采用液相色谱-四级杆飞行时间质谱(LC-QTOF-MS)联用技术,研究了系统素及其相似多肽的质谱裂解机理和色谱保留规律,探讨了它们的碰撞诱导解离规律.结果表明,系统素准分子离子一般带有2-5个电荷;在低碰撞能条件下,多肽母离子发生碰撞诱导解离,产生b型和Y型碎片离子;烟草系统素I最强母离子[M+3H]3+的最优碰撞能为22 V;番茄系统素、土豆系统素Ⅰ、土豆系统素Ⅱ、辣椒系统素和龙葵系统素的最强母离子均为[M+4H]4-,最优碰撞能均为18 V;在最优碰撞能作用下,系统素的碎片离子信息丰富,特征碎片离子峰的强度最大,适合对系统素的分析;样品中三氟乙酸的含量对系统素及相似多肽在反相色谱柱上的保留影响明显.%Fragmentation mechanism and chromatographic retention of systemins and systemin-like peptides were investigated by liquid chromatography online coupled to electrospray ionization-quadru-pole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). The characteristic fragment ions of respective systemins, the rule of collision-induced dissociation (CID) as well as the chromatographic retention of these peptides on reversed phase LC were examined. The two to five fold protonated systemin ions were observed, and informative b-and y-type fragment ions were generated. The opti-mal collision energy of [M+3H]3+ was found to be 22 V for tobacco systemin I (TobSys I ), and [M+4H]4+ was 18 V for respective tomato systemin (TomSys), potato systemin I (PotSys I ), potato systemin Ⅱ (PotSys Ⅱ ), pepper systemin (PepSys) and nightshade systemin (NishSys), respectively. Under the optimal experimental conditions, abundant unique fragment ions of the systemins were generated, which can be used for the accurate qualitative and quantitative analysis of systemins. In addition, the results of chromatographic retention showed that the retention time of systemins was obviously influenced by trifluoroacetic acid (TFA) content in the sample solution.
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