this compound class. HCD was able to open the macrocycles and fragment the newly opened linear peptides, confirming the complete amino acid sequences of the characterised lasso peptides. In addition, to determine if this technique could be applied at the earliest stages of the isolation process, we targeted a lasso peptide found by genome mining, citrulassin C, and were able to fully elucidate the amino acid sequence using only MS² from a semi-crude extract of Streptomyces huasconensis HST28^T.

套索肽是核糖体合成的和翻译后修饰的肽（RiPPs）的不同种类。它们的蛋白水解和热稳定性以及作为治疗剂的潜力不断增长，越来越引起人们对这些抗菌肽的关注。随着基因组挖掘的出现，RiPPs的发现可以准确预测推定编码的结构，但是MS ⁿ实验仅提供部分序列确认，因此2D NMR实验对于表征是必要的。多种MS / MS技术应用于两种具有结构特征的套索肽huascopeptin和leepeptin，以及一种未表征的套索肽citlulassin C，其分离量不足以进行NMR分析。我们已经证明MS ²可用于阐明先前通过基因组挖掘对该化合物类别预测的完整氨基酸序列。HCD能够打开大环并片段化新打开的线性肽，从而确认了特征化的套索肽的完整氨基酸序列。此外，为了确定该技术是否可以在分离过程的最早阶段应用，我们针对了通过基因组挖掘发现的套索肽瓜氨酸酶C，并且仅使用半序列MS ²就能完全阐明了氨基酸序列。华链霉菌HST28 ^T的粗提物。