High-Resolution Enabled 5-plex Mass Defect-Based N, N-Dimethyl Leucine Tags for Quantitative Proteomics

Anal Chem. 2019 Jul 2;91(13):7991-7995. doi: 10.1021/acs.analchem.9b01691. Epub 2019 Jun 10.


A mass defect-based labeling strategy provides high accuracy as an MS1-centric quantification method, avoiding the ratio compression that affects isobaric label-based reporter ion quantification. We have developed cost-effective 5-plex mass defect N, N-dimethyl leucine (mdDiLeu) tags for quantification of various biological samples with increased multiplexing at a given resolving power afforded by the addition of mass difference isotopologues. The combination of mass difference and mass defect produces two labeled peak clusters separated by 5 Da in MS1 spectra that are detected as five isotopic peaks at high resolution with mass differences of 15, 17, and 18 mDa per tag. Synthesis of each of the 5-plex mdDiLeu tags is accomplished by a single straightforward reaction step, making it accessible to any lab. To demonstrate 5-plex mdDiLeu for quantitative proteomics, we perform proof-of-principle experiments of mdDiLeu-labeled Saccharomyces cerevisiae lysate digest on an Orbitrap Fusion Lumos mass spectrometer.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Leucine / analogs & derivatives*
  • Methylation
  • Proteomics / methods
  • Saccharomyces cerevisiae / chemistry*
  • Saccharomyces cerevisiae Proteins / analysis*
  • Tandem Mass Spectrometry / methods*


  • Saccharomyces cerevisiae Proteins
  • Leucine