The effects of chromium(III) coordination on the dissociation of acidic peptides.
The effects of chromium(III) coordination on the dissociation of acidic peptides.
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铬(III)配位对酸性肽解离的影响。
DOI：
10.1002/jms.1374
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Cassady,CarolynJ
中科院分区：
文献类型：
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作者：
Pu,Dan;Vincent,JohnB;Cassady,CarolynJ
在配备电喷雾电离(ESI)的傅里叶变换离子回旋共振(FT-ICR)质谱仪上，用持续非共振辐照碰撞诱导解离(SORI-CID)方法研究了铬(III)与合成酸性多肽形成的络合物。对中性多肽和含有一个、两个和多个酸性残基的多肽进行了研究。所有多肽均形成[M+Cr−2H]+。在[M+Cr−2H]+的CID谱中发现了三个值得注意的特征。第一，[M+Cr−2H]+比[M+H]+产生的碎片离子少。原因可能是铬(III)与羧酸盐或羰基之间的多重配位阻碍了碎片离子的产生，因为在多肽内键断裂后，继续将多段多肽与铬(III)结合。第二个特征是[M+Cr−2H]+和[YN+Cr−H]+中CO的损失。提出了一种涉及铬(III)与羧酸基配位的机理，以使CO的消除合理化。第三个特征是铬(III)保留在所有的碎片离子中，表明金属离子与多肽有很强的结合。随着肽链长度和酸性残基数目的增加，形成了络合物[M+2Cr−5H]+。较长的多肽与铬(III)有更多的配位位置和更多的构象灵活性。此外，不含羧酸基的−-OCH3生成[M+CrOCH2H]+表明，铬(III)可以与多肽骨架上的位置配位，尽管丰度较低。在负值模式下，只有含有4个或4个以上羧酸基团的多肽才有[M+Cr−4H]−。这与去质子化的羧酸基参与了铬(III)的配位以及铬在气相离子中以3+状态存在是一致的。版权所有©2008 John Wiley&Sons，Ltd.
The complexes formed between chromium(III) and synthetic acidic peptides were studied by sustained off‐resonance irradiation collision‐induced dissociation (SORI‐CID) in a Fourier transform ion‐cyclotron resonance (FT‐ICR) mass spectrometer equipped with electrospray ionization (ESI). Neutral peptides and peptides containing one, two, and multiple acidic residues were studied. Formation of [M + Cr − 2H]+occurred for all peptides. Three noteworthy features were found in the CID spectra of [M + Cr − 2H]+. The first is that fewer fragment ions were produced from [M + Cr − 2H]+than from [M + H]+. The reason may be that multiple coordination between chromium(III) and carboxylate or carbonyl groups hinders the production of fragment ions by continuing to bind pieces of the peptide to chromium(III) after cleavage of bonds within the peptide. The second feature is loss of CO from [M + Cr − 2H]+and [yn+ Cr − H]+. A mechanism involving coordination of chromium(III) with carboxylate groups is proposed to rationalize elimination of CO. The third feature is that chromium(III) is retained in all fragment ions, indicating strong binding of the metal ion to the peptides. The complex [M + 2Cr − 5H]+is formed as the peptide chain length and number of acidic residues increases. Longer peptides have more sites to coordinate with chromium(III) and more conformational flexibility. In addition, formation of [M + Cr − 2H]+from AGGAAAA‐OCH3, which has no carboxylic acid groups, suggests that chromium(III) can coordinate with sites on the peptide backbone, albeit in low abundance. In the negative mode, [M + Cr − 4H]−was only found for peptides containing four or more carboxylic acid groups. This is consistent with deprotonated carboxylic acid groups being involved in chromium(III) coordination and with chromium existing in the 3 + state in the gas‐phase ions. Copyright © 2008 John Wiley & Sons, Ltd.