Superoxide bovine

Water soluble protein with a relative molecular mass of ca. 32600, which particularly contains copper and zinc bound like chelate (ca. 4 gram atoms) and has superoxide-dismutase-activity. It is isolated from bovine liver or from hemolyzed, plasma free erythrocytes obtained from bovine blood. Purification by manyfold fractionated precipitation and solvolyse methods and definitive separation of the residual foreign proteins by denaturizing heating of the orgotein concentrate in buffer solution to ca. 65-70 C and gel filtration and/or dialysis. 

Hodgson, E.K. and Friedovich, I. (1975). The interaction of bovine erythrocyte superoxide dismutase with hydrogen peroxide Chemiluminescence and peroxidation. 

FIGURE 10.5 (a) MALDI-TOF MS analysis of the apo-form of bovine Cu, Zn superoxide... 

The imidazolate bridged Cu/Zn bimetallic complex of the cryptand (13) was structurally characterized and shown to have a Cu-Zn distance of 5.93 A (native Cu, Zn-SOD 6.2 A).146 The complex shows some activity in the dismutation of superoxide at biological pH that is retained in the presence of bovine serum albumin. 

FIGURE 10.6 Comparison of solid-state and liquid-state spectra from a copper protein. The figure illustrates shifts in apparent gz and Az-values of the S = 1/2 and I =3/2 spectrum from Cu11 in bovine superoxide dismutase as a function of the surrounding medium. Top trace frozen aqueous solution at 60 K middle trace frozen water/glycerol (90/10) solution at 60 K bottom trace aqueous solution at room temperature. (Modified from Hagen 1981.)... 

J.S. Valentine, M.W. Pantoliano, PJ. Mcdonnell, A.R. Burger, and S.J. Lippard, pH-dependent migration of copper(II) to the vacant zinc-binding site of zinc-free bovine erythrocyte superoxide dismutase. Proc. Natl. Acad. Sci. U.S.A. 76, 4245-4249 (1979). 

J.A. Fee, R. Natter, and G.S.T. Baker, Reconstitution of bovine erythrocyte superoxide dismutase. II. Observations on the nature of catalyzed superoxide. Biochim. Biophy. Acta. 295, 96-106 (1973). 

R.N. Iyer and W.E. Schmidt, Observations on the direct electrochemistry of bovine copper-zinc superoxide dismutase. Bioelectrochem. Bioenerg. 27, 393 104 (1992). 

J.A. Fee and P.E. DiCorleto, Oxidation-reduction properties of bovine erythrocyte superoxide dismutase. Biochemistry. 12, 4893-4899 (1973). 

M.E. Me Adam, E.M. Fielden, F. Favelle, F. Calabrese, D. Cocco, and G. Rotilio, The involvement of the bridging imidazolate in the catalytic mechanism of action of bovine superoxide dismutase. 

At the beginning only XO and not XDH was considered as a superoxide producer. For example, in 1985 McCord [19] suggested that the conversion of XDH into XO is responsible for an increase in superoxide production in postischemic reperfusion injury. However, it has later been shown [20,21] that XDH itself is a producer of superoxide although not so effective as XO. Moreover, the efficiency of superoxide production differs for different types of the enzyme. Thus, 2.8 to 3.0 mol of superoxide were produced by chicken liver XDH, while superoxide production by bovine milk XDH was insignificant [21]. Sanders et al. [22] found that NADH oxidation by human milk and by bovine milk XDHs catalyzed superoxide production more rapidly than XO this process was inhibited by NAD and diphenyleneiodo-nium but not by the established XO inhibitors allopurinol and oxypurinol. 

Such a process is supposed to occur within the limits of Q-cycle mechanism (Figure 23.2). In accord with this scheme ubihydroquinone reduced dioxygen in Complex III, while superoxide producers in Complex I could be FMN or the FeS center [12]. Zhang et al. [24] also suggested that the Q-cycle mechanism is responsible for the superoxide production by the succinate-cytochrome c reductase in bovine heart mitochondria and that FAD of succinate dehydrogenase is another producer of superoxide. Young et al. [25] concluded that, in addition to Complex III, flavin-containing enzymes and FeS centers are also the sites of superoxide production in liver mitochondria. 

