title: Glycation of human erythrocyte glutathione peroxidase: effect on the physical and kinetic properties.
abstract: BACKGROUND
  Glutathione peroxidase (GPx) is a significant antioxidant enzyme that plays a key role in protecting the body from reactive oxygen species (ROS) and their toxicity. As a biocatalyst, the enzyme has been shown to reduce hydrogen peroxide to water and lipid hydroperoxides to their respective alcohols. The increased levels of ROS in patients with diabetes have been speculated to arise, in part, from alterations in the activity of glutathione antioxidant enzymes, perhaps, by mechanisms such as the glycation of the protein, in vivo.
  
  
  METHODS
  Under physiological conditions of temperature and pH, we investigated the susceptibility of human glutathione peroxidase to glycation, determined the effects of glycation on the physical and kinetic properties of the enzyme, and identified the protein's vulnerable amino acid sites of glycation.
  
  
  RESULTS
  Circular dichroism, UV and mass spectrometry studies revealed that methylglyoxal and DL-glyceraldehyde are potent glycators of glutathione peroxidase; destabilizing its structure, altering its pH activity and stability profiles and increasing its Km value.
  
  
  CONCLUSIONS
  In comparison to DL-glyceraldehyde, methylglyxol was a more potent glycator of the enzyme and was found to nonenzymatically condense with Arg-177, located near the glutathione binding site of GPx.
authors.affiliation: Department of Chemistry, University of Rhode Island, Kingston, RI 02881, United States.
authors.forename: Sreekanth
authors.initials: S
authors.lastname: Suravajjala
authors.forename: Menashi
authors.initials: M
authors.lastname: Cohenford
authors.forename: Leslie R
authors.initials: LR
authors.lastname: Frost
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Pampati
authors.forename: Joel A
authors.initials: JA
authors.lastname: Dain
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry*; D001665:Binding Sites; D002942:Circular Dichroism; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology; D005979:Glutathione Peroxidase / Q000737:chemistry*; D005985:Glyceraldehyde / Q000737:chemistry*; D006031:Glycosylation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis*; D011485:Protein Binding; D011765:Pyruvaldehyde / Q000737:chemistry*; D012996:Solutions; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature
chemical_list: D010446:Peptide Fragments; D012996:Solutions; D005985:Glyceraldehyde; D011765:Pyruvaldehyde; D001120:Arginine; D005979:Glutathione Peroxidase