Copper, zinc superoxide dismutase plus hydrogen peroxide: a catalytic system for human lipoprotein oxidation.
We report for the first time that bovine or human CuZnSOD plus H2O2 can catalyze human lipoprotein oxidation, inducing like free copper ions a typical oxidative kinetics with lag and propagation phases. Free copper released from CuZnSOD by H2O2, but not enzyme peroxidase activity and carbonate radical anion, is responsible for lipoprotein oxidation, which is indeed totally inhibited by copper chelators and BHT but unaffected by bicarbonate. Moreover, lipoprotein oxidation is significantly counteracted by the OH* scavengers formate and azide, which can enter the active site of CuZnSOD and decrease copper release through scavenging of copper-bound OH*; benzoate and ethanol, which cannot enter, are instead ineffective, indicating no oxidative involvement of free OH* escaped from the enzyme active site. The possibility of CuZnSOD/H2O2-catalyzed lipoprotein oxidation in vivo is discussed.
Lapenna
Domenico
D
Dipartimento di Medicina e Scienze dell'Invecchiamento, and Centro di Scienze dell'Invecchiamento-Fondazione Università G. d'Annunzio, Facoltà di Medicina e Chirurgia, Università G. d'Annunzio, 66100 Chieti, Italy. piersd@tiscalinet.it
Ciofani
Giuliano
G
Pierdomenico
Sante Donato
SD
Giamberardino
Maria Adele
MA
Cuccurullo
Franco
F
D000818:Animals; D002384:Catalysis; D002417:Cattle; D003300:Copper / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D005561:Formates / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000378:metabolism; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D019810:Sodium Azide / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000378:metabolism
D005561:Formates; D016166:Free Radical Scavengers; D008074:Lipoproteins; C030544:formic acid; D003300:Copper; D019810:Sodium Azide; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase