title: Desalting of phosphopeptides by tandem polypyrrole-c18 reverse phase micropipette tip (TMTip(PPY-C18)) based on hybrid electrostatic, Π-Π stacking and hydrophobic interactions for mass spectrometric analysis.
abstract: Desalting and concentration of peptides using reverse phase (RP) C18 chromatographic material based on hydrophobic interaction is a routine approach used in mass spectrometry (MS)-based proteomics. However, MS detection of small hydrophilic peptides, in particular, phosphopeptides that bear multiple negative charges, is challenging due to the insufficient binding to C18 stationary phase. We described here the development of a new desalting method that takes the unique properties of polypyrrole (PPY). The presence of positively charged nitrogen atoms under acidic conditions and polyunsaturated bonds in polypyrrole provide a prospect for enhanced adsorption of phosphopeptides or hydrophilic peptides through extra electrostatic and Π-Π stacking interactions in addition to hydrophobic interactions. In tandem with reversed phase C18 chromatographic material, the new type of desalting method termed as TMTip(PPY-C18) can significantly improve the MS detection of phosphopeptides with multiple phosphate groups and other small hydrophilic peptides. It has been applied to not only tryptic digest of model proteins but also the analysis of complex lysates of zebrafish eggs. The number of detected phosphate groups on a peptide ranged from 1 to 6. Particularly, polypyrrole based method can also be used in basic condition. Thus it provides a useful means to handle peptides that may not be detectable in acidic condition. It can be envisioned that the TMTip(PPY-C18) should be able to facilitate the exploration of large scale phosphoproteome.
authors.affiliation: Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei, PR China.
authors.forename: Shi
authors.initials: S
authors.lastname: Zheng
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wang
authors.forename: Jieying
authors.initials: J
authors.lastname: Fu
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Hu
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.forename: Lulu
authors.initials: L
authors.lastname: Huang
authors.forename: Youe
authors.initials: Y
authors.lastname: Zhou
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhong
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D000818:Animals; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D005260:Female; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010063:Ovum / Q000737:chemistry*; D010748:Phosphopeptides / Q000032:analysis*; D010750:Phosphoproteins / Q000032:analysis*; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D055672:Static Electricity; D014357:Trypsin / Q000737:chemistry; D015027:Zebrafish / Q000378:metabolism; D029961:Zebrafish Proteins / Q000032:analysis*
chemical_list: D010748:Phosphopeptides; D010750:Phosphoproteins; D011108:Polymers; D011758:Pyrroles; D029961:Zebrafish Proteins; C067635:polypyrrole; D014357:Trypsin