Towards the development of a covalently tethered MALDI system - A study of allyl-modified MALDI matrixes
Towards the development of a covalently tethered MALDI system - A study of allyl-modified MALDI matrixes
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DOI：
10.1139/v06-185
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发表时间：
2007-01-01
影响因子：
1.1
通讯作者：
Nagy, Noemi
中科院分区：
文献类型：
--
作者：
Martic, Sanela;Brennan, John D.;Nagy, Noemi
基质辅助激光解吸电离 (MALDI) 质谱的一个新兴应用是低分子量 (LMW) 化合物的分析，通常通过耦合液相色谱 - MALDI-MS 方法进行。然而，在许多情况下，MALDI 质谱的低分子量区域被源自基质的信号所掩盖，这表明可能需要开发束缚的 MALDI 基质来优化此类化合物的 MS 性能。为了深入了解 MALDI 基质共价连接的潜在位点，我们系统地研究了各种官能团基序在确定三种常见 MALDI 基质的基质效率中所发挥的作用，通过一组 LMW 化合物的基质分解的总信号强度和背景噪声来判断。制备了一系列标准基质的烯丙基衍生物，并测量了这些材料在MALDI实验中的效率。对已建立的基质（例如 2,5-二羟基苯甲酸 (DHB)、α-氰基-4-羟基肉桂酸 (CHCA) 和咖啡酸 (CA)）或相近类似物的所有修饰都会导致绝对信号强度和信号背景水平降低。通常在以下情况下观察到性能的改善：(i) 酚基团的存在（羧酸效果较差）（ii）结晶衍生物，以及（iii）在接近激发激光（337 nm）的波长下具有高消光系数的化合物。最有趣的衍生物是咖啡酸的 O-烯丙基醚 (15) 和 N-烯丙基酰胺 (16)。这些化合物不会促进所有四种测试分析物的信号。然而，观察到的光谱中来自基质的信号少于来自母体化合物 CA 的信号。这些化合物表明，MALDI 基质的功能化，最终产生束缚基质，是可能的，而不会损害信号强度。
An emerging application of matrix-assisted laser desorption ionization (MALDI) mass spectrometry is the analysis of low molecular weight (LMW) compounds, often via coupled liquid chromatography - MALDI-MS methods. However, in many cases, the low molecular weight region of MALDI mass spectra is obscured by the presence of signals originating from the matrix, suggesting that the development of tethered MALDI matrixes may be required to optimize MS performance for such compounds. To gain insight into potential sites for covalent attachment of MALDI matrixes, we have systematically investigated the role played by a variety of functional group motifs in determining matrix efficiency for three common MALDI matrixes, as judged both by total signal intensity and background noise from matrix decomposition for a set of LMW compounds. A series of allyl derivatives of standard matrixes was prepared, and the efficiency of these materials in the MALDI experiment was measured. All modifications of established matrixes, e.g., 2,5-dihydroxybenzoic acid (DHB), alpha-cyano-4-hydroxycinnamic acid (CHCA), and caffeic acid (CA), or close analogues led to decreased absolute signal intensity and signal-to-background levels. Improved performance was generally observed with (i) the presence of a phenolic group (carboxylic acids were less effective) (ii) crystalline derivatives, and (iii) compounds that had high extinction coefficients at wavelengths near to that of the exciting laser (337 nm). The most interesting derivatives were the O-allyl ether (15) and N-allyl amide (16) of caffeic acid. These compounds did not facilitate signals from all four analytes tested. However, the observed spectra contained fewer signals from the matrix than from the parent compound CA. These compounds demonstrate that functionalization of MALDI matrixes, ultimately leading to tethered matrixes, is possible without jeopardizing signal intensity.