title: Improved detection of phosphopeptides by negative ion matrix-assisted laser desorption/ionization mass spectrometry using a proton sponge co-matrix.
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.
authors.affiliation: 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.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhong-Ping
authors.initials: ZP
authors.lastname: Yao
mesh_terms: D057230:Limit of Detection; D008855:Microscopy, Electron, Scanning; D010748:Phosphopeptides / Q000032:analysis*; D011522:Protons; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010748:Phosphopeptides; D011522:Protons