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研究了脯氨酸三肽(甘氨酰脯氨酰甘氨酸、脯氨酰甘氨酰甘氨酸和脯氨酰脯氨酰甘氨酸)质子化离子的主要产物离子的解离机理.量子化学计算表明,a2离子的环状结构在能量上比其线性结构更加稳定,三肽结构中的脯氨酸对b2离子产生a2离子的解离过程的反应势能分布有较大影响.a2离子的裂解过程中发生了离子/中性复合物介导的分子内质子迁移反应,推测质子桥连复合物为质子迁移反应的关键中间体.此中间体对应于质谱图中a2离子丢失一分子CO的碎片离子峰.密度泛函理论模拟计算验证了b2离子和a2离子的裂解反应机理.
The dissociation mechanism of the major product ions of the protonated protons of the proline tripeptides (glycylproline glycine, prolyl glycylglycine and prolylproline glycine) was investigated.Quantum chemical calculations show that a2 The ionic ring structure is energetically more stable than its linear structure, and the proline in the tripeptide structure has a greater influence on the potential distribution of the reaction energy for the dissociation of a2 ions generated by b2 ions. The cleavage of a2 ions occurred Ion / neutral complex-mediated intramolecular proton transfer reaction, suggesting proton bridging complex is the key intermediate proton migration reaction.This intermediate corresponds to the mass spectrum of a2 ions lost one molecule of CO fragment ion peak density Functional theory simulations verify the cleavage reaction mechanism of b2 ions and a2 ions.