title: Difference in mass analysis using labeled lysines (DIMAL-K): a new, efficient proteomic quantification method applied to the analysis of astrocytic secretomes.
abstract: Here we describe an original strategy for unbiased quantification of protein expression called difference in mass analysis using labeled lysine (K) (DIMAL-K). DIMAL-K is based on the differential predigestion labeling of lysine residues in complex protein mixtures. The method is relevant for proteomic analysis by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. Protein labeling on lysine residues uses two closely related chemical reagents, S-methyl thioacetimidate and S-methyl thiopropionimidate. Using protein standards, we demonstrated that 1) the chemical labeling was quantitative, specific, and rapid; 2) the differentially labeled proteins co-migrated on two-dimensional gels; and 3) the identification by mass fingerprinting and the relative quantification of the proteins were possible from a single MALDI-TOF mass spectrum. The power of the method was tested by comparing and quantifying the secretion of proteins in normal and proinflammatory astrocytic secretomes (20 microg). We showed that DIMAL-K was more sensitive and accurate than densitometric image analysis and allowed the detection and quantification of novel proteins.
authors.affiliation: Département de Neurobiologie, Institut de Génomique Fonctionnelle, 141 rue de la cardonille, 34094 Montpellier Cedex 5, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Delcourt
authors.forename: Patrick
authors.initials: P
authors.lastname: Jouin
authors.forename: Joël
authors.initials: J
authors.lastname: Poncet
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Demey
authors.forename: Eric
authors.initials: E
authors.lastname: Mauger
authors.forename: Joël
authors.initials: J
authors.lastname: Bockaert
authors.forename: Philippe
authors.initials: P
authors.lastname: Marin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Galéotti
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000737:chemistry*; D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional; D007553:Isotope Labeling; D008239:Lysine / Q000737:chemistry*; D051379:Mice; D010446:Peptide Fragments / Q000032:analysis*; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010446:Peptide Fragments; D020543:Proteome; D008239:Lysine