Models of fragmentations induced by electron attachment to protonated peptides
Models of fragmentations induced by electron attachment to protonated peptides
复制标题
DOI：
10.1255/ejms.665
复制
发表时间：
2004-01-01
影响因子：
1.3
通讯作者：
Uggerud, E
中科院分区：
文献类型：
--
作者：
Bakken, V;Helgaker, T;Uggerud, E
在从HF/STO-3G到CCSD（T）/aug-cc-pVQZ的多个理论水平上，我们对六个势能面（NH_4 ~+，NH_4 ~+，[CH3CONHCH3]H+，[CH3CONHCH3]H-，[HCONHCH 2CONH 2]H+和[HCONHCH 2CONH 2]H-）。与此同时，从头算直接动力学计算已经进行，跟踪几百个反应轨迹，揭示电子捕获解离机制的细节。模型计算表明，双峰模式的可能性，其中一些自由基，重组后形成，几乎直接在一皮秒内解离，其余的自由基受到完整的能量再分配与随后的解离发生在微秒的时间尺度。这两个过程都产生c和z骨架片段，由肽链的N-C-α键裂解产生。
Invoking a number of theoretical levels ranging from HF/STO-3G to CCSD(T)/aug-cc-pVQZ, we have made a detailed survey of six potential energy surfaces (NH4+, NH4., [CH3CONHCH3]H+, [CH3CONHCH3]H-., [HCONHCH2CONH2]H+ and [HCONHCH2CONH2]H-.). In conjunction with this, ab inito direct dynamics calculations have been conducted, tracing out several hundred reaction trajectories to reveal details of the electron-capture dissociation mechanism. The model calculations suggest the possibility of a bimodal pattern where some of the radicals, formed upon recombination, dissociate almost directly within one picosecond, the remaining radicals being subject to complete energy redistribution with a subsequent dissociation occurring at the microsecond timescale. Both processes give rise to c and z backbone fragments, resulting from cleavage of N-C-alpha bonds of the peptide chain.