Abstract Bacitracin is a mixture of antimicrobial peptides. Although the structures of bacitracins have been fully studied, the structure elucidation of the oxidation products of bacitracin has rarely been reported. In the present work, the bacitracin was treated by hydrogen peroxide solution to form bacitracin sulfonic acids (SO3H) directly, and the structures of bacitracin-SO3Hs were studied by high performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry (HPLC-QTOF-MS/MS). It was demonstrated that the components of bacitracin, such as bacitracin A, B, and C could be site-specifically transformed to the corresponding oxidized product containing the SO3H group. The structure characterization of the oxidized products was elucidated based on the accurate molecular mass and the product ions obtained by MS/MS. Some new kinds of bacitracin J-SO3H, vinyl-bacitracin A-SO3H, bacitracin Y-SO3H and deamino-bacitracin Y-SO3H were identified. Furthermore, we also investigated the novel fragmentation behavior of the oxidized products. This is the first report to propose a neutral loss mechanism of SO3 that explains the characteristic ions of the vinyl-bacitracin A-SO3H and bacitracin Y-SO3H. Based on the structure analysis of the oxidation products of bacitracin, three transformation routes of bacitracin-SO3H generated from bacitracin were hypothesized and systematically summarized for the first time.

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基于高效液相色谱-四极杆飞行时间-串联质谱的新型杆菌肽磺酸结构解析

摘要 杆菌肽是抗菌肽的混合物。尽管已经对杆菌肽的结构进行了充分的研究，但对杆菌肽氧化产物的结构解析却鲜有报道。本工作采用双氧水处理杆菌肽直接生成杆菌肽磺酸（SO3H），采用高效液相色谱-四极杆飞行时间-串联质谱（HPLC-QTOF）对杆菌肽-SO3Hs的结构进行了研究。 -MS/MS）。结果表明，杆菌肽的组分，如杆菌肽 A、B 和 C，可以位点特异性地转化为相应的含有 SO3H 基团的氧化产物。基于精确的分子质量和 MS/MS 获得的产物离子阐明了氧化产物的结构表征。鉴定了一些新的杆菌肽J-SO3H、乙烯基杆菌肽A-SO3H、杆菌肽Y-SO3H和脱氨基杆菌肽Y-SO3H。此外，我们还研究了氧化产物的新型裂解行为。这是首次提出 SO3 中性损失机制的报告，该机制解释了乙烯基杆菌肽 A-SO3H 和杆菌肽 Y-SO3H 的特征离子。基于杆菌肽氧化产物的结构分析，首次假设并系统总结了杆菌肽生成杆菌肽-SO3H的3条转化路线。这是首次提出 SO3 中性损失机制的报告，该机制解释了乙烯基杆菌肽 A-SO3H 和杆菌肽 Y-SO3H 的特征离子。基于杆菌肽氧化产物的结构分析，首次假设并系统总结了杆菌肽生成杆菌肽-SO3H的3条转化路线。这是首次提出 SO3 中性损失机制的报告，该机制解释了乙烯基杆菌肽 A-SO3H 和杆菌肽 Y-SO3H 的特征离子。基于杆菌肽氧化产物的结构分析，首次假设并系统总结了杆菌肽生成杆菌肽-SO3H的3条转化路线。