title: Baseline mass resolution of peptide isobars: a record for molecular mass resolution.
abstract: Baseline resolution of two peptides, RVMRGMR and RSHRGHR, of neutral monoisotopic mass, approximately 904 Da, has been achieved by microelectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry at a mass resolving power of approximately 3 300 000. The elemental compositions of these molecules differ by N40 vs. S2H8 (0.000 45 Da), which is less than one electron's mass (0.000 55 Da)! This result establishes a new record for the smallest resolved mass difference between any two molecules. This achievement is made possible by a combination of high magnetic field (9.4 T), large-diameter (4-in.) Penning trap, and low ion density. The implications for proteomics based on accurate mass measurements are discussed briefly.
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, Tallahassee 32310, USA.
authors.forename: F
authors.initials: F
authors.lastname: He
authors.forename: C L
authors.initials: CL
authors.lastname: Hendrickson
authors.forename: A G
authors.initials: AG
authors.lastname: Marshall
mesh_terms: D000595:Amino Acid Sequence; D013058:Mass Spectrometry / Q000379:methods; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010455:Peptides