Accelerated CuZn-SOD-mediated oxidation and reduction in the presence of hydrogen peroxide.
Copper, zinc-superoxide dismutase (CuZn-SOD) is a cytosolic, antioxidant enzyme that scavenges potentially damaging superoxide radical (()O(2)(-)). Under the proper conditions, CuZn-SOD also catalyzes the oxidation and reduction of certain small molecules. Here, we demonstrate that increased exposure to hydrogen peroxide (H(2)O(2)), a by-product of the ()O(2)(-) scavenging reaction, dramatically increases the ability of CuZn-SOD to oxidize melatonin and reduce S-nitrosoglutathione (GSNO). After a 15min in vitro incubation with CuZn-SOD and 1mM H(2)O(2), 76% of the melatonin was oxidized, compared to 52% with 0.25mM H(2)O(2), and just 9% without H(2)O(2). Pre-incubation with 1mM H(2)O(2) resulted in a 100% increase in the rate of GSNO breakdown by CuZn-SOD in the presence of glutathione (GSH) compared to untreated CuZn-SOD. Collectively, these data suggest that even small increases in intracellular H(2)O(2) levels may result in the oxidation and/or reduction of small molecules critical for proper cellular function.
Johnson
Michael A
MA
Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22904, USA. maj5j@email.unc.edu
Macdonald
Timothy L
TL
D001665:Binding Sites; D003300:Copper / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008550:Melatonin / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D026422:S-Nitrosoglutathione / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
D020030:Nitric Oxide Donors; D016877:Oxidants; D013481:Superoxides; D026422:S-Nitrosoglutathione; D003300:Copper; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D005978:Glutathione; D008550:Melatonin