William H. Bannister

Enhanced production of hydroxyl radicals by the xanthine-xanthine oxidase reaction in the presence of lactoferrin

The generation of hydroxyl radicals by the xanthine-xanthine oxidase reaction (C. Beauchamp and I. Fridovich (1970) J. Biol. Chem. 245, 4641-1616) has been shown to be increased by iron-saturated lactoferrin isolated from pig neutrophils. Hydroxyl radical production, measured by EPR spin trapping and by ethylene production from alpha-keto-gamma-methiol butyric acid, has been demonstrated to be produced by a Fenton-type Haber-Weiss reaction catalysed by lactoferrin. The possibility that lactoferrin catalyses such a reaction in vivo is considered.

THE COMPLETE AMINO ACID SEQUENCE OF HUMAN Cu/Zn SUPEROXIDE DISMUTASE

D. BARRA, F. MARTINI, J. V. BANNISTER*, M. E. SCHININP;, G. ROTILIO, W. I-I. BANNISTER+ and F. BOSSA Istituto di Chimica Biologica e Centro di Biologia Molecolare de1 CNR, University of Rome, Rome, Italy, *Inorganic Chemistry Department, University of Oxford, Oxford OXI 3QR, England and +Nuffield Department of Clinical Biochemistry, Radcliffe Infirmary, University of Oxford, Oxford OX2 6HE, England

Does caeruloplasmin dismute superoxide? No

Caeruloplasmin (ferroxidase, EC 1 .16.3 .l) is a copper containingplasmaa&ycoprotein.Three biological functions have been ascribed to caeruloplasmiri: (a) ferroxidase activity; (b) copper transport and Storage; and (c) maintenance of copper homeostasis in;the tissues. In [l] another function for caeruloplasmin has been proposed. These workers have demohstrated that caeruloplasmin inhibits the reduction of ferricytochrome c and of nitroblue tetrazolium by superoxide produced by the aerobic action of xanthine oxidase on hypoxanthine. Consequently it was proposed that caeruloplasmin may perform the function of scavenging any superoxide that leaks in the plasma where the levels of superoxide are extremely low. Here we report that caeruloplasmin does not catalyse the disproportionation of superoxide anion radicals generated by pulse radiolysis. However, the reduction of the type 1 copper(I1) in caeruloplasmin is observed.

Antioxidant Systems in Tumour Cells: The Levels of Antioxidant Enzymes, Ferritin, and Total Iron in a Human Hepatoma Cell Line

The human hepatoma cell line Hep 3B, which has the hepatitis B virus genome, shows over 80% decrease of copper/zinc superoxide dismutase activity, over 90% decrease of manganese superoxide dismutase activity, over 70% decrease of catalase activity, absence of glutathione peroxidase and glutathione S-transferase activities, over 270-fold increase of ferritin content and 25-fold increase of total iron compared to normal autopsy liver. These conditions of low antioxidant enzyme activities and iron overload are those which support the accumulation of oxygen free-radicals and DNA damage commonly considered to be carcinogenic mechanisms.

The reaction of superoxide radicals with metal picolinate complexes

Abstract α-Picolinic acid, a metabolite of tryptophan, forms stable complexes with copper, iron and zinc. The copper(II) complex was found to dismute superoxide though at a much lower rate than copper/zinc superoxide dismutase. The iron(III) picolinate was found to enhance the rate of formation of hydroxyl radicals through the Haber–Weiss reaction. The zinc(II) picolinate did not react with superoxide. The role of iron(III) picolinate as a possible intracellular catalyst of the Haber-Weiss reaction is discussed.

The Role of Glutathione in Protection against DNA Damage Induced by Rifamycin SV And Copper(II) Ions

Incubation of calf thymus DNA in the presence of rifamycin SV induces a decrease in the absorbance of DNA at 260 nm. The effect, was found to be proportional to the antibiotic concentration and enhanced by copper(II) ions. In the presence of rifamycin SV and copper(II), a significant increase in thiobarbituric acid-reactive (TBA-reactive) material is also observed. This effect is inhibited to different degrees by the following antioxidants: catalase 77%; thiourea 72%; glutathione (GSH) 62%; ethanol 52%; and DMSO 34%, suggesting that both hydrogen peroxide (H2O2) and hydroxyl radicals (OH.) are involved in DNA damage. Rifamycin SV-copper(II) mixtures were also found to induce the production of peroxidation material from deoxyribose and, in this case, glutathione and ethanol were the most effective antioxidant substrates with inhibition rates of 91% and 88% respectively. Electrophoretic studies show that calf thymus DNA becomes damaged after 20 min. incubation in the presence of both agents together and that the damaged fragments run with migration rates similar to those obtained by the metal chelating agent 1,10-phenanthroline. Normal DNA electrophoretic pattern was found to be preserved by catalase, and GSH at physiological concentrations and by thiourea. No protection is observed in the presence of ethanol or DMSO. The results obtained indicate the involvement of different reactive species in the degradation process of DNA due to rifamycin SV-copper(II) complex and emphasize the role of reduced glutathione as an oxygen free radical scavenger.

Molecular and functional properties of myoglobin from a marine turtle (Dermochelys coriacea)

The molecular and functional properties of the ferrous and ferric derivatives of the native and PCMB-reacted main myoglobin component (Mb II) from a marine turtle (Dermochelys coriacea) have been studied. The results are compared with those of other monomeric hemoproteins and have been found to be similar to those of sperm whale myoglobin, considered as a molecular prototype.

ADIPOCYTES DO NOT FALSIFY THE SUPEROXIDE THEORY OF OXYGEN TOXICITY

The superoxide theory of oxygen toxicity [ 1 ] considers the enzyme superoxide dismutase (EC 1.15. I. 1) as an important detoxification enzyme of oxygen metabolism and absence of the enzyme in aerobic cells is an embarassment to the theory [2]. This absence has been reported for 3 aerobic microorganisms, namely, Lactobacillus plantarum [2], Neisseria gonorrhoeae [3] and Mycoplasma pneumoniae [4,5] and for rat adipose tissue [6]. There is also a report of absence of copper/zinc superoxide dismutase in human bone marrow [7]. We have re-examined rat adipose tissue and find that it contains superoxide dismutase identifiable as both copper/zinc and manganese superoxide dismutase.

Cell-free synthesis of human Cu/Zn-superoxide dismutase

1. Introduction Superoxide dismutase (EC 1.15.1.1) discovered by McCord and Fridovich [l] is the only protein known to catalyse the disproportionation of superoxide radicals. It may therefore be an important line of defence against toxicity arising associated with oxygen and its reduction products. Three types of superoxide dismutase are known. These have the copper/zinc, iron or manganese as the active centres. The structure, function and clinical relevance of these enzymes has been considered in [2,3]. The synthesis of the enzyme has been shown to be responsive to oxygen tension in

The inhibition of manganese superoxide dismutase by cacodylate

Abstract Manganese superoxide dismutase is inhibited by cacodylate buffer when assayed using the xanthine—xanthine oxidase system for generating superoxide radicals. No inhibitory effect was observed when the enzyme activity was measured using superoxide generated by pulse radiolysis. Further investigations revealed that the inhibitory effect is due to a cacodylate anion radical produced by the interaction of hydroxyl radicals (generated by the xanthinexanthine oxidase system) and cacodylate anions. The formation of cacodylate radicals by hydroxyl radical activation of cacodylate was investigated by electron paramagnetic resonance spectroscopy. The biochemical use of cacodylate buffers, where hydroxyl radical production is suspected, may generate the formation of highly reactive cacodylate radicals which are potentially toxic to enzyme systems.