Radicals myoglobin

In order to understand the potential for haem proteins to mediate the oxidative modification of LDLs, the interaction between ruptured erythrocytes (Paganga et al., 1992) and ruptured myocytes (Bourne etal., 1994) with LDL has been explored. Previous studies from this group have demonstrated that ferryl myoglobin radicals and ruptured cardiac myocytes, which generate ferryl myoglobin species on activation (Turner et al., 1990,... 

Fig. 4.5. ESR spectrum of the ferryl myoglobin radical (Turner et al., 1990). ESR spectrum observed on reaction of (a) metmyoglobin (225 //M) and (b) oxymyoglobin with 250 / M hydrogen peroxide in the presence of 25 mM DMPO at pH 7.4 under normoxic...

These equations are applicable to ferryl myoglobin radical production in chemical systems, but the results are less clear when applied to cellular systems such as cardiac myocytes. A better spectroscopic approach here is to observe the shifts in the Soret region to detect qualitatively the presence of ferryl myoglobin (Turner et al., 1991). Fig. 4.6 shows the comparison between the visible spectra of metmyoglobin... 

Hard, S. and Kanner, J. (1989). Haemoglobin and myoglobin as inhibitors of hydroxyl radical generation in a model system of iron redox cycle. Free Rad. Res. Commun, 6, 1-10. 

Konovalova, T. A., L. D. Kispert et al. (2004). Multifrequency high-field electron paramagnetic resonance characterization of the peroxyl radical. Location in horse heart myoglobin oxidized by H202. J. Phys. Chem. BIOS 11820-11826. 

Compared with Molsidomine, both SIN-1 and SIN-1A are reported to induce similar, but more rapid hypotensive action [95, 96]. SIN-1A, after undergoing oxidation in the presence of oxygen or, in vivo, possibly by redox-active enzymes such as cytochrome C [97, 98] or by reaction with ferric myoglobin formed during reperfusion injury [99], releases NO through an intermediate radical cation. 

Electron transfer to the protein metal center is monitored spectroscopically. In the case of a heme (FeP), a fast increase in absorbance due to direct reduction of Fe(III)P by Ru(bpy)f is followed by a slower increase in absorbance due to reduction of Fe(III)P by the Ru(II) on the protein surface. Control flash experiments with unmodified proteins show only the fast initial increase in absorbance due to Fe(III)P reduction by Ru(bpy)3. Such control experiments demonstrate for horse heart cytochrome c [21], azurin [28], and sperm whale myoglobin [14] that slow reduction of the heme by the EDTA radical produced in the scavenging step does not occur in competition with intramolecular ET. However, for Candida krusei cytochrome c, the control experiment shows evidence for slow EDTA radical reduction of the heme after initial fast reduetion by Ru(bpy)i+ [19]. 

Hemoglobin, myoglobin, cytochrome C, and cytochrome oxidase are all electrochemically reduced in the presence of quinoxaline. Quinoxaline is preferentially reduced to the anion radical that can release its electron. Metalloproteins can serve as the electron acceptors in which the metal ion is reduced [424]. 

Spin trapping has also been applied to the investigation of lipid peroxidation catalysed by myoglobin in linoleate emulsions,204 as well as the oxidation of phospholipids in low-density lipoproteins (18.1) by HOC1.205 Hiramoto et al. have shown that, by quenching the attacking radicals, linoleic acid can protect DNA from oxidation.206 Lipid peroxidation has also been monitored by spin labelling.207... 

This Fe(IV)-derivative is particularly stable with leghemoglobin, while with other hemoglobins and with myoglobins the oxy form is regenerated with H2O2 The reaction of sufficient concentrations of H Oj with methemoglobin could formally yield the OH radical ... 

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