As a rule, oxygen radical overproduction in mitochondria is accompanied by peroxidation of mitochondrial lipids, glutathione depletion, and an increase in other parameters of oxidative stress. Thus, the enhancement of superoxide production in bovine heart submitochondrial particles by antimycin resulted in a decrease in the activity of cytochrome c oxidase through the peroxidation of cardiolipin [45]. Iron overload also induced lipid peroxidation and a decrease in mitochondrial membrane potential in rat liver mitochondria [46]. Sensi et al. [47] demonstrated that zinc influx induced mitochondrial superoxide production in postsynaptic neurons. 

As described earlier, superoxide is a well-proven participant in apoptosis, and its role is tightly connected with the release of cytochrome c. It has been proposed that a switch from the normal four-electron reduction of dioxygen through mitochondrial respiratory chain to the one-electron reduction of dioxygen to superoxide can be an initial event in apoptosis development. This proposal was supported by experimental data. Thus, Petrosillo et al. [104] have shown that mitochondrial-produced oxygen radicals induced the dissociation of cytochrome c from bovine heart submitochondrial particles supposedly via cardiolipin peroxidation. Similarly, it has been found [105] that superoxide elicited rapid cytochrome c release in permeabilized HepG2 cells. In contrast, it was also suggested [106] that it is the release of cytochrome c that inhibits mitochondrial respiration and stimulates superoxide production. 

Superoxide generation was detected via the NADPH-dependent SOD-inhibitable epinephrine oxidation and spin trapping [15,16], Grover and Piette [17] proposed that superoxide is produced equally by both FAD and FMN of cytochrome P-450 reductase. However, from comparison of the reduction potentials of FAD (-328 mV) and FMN (190 mV) one might expect FAD to be the most efficient superoxide producer. Recently, the importance of the microsomal cytochrome h558 reductase-catalyzed superoxide production has been shown in bovine cardiac myocytes [18]. 

High antioxidative activity carvedilol has been shown in isolated rat heart mitochondria [297] and in the protection against myocardial injury in postischemic rat hearts [281]. Carvedilol also preserved tissue GSL content and diminished peroxynitrite-induced tissue injury in hypercholesterolemic rabbits [298]. Habon et al. [299] showed that carvedilol significantly decreased the ischemia-reperfusion-stimulated free radical formation and lipid peroxidation in rat hearts. Very small I50 values have been obtained for the metabolite of carvedilol SB 211475 in the iron-ascorbate-initiated lipid peroxidation of brain homogenate (0.28 pmol D1), mouse macrophage-stimulated LDL oxidation (0.043 pmol I 1), the hydroxyl-initiated lipid peroxidation of bovine pulmonary artery endothelial cells (0.15 pmol U1), the cell damage measured by LDL release (0.16 pmol l-1), and the promotion of cell survival (0.13 pmol l-1) [300]. SB 211475 also inhibited superoxide production by PMA-stimulated human neutrophils. 

Later on, the importance of xanthine oxidase as the producer of reoxygenation injury was questioned at least in the cells with low or no xanthine oxidase activity. Thus, it has been shown that human and rabbit hearts, which possess extremely low xanthine oxidase activity, nonetheless, develop myocardial infractions and ischemia-reperfusion injury [9], However, recent studies supported the importance of the xanthine oxidase-catalyzed oxygen radical generation. It has been showed that xanthine oxidase is partly responsible for reoxygenation injury in bovine pulmonary artery endothelial cells [10], human umbilical vein and lymphoblastic leukemia cells [11], and cerebral endothelial cells [12], Zwang et al. [11] concluded that xanthine dehydrogenase may catalyze superoxide formation without conversion to xanthine oxidase using NADH instead of xanthine as a substrate. 

Bovine copper-cobalt superoxide dismutase, activity, 45 152-153... 

Bacillus subtilis defense mechanism, 610 bovine semm albumin y-radiation, 614 generation inhibition, 612 hydroperoxide synthesis, 315, 320 ludgenin oxidation, 645, 1250-1 luminol oxidation, 643, 644, 1242-4 organic sulfur compounds, 1032-9 ozone water disinfection, 606 peroxynitrite generation, 10, 611-12 Superoxide dismutase (SOD)... 

Enzymes and Coenzymes Electrochemical behavior of bovine erythrocyte superoxide dismutase adsorbed on Hg electrode has been studied by Qian... 

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