title: Optimized protocol for on-target phosphopeptide enrichment prior to matrix-assisted laser desorption-ionization mass spectrometry using mesoporous titanium dioxide.
abstract: A novel on-target phosphopeptide enrichment method is presented that allows specific enrichment and direct analysis by matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS) of phosphorylated peptides. Spots consisting of a thin film of anatase titanium dioxide are sintered onto a conductive glass surface. Enrichment and analysis can be performed on the modified target with minimal sample handling. The protocol leads to an enrichment efficiency that is superior to what has been reported before for similar methods. The method was tested using beta-casein as a model phosphorylated protein as well as with a custom peptide mixed with its phosphorylated form. A very low detection limit, a significantly improved phosphoprofiling capability, and a simple experimental approach provide a powerful tool for the enrichment, detection, and analysis of phosphopeptides.
authors.affiliation: Department of Physical and Analytical Chemistry, Uppsala University, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Eriksson
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergquist
authors.forename: Katarina
authors.initials: K
authors.lastname: Edwards
authors.forename: Anders
authors.initials: A
authors.lastname: Hagfeldt
authors.forename: David
authors.initials: D
authors.lastname: Malmström
authors.forename: Víctor
authors.initials: V
authors.lastname: Agmo Hernández
mesh_terms: D000595:Amino Acid Sequence; D053000:Analytic Sample Preparation Methods / Q000379:methods*; D000818:Animals; D002364:Caseins / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D016062:Porosity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014025:Titanium / Q000737:chemistry*
chemical_list: D002364:Caseins; D010748:Phosphopeptides; D010750:Phosphoproteins; C009495:titanium dioxide; D014025:Titanium