STRONG-INTERACTIONS OF ANIONIC PEPTIDES AND ALKALINE-EARTH METAL-IONS - METAL-ION-BOUND PEPTIDES IN THE GAS-PHASE
STRONG-INTERACTIONS OF ANIONIC PEPTIDES AND ALKALINE-EARTH METAL-IONS - METAL-ION-BOUND PEPTIDES IN THE GAS-PHASE
复制标题
DOI：
10.1021/ja00049a056
复制
发表时间：
1992-11-04
影响因子：
15
通讯作者：
GROSS, ML
中科院分区：
文献类型：
--
作者：
HU, PF;GROSS, ML
含有中性侧链氨基酸的三肽在快原子轰击下与碱土金属离子相互作用形成[tripept+Met2+-~(3 H+)]-组成的气相阴离子络合物。金属离子与去质子化的C-端羧酸基和两个酰胺氮结合。由于C-末端和中心氨基酸被金属离子紧密结合，它们不容易在串联质谱仪中被碰撞激活分解。相反，显著的碎裂发生在N末端的氨基酸位置，这是最不紧密结合的。离子是通过从N-末端消除亚胺和亚胺加CO而形成的(产物分别被指定为x2+H和y2)。该复合体的其他主要碎裂包括脱氢和氨分子的损失。具有功能化侧链的多肽，如丝氨酸、苏氨酸和苯丙氨酸，当它们与金属离子结合并受到碰撞活化时，很容易失去侧链。其他碎裂通道在很大程度上被抑制，表明直接的金属离子侧链相互作用。根据同位素标记多肽的结果和MS/MS/MS实验的结果，提出了裂解机理。
Tripeptides comprising amino acids with neutral side chains interact with alkaline earth metal ions to form gas-phase anionic complexes of the composition [tripept + Met2+ - 3H+]- under fast atom bombardment. The metal ion binds to the deprotonated C-terminal carboxylate group and to the two amide nitrogens. Because the C-terminal and the central amino acid are tightly bound by the metal ion, they are not vulnerable to collisionally activated decompositions in a tandem mass spectrometer. Instead, the significant fragmentations occur at the N-terminal amino acid site, which is the least tightly bonded. Ions are formed by elimination of an imine and the imine plus CO from the N-terminus (productions are assigned as x2 + H and y2, respectively). Other major fragmentations of this complex include dehydrogenation and loss of an ammonia molecule. Peptides with functionalized side chains, such as those of serine, threonine, and phenylalanine, lose the side chains readily when they are bound to metal ions and submitted to collisional activation. Other fragmentation channels are largely suppressed, indicating direct metal ion-side chain interaction. Fragmentation mechanisms are proposed on the basis of results with isotopically labeled peptides and from MS/MS/MS experiments.