(E)-Propyl α-Cyano-4-Hydroxyl Cinnamylate: A High Sensitive and Salt Tolerant Matrix for Intact Protein Profiling by MALDI Mass Spectrometry
作者:Sheng Wang、Zhaohui Xiao、Chunsheng Xiao、Huixin Wang、Bing Wang、Ying Li、Xuesi Chen、Xinhua Guo
DOI:10.1007/s13361-015-1325-5
日期:2016.4.1
Low-abundance samples and salt interference are always of great challenges for the practical protein profiling by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Herein, a series of carboxyl-esterified derivatives of α-cyano-4-hydroxycinnamic acid (CHCA) were synthesized and evaluated as matrices for MALDI-MS analysis of protein. Among them, (E)-propyl α-cyano-4-hydroxyl cinnamylate (CHCA-C3) was found to exhibit excellent assay performance for intact proteins by improving the detection sensitivity 10 folds compared with the traditional matrices [i.e., super2,5-dihydroxybenzoic acid (superDHB), sinapic acid (SA), and CHCA]. In addition, CHCA-C3 was shown to have high tolerance to salts, the ion signal of myoglobin was readily detected even in the presence of urea (8 M), NH4HCO3 (2 M), and KH2PO4 (500 mM), meanwhile sample washability was robust. These achievements were mainly attributed to improved ablation ability and increased hydrophobicity or affinity of CHCA-C3 to proteins in comparison with hydrophilic matrixes, leading to more efficient ionization of analyte. Furthermore, direct analysis of proteins from crude egg white demonstrated that CHCA-C3 was a highly efficient matrix for the analysis of low-abundance proteins in complex biological samples. These outstanding performances indicate the tremendous potential use of CHCA-C3 in protein profiling by MALDI-MS.
低丰度样品和高盐干扰一直是基质辅助激光解吸/电离质谱(MALDI-MS)实际蛋白质分析中的重大挑战。本文合成并评估了一系列羧酸酯化衍生物α-氰基-4-羟基肉桂酸(CHCA)作为蛋白质MALDI-MS分析的基质。其中,(E)-丙基α-氰基-4-羟基肉桂酸酯(CHCA-C3)被发现具有优异的蛋白质完整性检测性能,其检测灵敏度比传统的基质[即超级2,5-二羟基苯甲酸(superDHB)、丁香酸(SA)和CHCA]提高了10倍。此外,CHCA-C3对盐类有较高的耐受性,即使在存在尿素(8 M)、NH4HCO3(2 M)和KH2PO4(500 mM)的情况下,肌红蛋白的离子信号也很容易被检测到,同时样品的可洗涤性也很强。这些成就主要归因于CHCA-C3与亲水性基质相比,具有更好的消融能力和增加的疏水性或亲和力,从而导致更有效的电离。此外,直接分析粗蛋白表明,CHCA-C3是一种高效的复杂生物样品中低丰度蛋白质分析的基质。这些出色的性能表明CHCA-C3在蛋白质组学中具有巨大的潜在应用价值。