title: Evaluation of comprehensive multidimensional separations using reversed-phase, reversed-phase liquid chromatography/mass spectrometry for shotgun proteomics.
abstract: Two-dimensional liquid-chromatographic (LC) separation followed by mass spectrometric (MS) analysis was examined for the identification of peptides in complex mixtures as an alternative to widely used two-dimensional gel electrophoresis followed by MS analysis for use in proteomics. The present method involves the off-line coupling of a narrow-bore, polymer-based, reversed-phase column using an acetonitrile gradient in an alkaline mobile phase in the first dimension with octadecylsilanized silica (ODS)-based nano-LC/MS in the second dimension. After the first separation, successive fractions were acidified and dried off-line, then loaded on the second dimension column. Both columns separate peptides according to hydrophobicity under different pH conditions, but more peptides were identified than with the conventional technique for shotgun proteomics, that is, the combination of a strong cation exchange column with an ODS column, and the system was robust because no salts were included in the mobile phases. The suitability of the method for proteomics measurements was evaluated.
authors.affiliation: Eisai Company Ltd., Laboratory of Core Technology, Ibaraki, Japan.
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nakamura
authors.forename: Junro
authors.initials: J
authors.lastname: Kuromitsu
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Oda
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002853:Chromatography, Liquid / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D036103:Nanotechnology; D040901:Proteomics; D013056:Spectrophotometry, Ultraviolet