Schlosser Gitta, Jakab Annamária, Pocsfalvi Gabriella, Vékey Károly, Hudecz Ferenc, Mezo Gábor
Research Group of Peptide Chemistry, Chemical Research Center, Department of Organic Chemistry, Hungarian Academy of Sciences, Eötvös L. University, Budapest, Hungary.
Rapid Commun Mass Spectrom. 2009 May;23(9):1249-54. doi: 10.1002/rcm.3993.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been used to characterize poly(L-lysine) polymers and unique oligomer peptides, like 10-, 15- and 25-mer [Lys]n oligolysine peptides. Several matrices have been tried in order to find optimal conditions, but only alpha-cyano-4-hydroxycinnamic acid gave analytically useful spectra. The synthetic oligomers and their mixtures gave good quality spectra, showing protonated and cationized molecules, including doubly charged species. The polymers, analogously, gave a wide distribution of single- and double-cationized peak series. The polymer distributions observed indicate the presence of significant suppression effects. The concentration (matrix/analyte ratio) was found to influence the results significantly; distributions shifting to higher masses when higher polymer concentrations were used. This effect was studied in detail using the synthetic ('monodisperse') oligolysine peptides. It was found that the relative intensities change by over an order of magnitude in the 0.1-10 pmol/microL concentration range (typical for most proteomic analyses). The results indicate that concentration effects need to be considered when MALDI-MS is used for quantitative purposes.
基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）已被用于表征聚（L-赖氨酸）聚合物和独特的寡聚肽，如10聚体、15聚体和25聚体[Lys]n寡聚赖氨酸肽。为了找到最佳条件，人们尝试了几种基质，但只有α-氰基-4-羟基肉桂酸给出了具有分析价值的光谱。合成寡聚物及其混合物给出了高质量的光谱，显示出质子化和阳离子化的分子，包括双电荷物种。类似地，聚合物给出了单阳离子化和双阳离子化峰系列的广泛分布。观察到的聚合物分布表明存在显著的抑制效应。发现浓度（基质/分析物比率）对结果有显著影响；当使用较高的聚合物浓度时，分布向较高质量转移。使用合成的（“单分散”）寡聚赖氨酸肽对这种效应进行了详细研究。发现在0.1-10 pmol/μL浓度范围内（大多数蛋白质组学分析的典型浓度范围），相对强度变化超过一个数量级。结果表明，当MALDI-MS用于定量目的时，需要考虑浓度效应。
