Direct identification of tyrosine sulfation by using ultraviolet photodissociation mass spectrometry.
Sulfation is a common post-translational modification of tyrosine residues in eukaryotes; however, detection using traditional liquid chromatography-mass spectrometry (LC-MS) methods is challenging based on poor ionization efficiency in the positive ion mode and facile neutral loss upon collisional activation. In the present study, 193 nm ultraviolet photodissociation (UVPD) is applied to sulfopeptide anions to generate diagnostic sequence ions, which do not undergo appreciable neutral loss of sulfate even using higher energy photoirradiation parameters. At the same time, neutral loss of SO₃ is observed from the precursor and charge-reduced precursor ions, a spectral feature that is useful for differentiating tyrosine sulfation from the nominally isobaric tyrosine phosphorylation. LC-MS detection limits for UVPD analysis in the negative mode were determined to be around 100 fmol for three sulfated peptides, caerulein, cionin, and leu-enkephalin. The LC-UVPD-MS method was applied for analysis of bovine fibrinogen, and its key sulfated peptide was confidently identified.
Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX, 78712, USA.
Michelle R
MR
Robinson
Kevin L
KL
Moore
Jennifer S
JS
Brodbelt
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002108:Ceruletide / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D062126:Databases, Chemical; D055664:Electrochemical Techniques; D004743:Enkephalin, Leucine / Q000737:chemistry / Q000378:metabolism; D005340:Fibrinogen / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007834:Lasers; D057230:Limit of Detection; D013058:Mass Spectrometry; D008832:Microchemistry; D009479:Neuropeptides / Q000737:chemistry / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D056951:Photoelectron Spectroscopy; D011499:Protein Processing, Post-Translational; D013431:Sulfates / Q000032:analysis* / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D014443:Tyrosine / Q000032:analysis* / Q000737:chemistry
D009479:Neuropeptides; D009842:Oligopeptides; D010446:Peptide Fragments; D013431:Sulfates; C063059:cionin; D014443:Tyrosine; D004743:Enkephalin, Leucine; D002108:Ceruletide; D005340:Fibrinogen