Dehydroalanine derived from cysteine is a common post-translational modification in human serum albumin

Authors

  • Raphael Bar-Or,

    1. Trauma Research Department, Swedish Medical Center, Englewood, CO, USA
    2. Trauma Research Department, Anthony Central Hospital, Denver, CO, USA
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  • Leonard T. Rael,

    1. Trauma Research Department, Swedish Medical Center, Englewood, CO, USA
    2. Trauma Research Department, Anthony Central Hospital, Denver, CO, USA
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  • David Bar-Or

    Corresponding author
    1. Trauma Research Department, Swedish Medical Center, Englewood, CO, USA
    2. Trauma Research Department, Anthony Central Hospital, Denver, CO, USA
    3. Emergency Department, Swedish Medical Center, Englewood, CO, USA
    • Trauma Research Department, St. Swedish Medical Center, Rm. 4-454, 501 E. Hampden Ave., Englewood, CO 80113, USA.
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Abstract

The conversion of a cysteine residue into dehydroalanine (DHA) in proteins was previously described. This post-translational modification (PTM) can be generated artificially as a result of heat and an alkaline environment. The presence of this PTM on human serum albumin (HSA) in plasma collected from healthy volunteers and critically ill patients as well as in commercially available HSA was studied. Using liquid chromatography/mass spectrometry (LC/MS) and matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS) methods, a fragment containing DHA was identified in the trypsin digest of commercial HSA and isolated HSA from plasma. The sequence (RPC*FSALEVDETYVPK) corresponded to the expected molecular mass and fragmentation pattern of a tryptic peptide of HSA where the cysteine residue (cys487) was modified to DHA. The presence of this common PTM of HSA has potential effects on ligand binding to HSA, plasma clearance of this oxidized form of HSA, protein-protein interactions, and oxidation-reduction potential. Copyright © 2008 John Wiley & Sons, Ltd.

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