Fragmentation mechanism of product ions from protonated proline-containing tripeptides in electrospray ionization mass spectrometry  

作　　者：YOU ZhuShuang WEN YongJun JIANG KeZhi PAN YuanJiang 

机构地区：[1]Department of Chemistry,Zhejiang University,Hangzhou 310027,China [2]Chengdu Capgemini Biomedical Technology Company,Ltd.,Chengdu 611330,China [3]Key Laboratory of Organosilicon Chemistry and Material Technology,Hangzhou Normal University,Hangzhou 310012,China

出　　处：《Chinese Science Bulletin》2012年第17期2051-2061,共11页

基　　金：supported by China National Funds for Distinguished Young scientists(21025207);the National Natural Science Foundation of China(20975092);the Zhejiang Provincial Natural Science Foundation of China(Y4100020)

摘　　要：The dissociation chemistry of primary fragment ions from the protonated proline-containing tripeptides glycylprolylglycine,prolylglycylglycine,and prolylprolylglycine was investigated by electrospray ionization multi-stage mass spectrometry.Calcula-tions showed the a 2 ions generated from b 2 ions were cyclic,which is energetically more favorable than the linear form.The prolyl residue in the structure affected the energy hypersurface of the dissociation reaction from the b 2 ion to the a 2 ion.In the fragmen-tation of a 2 ions,the iminium-imine complex corresponding to loss of CO from the a 2 ion was suggested to be an ion-neutral com-plex (INC).The a 1 ion was generated from direct separation of this INC,and the internal iminium ion,which was absent in PGG,was generated from another INC that was formed from the first INC via proton-bridged complex-mediated intramolecular proton transfer.Although these intermediates are unstable,their existence is supported by experiments and density functional theory calculations.The dissociation chemistry of primary fragment ions from the protonated proline-containing tripeptides glycylprolylglycine, prolylglycylglycine, and prolylprolylglycine was investigated by electrospray ionization multi-stage mass spectrometry. Calculations showed the a2 ions generated from b2 ions were cyclic, which is energetically more favorable than the linear form. The prolyl residue in the structure affected the energy hypersurface of the dissociation reaction from the b2 ion to the a2 ion. In the fragmentation of a2 ions, the iminium-imine complex corresponding to loss of CO from the a2 ion was suggested to be an ion-neutral com- plex （INC）. The al ion was generated from direct separation of this INC, and the internal iminium ion, which was absent in PGG, was generated from another INC that was formed from the first INC via proton-bridged complex-mediated intramolecular proton transfer. Although these intermediates are unstable, their existence is supported by experiments and density functional theory calculations.

关 键 词：分子内质子转移 质谱裂解机理 碎片离子 电喷雾 脯氨酸 三肽 产品 密度泛函理论 

分 类 号：O629.71[理学—有机化学] O657.63[理学—化学]