Li Yangjie, Cavet Guy, Zare Richard N, Driver Taran
Department of Chemistry, Stanford University, Stanford, California 94305, United States.
Flatiron Bio, LLC, Palo Alto, California 94301, United States.
Anal Chem. 2024 Sep 9. doi: 10.1021/acs.analchem.4c03202.
Therapeutic peptides that are connected by disulfide bonds are often difficult to analyze by traditional tandem mass spectrometry without chemical modification. Using fragment correlation mass spectrometry, we analyzed 56 pairs of fragment ions generated from an equimolar (10 μM) mixture of three cyclic peptides, achieving sequence coverage of 86%, 100%, and 75% for octreotide, desmopressin, and the structural analogue of desmopressin, respectively. In all detected fragment ion pairs, only 20% of the fragment ions are terminal ions, with most of the measured ions only detected by fragment correlation mass spectrometry. From the peak volumes in the covariance map, we calculated branching ratios of each disulfide bond fragmentation pathway, providing a direct measurement of the probability of each fragmentation without requiring alteration of the chemical structure of the analytes.
通过二硫键连接的治疗性肽在未经化学修饰的情况下，通常难以用传统串联质谱进行分析。利用碎片相关质谱，我们分析了由三种环肽的等摩尔（10 μM）混合物产生的56对碎片离子，分别实现了奥曲肽、去氨加压素和去氨加压素结构类似物86%、100%和75%的序列覆盖率。在所有检测到的碎片离子对中，只有20%的碎片离子是末端离子，大多数测量离子仅通过碎片相关质谱检测到。根据协方差图中的峰体积，我们计算了每条二硫键断裂途径的分支比，无需改变分析物的化学结构即可直接测量每种断裂的概率。
