Hemoproteins reaction with hydrogen peroxide

It has been shown above that the catalytic action of catalase and peroxidase is intimately connected with the ability of these hemoproteins to form complexes with hydrogen peroxide (or alkyl peroxides). By choosing the experimental conditions the existence of three different complexes can be demonstrated spectroscopically. The chemical nature of these complexes is as yet unknown, and mechanisms have been represented as bimolecular reactions between substrate and complex. 

It may be concluded from this discussion that heme, hemochromogens, and the hemoproteins could undergo similar free radical and electron transfer reaction as the free ferrous and ferric ions. On thermochemical grounds reactions (1), (3), and (4) should be very rapid and reactions (o) and (a) should be more rapid than with ferrous ion in contrast to reaction (i), the ferric form reacting with hydrogen peroxide which should proceed extremely slowly. 

It is the reaction of the ferric forms of these hemoproteins with hydrogen peroxide that provides the sharpest contrast to ionic iron. Complexes are formed in both systems. Although ferric ion only gives an ion pair complex Fe02H2+, whereas peroxidase can give three com-... 

Peroxidases (EC 1.11.1.7). Peroxidases are hemoproteins, produced mainly by microorganisms and plants, which catalyze oxidation of the recalcitrant nonphenolic lignin units in the presence of hydrogen peroxide (Duran and Esposito, 2000). This is possible because of the formation of a high redox potential oxo-ferryl intermediate during the reaction of the heme cofactor with H202 (Martinez et al., 2005). Dubey et al. (1998) studied the polymerization of catechol by plant peroxidases and found that the resultant polymers consisted of phenylene and oxyphenylene units (Figure 2.14). 

In the editorial preface to the first volume of Advances in Catalysis the decision was made known not to publish reviews of specialized topics in biocatalysis but from time to time to bring reports in which the relationship and parallelism between this special field and normal catalysis are discussed. This is the first of these reports. Its purpose is to examine the reactions of four hemoproteins, hemoglobin, myoglobin, peroxidase, and catalase, which all contain the same coordination compound of iron—ferrous or ferric protoporphyrin attached to different protein molecules, with oxygen, hydrogen peroxide, and in a few cases additional reducing substances. Some of these reactions are specific ... 

There are some further aspects of the ionic iron-hydrogen peroxide system which have a possible bearing on hemoprotein reactions. Apart from the reactions of the HO radical listed above (1 and 2) and reactions with oxidizable or polymerizable substrates, there is some experimental evidence that two additional types of reaction may occur. The first... 

Consideration of the possibility of similar free radical reactions occurring with the hemoproteins according to this thermochemical data suggests that the ferrous compounds should react as rapidly or more rapidly than free ferrous ions. The ferric compounds reacting with HO 2 radical or 02- should still be rapid reactions but in the case of hydrogen peroxide or 02H- the reaction should proceed extremely slowly. 

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