title: Relative quantification of amine-containing metabolites using isobaric N,N-dimethyl leucine (DiLeu) reagents via LC-ESI-MS/MS and CE-ESI-MS/MS.
abstract: Tandem mass spectrometry (MS/MS)-based relative quantification by isobaric labeling is a useful technique to compare different metabolic expression levels in biological systems. For the first time, we have labeled primary and secondary amine-containing small molecules using 4-plex isobaric N,N-dimethyl leucine (DiLeu) to perform relative quantification. Good labeling efficiency and quantification accuracy were demonstrated with a mixture of 12 metabolite standards including amino acids and small molecule neurotransmitters. Labeling amine-containing metabolites with DiLeu reagents also enabled the separation of polar metabolites by nanoRPLC and improved the detection sensitivity by CE-ESI-MS. The 4-plex DiLeu labeling technique combined with LC-MS/MS and CE-MS/MS platforms were applied to profile and quantify amine-containing metabolites in mouse urine. The variability of concentrations of identified metabolites in urine samples from different mouse individuals was illustrated by the ratios of reporter ion intensities acquired from online data-dependent analysis.
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705, USA. lingjun.li@wisc.edu.
authors.forename: Ling
authors.initials: L
authors.lastname: Hao
authors.forename: Xuefei
authors.initials: X
authors.lastname: Zhong
authors.forename: Tyler
authors.initials: T
authors.lastname: Greer
authors.forename: Hui
authors.initials: H
authors.lastname: Ye
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D000588:Amines / Q000032:analysis / Q000737:chemistry / Q000652:urine*; D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods; D056148:Chromatography, Reverse-Phase / Q000379:methods; D007930:Leucine / Q000031:analogs & derivatives* / Q000737:chemistry*; D051379:Mice; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000588:Amines; D007930:Leucine