title: Oxidative modification of rat liver 5'-nucleotidase: the mechanisms for protection and re-activation.
abstract: The effect of oxidative stress catalysed by transition metals appears to have a critical relevance for the structure and function not only of membrane lipids but also of integral membrane proteins in a complex lipid-protein assembling, and membrane-dependent function. The integral membrane enzyme 5'-nucleotidase is susceptible to Fe((2+))-ion catalysed oxidative modification, and the extent of enzyme inhibition is in inverse relationship (r = -0.820) with lipid peroxidation (MDA) level. This work is also a comparative study about possible effectiveness of different Fe-ion chelators (deferoxamine, Na-citrate, Na-salicylate, ammonium oxalate and EDTA), antioxidants (GSH, GSH/GSH-Px system, Cu, Zn-SOD and mannitol) and metal cations (Mg(2+) and Mn(2+)) to protect or restore Fe(2+)-ion induced 5'-nucleotidase inhibition and to suppress Fe(2+)-ion enhanced lipid peroxidation. Among the examined chelators it was only deferoxamine and Na-citrate that exerted a fully protective and reactivating ability; among the antioxidants it was only GSH; among the metal cations it was only Mn(2+). The ability to protect or restore 5'-nucleotidase activity and to diminish chain-induced lipid peroxidation is explicable in terms of: metal-binding ability, capacity of taking iron away from a biological molecule, or ability of transferring the damage to itself. After a short incubation period, the iron associated with enzyme or lipid hydroperoxides could be in a labile coordinative linkage, still able to interact with possible ligands or metal cations.
authors.affiliation: Institute for Biochemistry, School of Medicine, University of Nis, Yukoslavia. kocicrg@bankerinter.net
authors.forename: G
authors.initials: G
authors.lastname: Kocic
authors.forename: D
authors.initials: D
authors.lastname: Pavlovic
authors.forename: T
authors.initials: T
authors.lastname: Jevtovic
authors.forename: R
authors.initials: R
authors.lastname: Kocic
authors.forename: A
authors.initials: A
authors.lastname: Bojic
authors.forename: P
authors.initials: P
authors.lastname: Vlahovic
authors.forename: V
authors.initials: V
authors.lastname: Djordjevic
authors.forename: D
authors.initials: D
authors.lastname: Sokolovic
authors.forename: B
authors.initials: B
authors.lastname: Djindjic
mesh_terms: D015720:5'-Nucleotidase / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002614:Chelating Agents / Q000378:metabolism; D004789:Enzyme Activation; D005296:Ferrous Compounds / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D007978:Levamisole / Q000494:pharmacology; D015227:Lipid Peroxidation; D008099:Liver / Q000201:enzymology*; D008315:Malondialdehyde / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D051381:Rats
chemical_list: D000975:Antioxidants; D002614:Chelating Agents; D005296:Ferrous Compounds; D007978:Levamisole; D008315:Malondialdehyde; D015720:5'-Nucleotidase