Barlow Christopher K, McFadyen W David, O'Hair Richard A J
School of Chemistry and Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria 3010, Australia.
J Am Chem Soc. 2005 Apr 27;127(16):6109-15. doi: 10.1021/ja043088f.
The collision-induced dissociation (CID) of a series of gas-phase complexes M(III)(salen)(P) [where M = Cr, Mn, Fe, and Co; P = hexapeptides YGGFLR, WGGFLR, and GGGFLR; and salen = N,N'-ethylenebis(salicylideneaminato)] has been examined with respect to the ability of the complexes to form the corresponding cationic peptide radical ions, P(+)(*), by homolytic cleavage of the metal peptide bond. This is the first example of the use of gas-phase ternary metal peptide complexes to produce the corresponding cationic peptide radical for a metal other than copper(II). The fragmentation reactions competing with radical formation are highly dependent on the metal ion used. In addition, examination of modified complexes in which the periphery of the salen was substituted allowed evaluation of electronic effects on the CID process, presumably without significant change in the geometry surrounding the metal. This substitution demonstrates that the ligand can be used to tune the dissociation chemistry to favor radical formation and suppress unwanted further fragmentation of the peptide radical that is typically observed immediately following its dissociation from the complex.
研究了一系列气相配合物[M(III)(salen)(P)]⁺[其中M = Cr、Mn、Fe和Co；P = 六肽YGGFLR、WGGFLR和GGGFLR；salen = N,N'-亚乙基双(水杨醛氨基)]的碰撞诱导解离(CID)，考察了这些配合物通过金属肽键的均裂形成相应阳离子肽自由基离子P(⁺)(*)的能力。这是使用气相三元金属肽配合物为除铜(II)以外的金属生成相应阳离子肽自由基的首个实例。与自由基形成竞争的碎片化反应高度依赖于所使用的金属离子。此外，对salen外围被取代的修饰配合物进行研究，能够评估电子效应在CID过程中的作用，推测金属周围的几何结构没有显著变化。这种取代表明，该配体可用于调节解离化学过程，以利于自由基形成，并抑制肽自由基从配合物解离后通常立即发生的不必要的进一步碎片化。
