Catalases coordinated ligand reaction

Thus, there appear to be analogies with the six-coordinate high-spin Fe(III) heme of the catalase with tyrosinate ligand [3], The green color of A1203 with applied hemin chloride is transformed to yellow after the catalase reaction, and the resonance Raman spectrum of the spent sample indicates at least partial intactness of the heme part. 

It is well know that copper(II) labile complexes are most widely spread in nature as catalysts of oxidation-reduction reactions and in this sense probably they take second place after iron complexes. On the other hand, however, the copper chelate complexes do not act as catalysts of oxidation, but very often are among the most effective inhibitors of the oxidation reactions. The differences in their catalytic properties may be explained by the fact that all four coordination positions of the central ion are occupied by the chelate ligands. This was demonstrated by Siegel(l) by studying the catalase and peroxidase action of some copper chelate complexes (see scheme 1 in the next page). It was established that the above rate constants sharply decrease in the order I>>II>III of the following scheme and almost reach zero on coordination of the four ligand atoms. 

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