Haber and Weiss cycle

It is possible that even more H2O2 is detectable. The erythrocuprein-catalyzed disproportionation of OF is probably fast enough to minimize other reactions of OF in the assay system, while in the slower spontaneous disproportionation some of the OF may be lost, for example, via the cycle of Haber and Weiss (167). 

These four reactions were terms the Haber- Weiss cycle despite two reactions being proposed by Haber and Willstadter (1931). Indeed, the only paper by Haber and Weiss (1934) was written in English and the other papers, published in German by Haber et al., were almost ignored (Koppenol 2001). Moreover, the third reaction in this cycle (5.118) was considered inefficient (George 1947, Barb et al. 1949), and... 

In this classical Haber-Weiss cycle iron is being reduced by superoxide anion radical (02T), ascorbic acid or glutathione and subsequently decomposes hydrogen peroxide - formed by spontaneous dismutation of 02T - in the Fenton reaction to produce 0H. This iron-driven 0H formation has a stringent requirement for an available iron coordination site, a sine qua non met not only by hexaaquoiron(III) but by most iron chelates (28). Thus, Fe-EDTA, -EGTA, and -ATP retain a reactive coordination site and catalyze the Haber-Weiss cycle. Phytic acid, however, occupies all available iron coordination sites and consequently fails to support 0H generation (Figure 6). 

Koppenol, W.H., Butler, J., and Van Leeuwen, J.W.L., The Haber-Weiss cycle, Photo-chem. Photobiol., 28, 655-660, 1978. 

Koppenol, W. H. (2001) The Haber-Weiss cycle - 70 years later. Redox Report 6, 229-234 Koppmann, R., A. Khedim, J. Rudolph, D. Poppe, M.O. Andreae, G. Helas, M. Welling and... 

During a cell s normal life cycle under aerobic conditions, some of the consumed oxygen is reduced to highly reactive molecules called reactive oxygen species (ROS). Transition metal ions such as iron, with their frequently unpaired electrons, act as excellent catalysts for the creation of ROS. The body s inability to modulate free iron availability creates an environment prone to the formation of ROS and free-radical induced cellular damage in the event of iron overload. The classical reaction between Fe3+ and superoxide (02 ) is known as the Haber-Weiss reaction ... 

Superoxide radicals are inevitably photoproduced in chloroplasts, and hydrogen peroxide is formed from superoxide. Hydrogen peroxide not only inhibits the enzymes for the cycle of carbon dioxide fixation, but also produces the hydroxyl radical by metal-catalyzed Haber-Weiss reaction (1). AsA peroxidase takes an important part in scavenging hydrogen peroxide in chloroplasts (1), which lack catalase and glutathione peroxidase (2). We have purified two types of AsA peroxidase from tea leaves (3), and one of them (isoz3nne II) is localized in chloroplasts (4, Chen and Asada, unpublished). 

N,/V-bis (2-hydroxybenzyl) ethylenediamine-N,N -diacetic acid (HBED) facilitated Fe(II) oxidation but blocked 02 -induced reduction of Fe(III) and consequently pre-empted production of HO or hypervalent iron through the Haber-Weiss reaction cycle (Samuni et al. 2001). The efficacy of HBED as a 1-electron donor was demonstrated by reduction of the 2,2 -azino-bis(3-ethylbenzothiazoline-6-sul-phonate)-derived nitrogen-centred radical cation (ABTS ), accompanied with a short-lived phenoxy radical. 

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