### 新型离子液体基质用于MALDI-MS高效离子化寡糖/糖肽

1. 复旦大学化学系和生物医学研究院 上海 200433
• 投稿日期:2013-03-18 发布日期:2013-04-23
• 通讯作者: 陆豪杰, E-mail: luhaojie@fudan.edu.cn; Fax: 0086-021-54237961 E-mail:luhaojie@fudan.edu.cn
• 基金资助:

项目受国家重点基础研究发展计划(Nos. 2012CB910602, 2012AA020203);国家自然科学基金(Nos. 21025519, 21005020, 31070732)和上海市项目(11XD1400800, 东方学者, B109和20114Y167)资助.

### Novel Ionic Matrices for Enhanced Ionization of Oligosaccharides/Glycopeptides during MALDI-MS Analysis

Kuang Min, Zhang Ying, Yang Pengyuan, Lu Haojie

1. Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433
• Received:2013-03-18 Published:2013-04-23
• Supported by:

Project supported by the National Science and Technology Key Project (Nos. 2012CB910602, 2012AA020203), the National Natural Science Foundation of China (Nos. 21025519, 21005020, 31070732), Shanghai Projects (11XD1400800, Eastern Scholar, B109 and 20114Y167).

Matrix plays a fundamental role in the desorption/ionization process during MALDI MS analysis, thus is closely related to the spectral quality. Nevertheless, it is usually difficult for analytes to disperse homogeneously due to the formation of hot spots, which had become a problem encountered with many of the current matrices. This may result in increased measurement time and hamper the application of MALDI MS. Although many efforts have been devoted to optimize matrix choice for oligosaccharide and glycopeptides analyses, there are few matrices that could work well with them in MALDI MS so far. In this study, a novel class of ionic liquid matrices (IMs) based on trihydroxyacetophenone (THAP) was introduced as potential alternatives to the traditional crystalline matrices and showed superior performance for oligosaccharides and glycopeptides analysis. The combination of pyridine or N,N-dimethylaniline (DMA) with 2',3',4'-trihydroxyacetophenone (2',3',4'-THAP) or 2',4',6'-trihydroxyacetophenone (2',4',6'-THAP) at the molar ratio of 1:1 turned out to be well suited for the analysis of oligosaccharides. Besides, the optimized condition could be achieved by 5-fold dilution of the IMs and adding ammonium citrate dibasic[(NH4)2HCit] as matrix additive. Afterwards, in comparison to signals obtained with traditional solid matrix 2,5-dihydroxybenzoic acid (DHB), substantial improvements in sensitivity were observed by the new IMs. Specifically, signal-to-noise ratios of dextran1000 as well as β-cyclodextrin were enhanced more than 10-fold. Moreover, the complex glycan mixture from the intact glycoprotein of RNase B released by PNGase F could be detected with high sensitivity when 2',3',4'-THAP/DMA functioned as the matrix. The unbiased nature of such IM also made it applicable to analyze glycopeptides derived from 10 ng tryptic digests of horseradish peroxidase (HRP), while it was almost impossible to detect any signals when measured with solid matrix 2',3',4'-THAP. In comparison to methods involving derivatization of oligosaccharides, which are susceptible to contamination and often require tedious purification steps, such technique could be readily used and largely reduce sample losses during analysis. As a consequence, these new IMs are promising to be advantageous in glycosylation analysis by MALDI-TOF MS.