In vitro effects of peroxynitrite treatment on fish liver catalase activity.
The effect of peroxynitrite (PN), a highly toxic agent, on catalase (CAT) activity in fish liver microsomal homogenates was determined. PN was synthesized by mixing acidic hydrogen peroxide solution with sodium nitrite solution and then adding sodium hydroxide solution into the mixture in order to stabilize the highly labile compound peroxynitrous acid (ONOOH) in peroxynitrite anion form (ONOO(- )). The effect of PN and decomposed peroxynitrite (DPN), prepared by preincubation with HCl, was monitored by using a constant amount of homogenate containing the CAT enzyme. Significant losses were observed in the CAT activity of fish liver enzyme after treatment with PN and also with DPN products, the inhibitory effect of PN being slightly more pronounced than that of DPN. IC(50) values were 5.5 and 8.5 microM for PN and DPN, respectively. The PN inhibition of CAT activity is due to both the effects of the secondary and decomposition products of PN and its nitration and oxidation effects on the amino acid residues of the enzyme.
Sivrikaya
Aybike
A
Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, Trabzon, Turkey.
Kolayli
Sevgi
S
Kucuk
Murat
M
Aliyazicioglu
Rezzan
R
D000818:Animals; D002374:Catalase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D016877:Oxidants / Q000138:chemical synthesis / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010473:Perciformes / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000138:chemical synthesis / Q000494:pharmacology*
D016877:Oxidants; D030421:Peroxynitrous Acid; D002374:Catalase