基于MALDI源红外光解离质谱-光谱技术的金属-氨基酸配合物离子的结构研究  

Structure Investigation of Metal Cationized Amino Acid Ions Generated by MALDI Source with Infrared Photodissociation Mass Spectrometry and Spectroscopy

作　　者：马利福 方姗 张凯林[1,2] 冯茹霞 张先燚 孔祥蕾[2,4] MA Li-fu;FANG Shan;ZHANG Kai-lin;FENG Ru-xia;ZHANG Xian-yan;KONG Xiang-lei(School of Precision Instrument and Opto-Eledronics Engineering,Tianjin University,Tianjin 300072,China;State Key Laboratory and Institute of Elemento-Organic Chemistry,Nankai University,Tianjin 300071,China;School of Physics and Electronic Information,Anhui Normal University,Wuhu 241000,China;Innovation Centre of Chemical Science and Engineering,Nankai University,Tianjin 300071,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]南开大学化学学院,元素有机化学国家重点实验室,天津300071 [3]安徽师范大学物理与电子学院,安徽芜湖241000 [4]南开大学化学科学与工程创新中心,天津300071

出　　处：《质谱学报》2020年第3期236-243,I0002,共9页Journal of Chinese Mass Spectrometry Society

基　　金：国家自然科学基金项目(21627801,11704280)资助。

摘　　要：红外光解离(IRPD)质谱-光谱技术是研究气相离子结构的有力工具。本工作结合傅里叶变换离子回旋共振质谱(FT-ICR-MS)和台式光学参量振荡器(OPO)红外激光系统,针对气相中铷-组氨酸和铷-赖氨酸配合物离子进行红外光解离光谱研究。实验中配合物离子通过基质辅助激光解吸电离(MALDI)产生,而非由常用的电喷雾离子源(ESI)产生。光谱结果显示,两种配合物离子[His+Rb]+和[Lys+Rb]+分别在3 500 cm-1和2 935 cm-1处存在最大吸收。通过密度泛函理论(DFT)计算方法对[His+Rb]+的结构进行进一步研究,结果表明,[His+Rb]+离子主要来源于His+Rb-03,而非其最低能量构型His+Rb-01。Infrared photodissociation(IRPD) mass spectrometry-spectroscopy is a powerful method for structure study of ions in the gas phase. In this study, a 7.0 T Fourier transform-ion cyclotron resonance-mass spectrometer(FT-ICR-MS) was combined with a bench top optical parametric oscillator(OPO) IR laser system to study the IRPD spectra of complex ions of Rubidium with Histidine and Lysine, respectively. Different from other relative studies, the ions were generated by a matrix assisted laser desorption ionization(MALDI) source, instead of an electrospray ionization(ESI) source. IRPD mass spectrum of [His+Rb]+ complex ion showed dissociation of the parent ion. The wavenumber of IR laser was scanned from 2 700 to 3 700 cm-1 to obtain a set of IRPD mass spectra. Relative intensities of the photo fragments were calculated and constructed to be the IRPD spectra. The IRPD spectrum for [His+Rb]+ showed only one significant absorption at 3 500 cm-1, while that for [Lys+Rb]+ showed a strong peak at 2 935 cm-1, accompanied with a series of small absorption in the range of 3 000-3 400 cm-1. Difference in IRPD spectra verified that this method could identify structural information of different amino acid containing metal cation in the fashion of spectral features effectively. To identify the structures present in the experiments, DFT calculations were further performed on the isomers of [His+Rb]+ at the B3 LYP/6-311++G(d,p)[LANL2 DZ] level of theory. Optimizations and energetic calculations gave eight stable conformations which belong to two types of structure, non-zwitterionic and zwitterionic. The newly found zwitterionic isomer His+Rb-01 showed the lowest electronic energy at 0 K. However, based on the comparison of obtained IRPD experimental spectra with the calculated spectra, the most possible conformation prevailed here was more likely to be His+Rb-03, instead of the lowest energy isomer of His+Rb-01. The experimental and theoretical results suggested that the [His+Rb]+ would have different structural preference under certa

关 键 词：红外光解离(IRPD)光谱 配合物离子 基质辅助激光解吸电离(MALDI) 傅里叶变换离子回旋共振质谱(FT-ICR-MS) 密度泛函理论(DFT) 

分 类 号：O657.63[理学—分析化学]