Laskin Julia
Pacific Northwest National Laboratory, Fundamental Science Directorate, Richland, Washington 99352, USA.
J Phys Chem A. 2006 Jul 13;110(27):8554-62. doi: 10.1021/jp057229r.
Dissociation of singly protonated leucine enkephalin (YGGFL) was studied using surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially configured for studying ion activation by collisions with surfaces. The energetics and dynamics of seven primary dissociation channels were deduced from modeling the time- and energy-resolved fragmentation efficiency curves for different fragment ions using an RRKM-based approach developed in our laboratory. The following threshold energies and activation entropies were determined in this study: E(0) = 1.20 eV and DeltaS++ = -20 eu(1) (MH(+)-->b(5)); E(0) = 1.14 eV and DeltaS++ = -14.7 eu (MH(+)-->b(4)); E(0) = 1.42 eV and DeltaS++ = -2.5 eu (MH(+)-->b(3)); E(0) = 1.30 eV and DeltaS++ = -4.1 eu (MH(+)-->a(4)); E(0) = 1.37 eV and DeltaS++ = -5.2 eu (MH(+)-->y ions); E(0) = 1.50 eV and DeltaS++ = 1.6 eu (MH(+)-->internal fragments); E(0) = 1.62 eV and DeltaS++ = 5.2 eu (MH(+)-->F). Comparison with Arrhenius activation energies reported in the literature demonstrated for the first time the reversal of the order of activation energies as compared to threshold energies for dissociation.
在一台专门配置用于研究离子与表面碰撞激活的傅里叶变换离子回旋共振质谱仪（FT-ICR MS）中，使用表面诱导解离（SID）研究了单质子化亮氨酸脑啡肽（YGGFL）的解离。利用我们实验室开发的基于RRKM的方法，通过对不同碎片离子的时间分辨和能量分辨碎裂效率曲线进行建模，推导了七个主要解离通道的能量学和动力学。本研究确定了以下阈值能量和活化熵：E(0) = 1.20 eV且ΔS++ = -20 eu(1) （MH(+)→b(5)）；E(0) = 1.14 eV且ΔS++ = -14.7 eu （MH(+)→b(4)）；E(0) = 1.42 eV且ΔS++ = -2.5 eu （MH(+)→b(3)）；E(0) = 1.30 eV且ΔS++ = -4.1 eu （MH(+)→a(4)）；E(0) = 1.37 eV且ΔS++ = -5.2 eu （MH(+)→y离子）；E(0) = 1.50 eV且ΔS++ = 1.6 eu （MH(+)→内部碎片）；E(0) = 1.62 eV且ΔS++ = 5.2 eu （MH(+)→F）。与文献中报道的阿累尼乌斯活化能进行比较，首次证明了解离活化能顺序与阈值能量顺序相反。
