Kleinnijenhuis Anne J, Heck Albert J R, Duursma Marc C, Heeren Ron M A
Department of Biomolecular Mass Spectrometry, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
J Am Soc Mass Spectrom. 2005 Oct;16(10):1595-601. doi: 10.1016/j.jasms.2005.05.010.
We studied lacticin 481, a small lantibiotic with three lanthionine bridges, by electron capture dissociation (ECD) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Following electron capture, very little fragmentation was observed, but species formed by nondissociative single and multiple electron capture were abundant. Ions formed by double electron capture were subjected to sustained off resonance irradiation collision induced dissociation (SORI-CID) to determine whether stable biradicals were formed. In the SORI-CID spectra of the ions formed by double electron capture, some, but minor, H* radical loss was observed, which was not observed at all for regularly protonated ions. A small part of the ions formed by double electron capture are thus long-lived biradicals. Apart from the observed H* loss, the SORI-CID spectra of ions that captured two electrons was similar to that of regularly protonated ions and quite different from the SORI-CID spectra of radical ions formed by single electron capture. This implies that recombination of the two radical sites is the dominant process in biradical lacticin 481 ions, at least on the time scale of our SORI-CID experiments.
我们在傅里叶变换离子回旋共振（FTICR）质谱仪中通过电子捕获解离（ECD）研究了乳酸链球菌素481，一种具有三个羊毛硫氨酸桥的小分子羊毛硫抗生素。电子捕获后，观察到的碎片化很少，但非解离性单电子和多电子捕获形成的物种很丰富。对双电子捕获形成的离子进行持续非共振辐照碰撞诱导解离（SORI-CID），以确定是否形成了稳定的双自由基。在双电子捕获形成的离子的SORI-CID光谱中，观察到了一些但较少的H自由基损失，而对于常规质子化离子则完全没有观察到这种情况。因此，双电子捕获形成的一小部分离子是长寿命双自由基。除了观察到H损失外，捕获两个电子的离子的SORI-CID光谱与常规质子化离子的光谱相似，与单电子捕获形成的自由基离子的SORI-CID光谱有很大不同。这意味着两个自由基位点的重组是双自由基乳酸链球菌素481离子中的主要过程，至少在我们的SORI-CID实验的时间尺度上是这样。
