Effects of transition metal ion coordination on the collision-induced dissociation of polyalanines.
Effects of transition metal ion coordination on the collision-induced dissociation of polyalanines.
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DOI：
10.1002/jms.1992
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
Heather M. Watson;J. Vincent;C. Cassady
中科院分区：
文献类型：
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作者：
Heather M. Watson;J. Vincent;C. Cassady
电喷雾电离后，在高容量四极离子阱中分析过渡金属-聚丙氨酸复合物。聚丙氨酸没有极性氨基酸侧链来配位金属离子，因此可以探索金属离子与肽主链相互作用的影响。由与第一行过渡金属 Cr(III)、Fe(II)、Fe(III)、Co(II)、Ni(II)、Cu(I) 和 Cu(II) 盐混合的肽产生的正模式质谱产生单电荷和双电荷金属化离子。这些前体离子经历碰撞诱导解离 (CID)，几乎完全产生金属化的 N 端产物离子，其类型和相对丰度取决于过渡金属的特性。例如，Cr(III) 阳离子化肽产生的 CID 光谱很复杂，并且有一些中性损失，而 Fe(III) 阳离子化肽则解离产生强烈的非金属化产物。添加 Cu(II) 显示出最有希望用于测序。从单电荷和双电荷 Cu-七丙氨酸离子 [M + Cu - H](+) 和 [M + Cu](2+) 的 CID 获得的光谱是互补的，并且共同提供每个残基的裂解，并且没有中性损失。 （这与七丙氨酸的 [M + H](+) 形成对比，其中 CID 不提供骨架离子来对前三个残基进行测序。）过渡金属阳离子化通过 CID 产生丰富的金属化 a-离子，这与主要产生 b-和 y-离子的质子化肽不同。金属化 a 离子的重要性很有趣，因为它们并不总是由 b 离子形成。金属化（Met = 金属）a- 和 b- 离子的串联质谱表明 [b(n) + Met - H](2+) 失去 CO 形成 [a(n) + Met - H](2+)，模拟质子化结构。相反，[a(n) + Met - H](2+) 消除氨基酸残基形成 [a(n-1) + Met - H](2+)，这可能有助于测序。
Transition metal-polyalanine complexes were analyzed in a high-capacity quadrupole ion trap after electrospray ionization. Polyalanines have no polar amino acid side chains to coordinate metal ions, thus allowing the effects metal ion interaction with the peptide backbone to be explored. Positive mode mass spectra produced from peptides mixed with salts of the first row transition metals Cr(III), Fe(II), Fe(III), Co(II), Ni(II), Cu(I), and Cu(II) yield singly and doubly charged metallated ions. These precursor ions undergo collision-induced dissociation (CID) to give almost exclusively metallated N-terminal product ions whose types and relative abundances depend on the identity of the transition metal. For example, Cr(III)-cationized peptides yield CID spectra that are complex and have several neutral losses, whereas Fe(III)-cationized peptides dissociate to give intense non-metallated products. The addition of Cu(II) shows the most promise for sequencing. Spectra obtained from the CID of singly and doubly charged Cu-heptaalanine ions, [M + Cu - H](+) and [M + Cu](2+) , are complimentary and together provide cleavage at every residue and no neutral losses. (This contrasts with [M + H](+) of heptaalanine, where CID does not provide backbone ions to sequence the first three residues.) Transition metal cationization produces abundant metallated a-ions by CID, unlike protonated peptides that produce primarily b- and y-ions. The prominence of metallated a-ions is interesting because they do not always form from b-ions. Tandem mass spectrometry on metallated (Met = metal) a- and b-ions indicate that [b(n) + Met - H](2+) lose CO to form [a(n) + Met - H](2+), mimicking protonated structures. In contrast, [a(n) + Met - H](2+) eliminate an amino acid residue to form [a(n-1) + Met - H](2+), which may be useful in sequencing.