title: Inactivation of glucose-6-phosphate dehydrogenase by 4-hydroxy-2-nonenal. Selective modification of an active-site lysine.
abstract: Incubation of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides with 4-hydroxy-2-nonenal (HNE) results in a pseudo first-order loss of enzyme activity. The pH dependence of the inactivation rate exhibits an inflection around pH 10, and the enzyme is protected from inactivation by glucose 6-phosphate. Loss of enzyme activity corresponds with the formation of one carbonyl function per enzyme subunit and the appearance of a lysine-HNE adduct. The data presented in this paper are consistent with the view that the epsilon-amino group of a lysine residue in the glucose 6-phosphate-binding site reacts with the double bond (C3) of HNE, resulting in the formation of a stable secondary amine derivative and loss of enzyme activity. We have described a mechanism by which HNE may, in part, mediate free radical damage. In addition, a method for the detection of the lysine-HNE adduct is introduced.
authors.affiliation: Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: L I
authors.initials: LI
authors.lastname: Szweda
authors.forename: K
authors.initials: K
authors.lastname: Uchida
authors.forename: L
authors.initials: L
authors.lastname: Tsai
authors.forename: E R
authors.initials: ER
authors.lastname: Stadtman
mesh_terms: D000447:Aldehydes / Q000494:pharmacology*; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007934:Leuconostoc / Q000201:enzymology*; D008239:Lysine; D010659:Phenylhydrazines / Q000494:pharmacology*
chemical_list: D000447:Aldehydes; D000596:Amino Acids; D010659:Phenylhydrazines; C004787:2,4-dinitrophenylhydrazine; D005954:Glucosephosphate Dehydrogenase; C027576:4-hydroxy-2-nonenal; D008239:Lysine