Human neutrophils employ myeloperoxidase to convert alpha-amino acids to a battery of reactive aldehydes: a pathway for aldehyde generation at sites of inflammation

Biochemistry. 1998 May 12;37(19):6864-73. doi: 10.1021/bi972449j.


We have recently demonstrated that activated phagocytes employ the heme protein myeloperoxidase, H2O2, and Cl- to oxidize the aromatic amino acid l-tyrosine to the reactive aldehyde p-hydroxyphenylacetaldehyde. We now present evidence for the generality of this reaction by demonstrating that neutrophils employ the myeloperoxidase-H2O2-Cl- system to oxidize nearly all of the common alpha-amino acids to yield a family of reactive aldehydes. Chemical characterization suggested that reactive carbonyl moieties were generated during amino acid oxidation by myeloperoxidase. The structures of amino-acid-derived aldehydes were confirmed using a variety of mass spectrometric methods. Aldehyde production required myeloperoxidase, H2O2, Cl-, and an amino acid; it was inhibited by heme poisons and catalase. Hypochlorous acid was the apparent oxidizing intermediate because its addition to alpha-amino acids resulted in the formation of the anticipated aldehyde. Stimulated human neutrophils likewise generated aldehydes from all classes of alpha-amino acids by a pathway inhibited by heme poisons and catalase, implicating myeloperoxidase and H2O2 in the cell-mediated reaction. Aldehyde production accounted for a significant fraction of the H2O2 generated by stimulated neutrophils at physiological concentrations of amino acids. Collectively, these results suggest that amino-acid-derived aldehydes represent a product of reactive oxidant species generated by activated phagocytes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldehydes / blood*
  • Amino Acids / blood*
  • Catalysis
  • Chlorides / blood
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Hydrogen Peroxide / blood
  • Hypochlorous Acid / blood
  • Inflammation / blood
  • Neutrophil Activation
  • Neutrophils / enzymology*
  • Neutrophils / pathology
  • Oxidation-Reduction
  • Peroxidase / blood*


  • Aldehydes
  • Amino Acids
  • Chlorides
  • Hypochlorous Acid
  • Hydrogen Peroxide
  • Peroxidase