Institute of Analytical Chemistry and Food Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
J Mass Spectrom. 2009 Nov;44(11):1596-603. doi: 10.1002/jms.1668.
In this study, we investigated a novel ionic liquid matrix (ILM), namely, the 1,1,3,3-tetramethylguanidinium salt of 2,4,6-trihydroxyacetophenone (THAP). This matrix[1,1,3,3-tetramethylguanidinium 2,4,6-trihydroxyacetophenone (GTHAP)] turned out to be well suited for the matrix-assisted laser desorption/ionization mass spectrometric analysis of glycopeptides and glycans, and overcame the well-known ionization suppression of carbohydrate structures in the presence of peptides. The matrix was evaluated by two different series of experiments, in each case in comparison with the crystalline THAP matrix. In the first set of experiments, mass spectra were taken from unseparated tryptic digests of three glycoproteins taken as model compounds. Even glycopeptides containing short peptide backbones and large carbohydrate moieties gave high signal intensities when using the ILM though they did not appear in the THAP spectra. In the second set of experiments, the total tryptic digests were treated with endoglycosidase PNGase F to cleave off the N-linked glycans. When using the GTHAP matrix, it was possible to detect the glycans with high intensities in the presence of the tryptic peptides, whereas glycan ionization was completely suppressed when measured with the solid matrix THAP. The extent of metastable decay of glycopeptides was reduced when using the ILM. Altogether, GTHAP proved as a useful ILM particularly being superior to solid matrices in the context of glycosylation analysis.
在这项研究中，我们研究了一种新型的离子液体基质（ILM），即 2,4,6-三羟基苯乙酮的 1,1,3,3-四甲基胍盐（THAP）。这种基质[1,1,3,3-四甲基胍 2,4,6-三羟基苯乙酮（GTHAP）]非常适合用于糖肽和聚糖的基质辅助激光解吸/电离质谱分析，克服了在存在肽的情况下碳水化合物结构的电离抑制的已知问题。该基质通过两个不同的实验系列进行了评估，在每个实验中都与结晶 THAP 基质进行了比较。在第一组实验中，从三种糖蛋白的未经分离的胰蛋白酶消化物中获得了质谱，即使是含有短肽骨干和大碳水化合物部分的糖肽，在使用 ILM 时也能给出高信号强度，尽管它们在 THAP 光谱中没有出现。在第二组实验中，将总胰蛋白酶消化物用内切糖苷酶 PNGase F 处理以切断 N-连接的聚糖。当使用 GTHAP 基质时，即使存在胰蛋白酶肽，也可以用高信号强度检测到聚糖，而当用固体基质 THAP 测量时，糖基化完全受到抑制。当使用 ILM 时，糖肽的亚稳衰减程度降低。总之，GTHAP 被证明是一种有用的 ILM，特别是在糖基化分析方面优于固体基质。
