Department of Chemistry, Miami University, Oxford, Ohio, USA.
J Am Soc Mass Spectrom. 1996 Dec;7(12):1203-10. doi: 10.1016/S1044-0305(96)00113-4.
The gas-phase basicities (GB) of histidine, lysine, and di- and triglycyl peptides containing either one histidine or one lysine residue have been determined. In all, 12 compounds were examined in a Fourier transform ion cyclotron resonance mass spectrometer. The GBs of the biomolecules were evaluated by proton transfer reactions employing a range of reference compounds with varying gas-phase basicities. In addition, the GBs were determined by using the kinetic method of collision-induced dissociation on a proton-bound dimer containing the peptide and a reference compound. The GBs of histidine and lysine were both found to be 220.8 kcal/mol via proton transfer reactions. The kinetic method experiments, including dissociation of a proton-bound dimer containing both histidine and lysine, also suggest equivalent GBs for these amino acids. However, the small peptides containing lysine are generally more basic than the corresponding histidine-containing peptides. For the peptides, the data suggest that the protonation site is on the basic side chain functional group of the histidine or lysine residues. The GBs of the di- and tripeptides are dependent upon the location of the basic residue. For example, the GBs of the tripeptides glycylglycyl-L-lysine (GlyGlyLys) and L-lysylglycylglycine (LysGlyGly) were both determined to be 230.7 kcal/mol while a GB of kcal/mol was obtained for glycyl-L-lysylglycine (GlyLysGly). A similar GB trend is seen with the histidine-containing tripeptides. Generally, the GBs obtained by using the kinetic method are slightly higher than those obtained by deprotonation reactions; however, the trends in relative GB values are essentially the same with the two techniques.
已测定含有一个组氨酸或一个赖氨酸残基的二肽和三肽的气相碱性（GB）。在傅里叶变换离子回旋共振质谱仪中检查了总共 12 种化合物。通过质子转移反应使用具有不同气相碱性的一系列参比化合物来评估生物分子的 GB。此外，通过使用包含肽和参比化合物的质子束缚二聚体的碰撞诱导解离的动力学方法来确定 GB。通过质子转移反应发现组氨酸和赖氨酸的 GB 均为 220.8 kcal/mol。包括含有组氨酸和赖氨酸的质子束缚二聚体解离的动力学方法实验也表明这些氨基酸具有等效的 GB。然而，含有赖氨酸的小肽通常比相应的含组氨酸的肽更碱性。对于这些肽，数据表明质子化部位位于组氨酸或赖氨酸残基的碱性侧链官能团上。二肽和三肽的 GB 取决于碱性残基的位置。例如，三肽甘氨酰甘氨酰-L-赖氨酸（GlyGlyLys）和 L-赖氨酰甘氨酰甘氨酸（LysGlyGly）的 GB 均为 230.7 kcal/mol，而甘氨酰-L-赖氨酸（GlyLysGly）的 GB 为 kcal/mol。含组氨酸的三肽也存在类似的 GB 趋势。通常，通过动力学方法获得的 GB 略高于通过去质子化反应获得的 GB；然而，两种技术的相对 GB 值趋势基本相同。
