Improved detection of phosphopeptides by negative ion matrix-assisted laser desorption/ionization mass spectrometry using a proton sponge co-matrix |
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Authors: | Shu Zhang Zhong-Ping Yao |
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Institution: | State Key Laboratory for Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China |
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Abstract: | Analysis of phosphopeptides is an important task in proteomic studies. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a technique very commonly used for such a purpose. Analysis of phosphopeptides by MALDI-MS is, however, still a challenging task due to the low ionization efficiency of phosphopeptides. In this study, we reported that by using a proton sponge 1,8-bis(dimethyl-amino)naphthalene (DMAN) as a co-matrix, detection of phosphopeptides by negative ion MALDI-MS could be greatly improved. Combination of DMAN with another matrix 6-aza-2-thiothymine (ATT) and additive diammonium hydrogen citrate (DHC) allowed much lower limit of detection, significantly reduced signal suppression effects and improved position-to-position reproducibility for detection of phosphopeptides by negative ion MALDI-MS. Potential applications of the matrix system in qualification of phosphopeptides and analysis of proteolytic digests of phosphorylated proteins were also demonstrated in this study. |
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Keywords: | Phosphopeptides MALDI Mass spectrometry Matrix Proton sponge Negative ion |
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