title: [Evaluation of isotopic labeling of lysine residues of peptides for quantitative proteomics].
abstract: To evaluate the reagent 2-methoxy-4,5-dihydro-1H-imidazole used for isotopic labeling in quantitative proteomics, we synthesized 2-methoxy-4,5-dihydro-1H-imidazole and its tetradeuterated analog in three steps. Prior to tryptic cleavage, bovine serum albumin (BSA) was reduced and alkylated. Tryptic peptides were derivatized with an equal volume of either DO or D4 and D4-derivatized peptides were mixed with at variable ratio (from 10:1 to 1:5) prior to MS and MS/MS analysis. We used matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and Electro spray ionization-mass spectrometry (ESI-MS) to evaluate the quantitative capability of labeling. The specificity of the reagent is excellent: only lysine side chains were modified among tryptic peptides. MALDI and ESI ionization modes not only could achieve the quantification of differentially expressed proteins but also facilitate the de novo sequencing. This side-chain modification can be used for quantitative analysis with proteomic strategies involving liquid chromatography. Reverse phase liquid chromatography (RPLC) kept a good resolution, and the introduction of D atoms did not introduce a variation of retention time between heavy and light peptides in RPLC.
authors.affiliation: Zhongshan Hospital, Institute of Biomedical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Gao
authors.forename: Lu
authors.initials: L
authors.lastname: Sun
authors.forename: Kun
authors.initials: K
authors.lastname: Guo
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yinkun
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Kang
mesh_terms: D007093:Imidazoles / Q000737:chemistry; D007553:Isotope Labeling / Q000379:methods*; D008239:Lysine / Q000737:chemistry*; D010455:Peptides / Q000032:analysis / Q000737:chemistry*; D040901:Proteomics / Q000379:methods*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: C447410:2-methoxy-4,5-dihydro-1H-imidazole; D007093:Imidazoles; D010455:Peptides; D012710:Serum Albumin, Bovine; D008239:Lysine