Catalase, metal chelate enzyme

Because of the ease with which dimercaptopropanol can be broken down in the body there is a danger that chelation, followed by breakdown, will simply result in the translocation of the metal ions to other tissues such as brain or liver. High doses of dimercaptopropanol can adversely affect a number of essential metal-activated enzymes, such as catalase, carbonic anhydrase and peroxidase, and also produce dangerous systemic effects. Dimercaptopropanol cannot be used to remove cadmium because its cadmium complex is toxic to kidney tissue54). 

CPO may act via chelation of trivalent metal cations (e.g., Fe, for which it has a high affinity, or may act to inhibit metal-dependent enzymes (e.g., catalase/peroxidase), which participate in the intracellular degradation of peroxides resulting in an increase in ROS generation. 

Table 11. Enzymic activity of different Cu2+ and/or Zn2+ apoerythrocuprein chelates. The reciprocal concentrations of these different metal apoprotein complexes were compared under equilibrium conditions ( Cyt credl X Cyt cox]-1 = 1)- For each metal protein 4 different assays were performed. Incubations were carried out at 25°. The assay mixture was composed of xanthine, 3.3 x 10 AM beef-heart cytochrome cox, 2.7 X 10 5M catalase, 1.6 x 10 SM xanthine oxidase, 2.1 x 10 1M HEPES buffer, 5 x 10 2M, pH 7.8 (78, 122)...

A review of the possible quantitative detection of mannitol by chelation with transition metal ions is mentioned in Chapter 17, the conformation of alditols in aqueous and non-aqueous solution is reported in Chapter 21, the cryoprotective effect of mannitol and D-glucitol on the denaturation of the enzyme catalase during the freeze drying process is covered in Chapter 2, the separation of alditols by ion exchange chromatography is mentioned in Chapter 23 and the isolation from two new Streptomyces strains of some secondary metabolites of L-rhodanose is covered in... 

The co-operative effect. That a metal can become much more chemically active after chelation is evident enough in the oxygen-binding properties of haemoglobin and the oxidizing powers of the heme enzymes. Inorganic salts of iron have catalase- and peroxidase-like properties, but these are enormously increased upon incorporation in the porphyrin nucleus attached to a specific protein. Similarly, cuprous ions catalyse the aerial oxidation of ascorbic acid, but this effect is immensely magnified in the enzyme ascorbic oxidase (Table 10.4). 

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