Catalases properties

At the same time the interaction of superoxide with MPO may affect a total superoxide production by phagocytes. Thus, the superoxide adduct of MPO (Compound III) is probably quantitatively formed in PMA-stimulated human neutrophils [223]. Edwards and Swan [224] proposed that superoxide production regulate the respiratory burst of stimulated human neutrophils. It has also been suggested that the interaction of superoxide with HRP, MPO, and LPO resulted in the formation of Compound III by a two-step reaction [225]. Superoxide is able to react relatively rapidly with peroxidases and their catalytic intermediates. For example, the rate constant for reaction of superoxide with Fe(III)MPO is equal to 1.1-2.1 x 1061 mol 1 s 1 [226], and the rate constants for the reactions of Oi and HOO with HRP Compound I are equal to 1.6 x 106 and 2.2 x 1081 mol-1 s-1, respectively [227]. Thus, peroxidases may change their functions, from acting as prooxidant enzymes and the catalysts of free radical processes, and acquire antioxidant catalase properties as shown for HRP [228] and MPO [229]. In this case catalase activity depends on the two-electron oxidation of hydrogen peroxide by Compound I. 

Cook, A. H. Catalytic Properties of the Phthalocyanines. Part. I. Catalase Properties. 

The oxidase reaction is inhibited by carbon monoxide and by catalase, properties which are characteristic of oxidase-peroxidases, and which suggest that both ferrous iron and hydrogen peroxide participate in the overall reaction. If this is the case, inhibition by catalase may be explained by (1) destruction of hydrogen peroxide necessary to initiate the formation of ferroperoxidase, corresponding to the reduction of ferricatalase to ferrocatalase in the presence of peroxide and an electron donor (752), ) a side reaction in which oxyferroperoxidase is reduced to ferriperoxidase via Complex II (compare Fig. 17), or (S) destruction of peroxidase. In support of the last alternative, it has been observed that the decomposition of peroxide-... 

As a result of the micellar environment, enzymes and proteins acquire novel conformational and/or dynamic properties, which has led to an interesting research perspective from both the biophysical and the biotechnological points of view [173-175], From the comparison of some properties of catalase and horseradish peroxidase solubilized in wa-ter/AOT/n-heptane microemulsions with those in an aqueous solution of AOT it was ascertained that the secondary structure of catalase significantly changes in the presence of an aqueous micellar solution of AOT, whereas in AOT/n-heptane reverse micelles it does not change. On the other hand, AOT has no effect on horseradish peroxidase in aqueous solution, whereas slight changes in the secondary structure of horseradish peroxidase in AOT/n-heptane reverse micelles occur [176],... 

Acatalasemia is a rare hereditary deficiency of tissue catalase and is inherited as an autosomal recessive trait (03). This enzyme deficiency was discovered in 1948 by Takahara and Miyamoto (Tl). Two different types of acatalasemia can be distinguished clinically and biochemically. The severe form, Japanese-type acatalasemia, is characterized by nearly total loss of catalase activity in the red blood cells and is often associated with an ulcerating lesion of the oral cavity. The asymptomatic Swiss-type acatalasemia is characterized by residual catalase activity with aberrant biochemical properties. In four unrelated families with Japanese-type acatalasemia, a splicing mutation due to a G-to-A transition at the fifth nucleotide in intron 4 was elucidated (K20, W5). We have also determined a single base deletion resulting in the frameshift and premature translational termination in the Japanese patient (HI6). 

Depending on the immobilization procedure the enzyme microenvironment can also be modified significantly and the biocatalyst properties such as selectivity, pH and temperature dependence may be altered for the better or the worse. Mass-transfer limitations should also be accounted for particularly when the increase in the local concentration of the reaction product can be harmful to the enzyme activity. For instance H2O2, the reaction product of the enzyme glucose oxidase, is able to deactivate it. Operationally, this problem can be overcome sometimes by co-immobilizing a second enzyme able to decompose such product (e.g. catalase to destroy H202). 

Turning to l-AAO, Pantaleone s industrial research group have reported" on the properties and use of an l-AAO from Proteus myxofaciens, overexpressed in Escherichia coli This l-AAO, unusually, appears not to produce H2O2 in the catalytic reaction, thus making the addition of catalase unnecessary. The enzyme has a broad specificity, with a preference for nonpolar amino acids. This l-AAO was used in conjunction with a D-amino acid transaminase (d-AAT) and an alanine racemase (AR) to allow an efficient conversion of L-amino acid in to D-amino acid (Scheme 4). 

Frew JE, Jones P (1984) Structure and fimctional properties of peroxidases and catalases. In Sykes G (ed) Advances in inorganic and bioinorganic mechanisms. Academic Press, New York, p 175... 

Within this common core structure, modifications have been identified that provide catalases with further unique properties. The large-subunit enzymes have extensions at both the amino and carboxyl ends, the latter having a flavodoxinlike structure, a unique His-Tyr bond, a protected cysteine, and a modified heme. NADPH binding and an oxidized methionine are found in small subunit enzymes. Identification and assignment of roles to channels providing access to and egress from the deeply buried heme have recently become the focus of study. Analysis of the structure of catalase HPII of E. coli has been facilitated by the construction of more than 75 mutants (Table I). 

The increase in levels of tissue CAT is compatible with previous results which showed that LLLT induced an increase in CAT activity of irradiated isolated cardio-myocytes compared to controls. It was suggested that laser therapy efficacy in chronic wounds and ulcers can be attributed to the activation of CAT in tissue fluids [62]. He-Ne laser has been shown to cause photoactivation and structural modifications of catalase enzymes that positively correlated with its functional properties in cell free system [63]. 

Aryukhov G, Basharina O, Pantak A, Sveklo L (2000) Effect of hehum-neon laser on activity and optical properties of catalase. Biull Eksp Biol Med (Moscow) 129(6) 633-636... 

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