Catalase reactions

With some products, particularly snap beans, there may be some reason to question the validity of a negative catalase reaction as a criterion of adequate blanching, especially in the light of the work reported by Bedford and Joslyn (3). In the case of peas, however, it seems to be entirely adequate. There is urgent need for investigation and the development of an adequate method for testing adequacy of blanching in finished products. 

Ogura, Y. and Yamazaki, I. (1983). Steady-state kinetics of the catalase reaction in the presence of cyanide. J. Biochem. (Tokyo) 94, 403-408. 

The prepolymer used for this study was an MDI-based preparation (Suprasec 1002) from Huntsman PU, Brussels, Belgium. Immobilization of the enzyme was accomplished by coating the inside structure of a reticulated foam with an acetone solution of a hydrophilic polyurethane prepolymer. A 45-pore/in. reticulated foam cut into sheets 0.25 in. thick was used. The coated reticulated foam was immersed in a catalase solution (5 pg/ml) at 4°C and left in the solution for 1 hour to ensure a complete solution. It is known that both the water and some functionality in the catalase react with the isocyanate groups to cause polymerization (the water-isocyanate reaction) and chain termination (the catalase reaction). Controlling the relative concentrations and temperature permits control of the physical properties of the composite and the ability of the foam to function as an enzyme. 

Another possible back-reaction to the resting state is realized in the function of the catalases (path D in Scheme 2.11) and therefore denoted catalase reaction . 

In fact, the a-ketoglutarate/glutamate dehydrogenase is a generally applicable method for the regeneration of NAD and NADP in laboratory scale productions. Both components involved are inexpensive and stable. Quite recently, a method for the oxidation of the reduced nicotinamide coenzymes based on bacterial NAD(P)H oxidase has been described [225], This enzyme oxidizes NADH as well as NADPH with low Km values. The product of this reaction is peroxide, which tends to deactivate enzymes, but it can be destroyed simultaneously by addition of catalase. The irreversible peroxide/catalase reaction favours the ADH catalyzed oxidation reaction, and complete conversions of this reaction type are described. 

The history of the development of physical chemistry for enzymatic processes and composition of their chemical models shows that the foundation was laid in the works studying catalase reactions. Catalase enzyme is present in all aerobic organisms and catalyzes dissociation H202, toxic for living cells [31]. 

Critically analyzing the mechanism (6.8)-(6.12), one may note the unsuitability of the currently presented interaction between complexes E-Fe3+—OH and E-Fe3+ OOH and substrates (H202 and H2D), because it is unclear how the substrate is activated. Moreover, intensification of the catalase reaction induces a non-classical peroxidase activity increase in ethanol and formic acid oxidation reactions. This indicates the existence of a unit common to these two processes [82, 83], The alternative action of catalase (catalase of peroxidase reaction) in the biosystem with solidarity of elementary stage mechanisms should be noted [88, 89], Peroxidase action of catalase requires a continuous supply of H202 for ethanol and formic acid oxidation, which can be explained by oxidation according to conjugated mechanism [90],... 

Studies of hematin associates [94] indicate their inactivity in the catalase reaction. The interaction by the Fe-O-Fe mechanism, the existence of which was confirmed by the Mossbauer spectroscopy method, also disproves the idea of two hematin group interaction in the active site of catalase [92],... 

In the course of developing the idea of the enzymatic catalysis mechanism Poltorak [99] stated the uniformity of enzymatic catalysis mechanisms in the framework of suggested notion of linear chain of bond redistribution (linear CBR). Actually, this idea laid the foundation for the catalase reaction mechanism suggested by Poltorak. In this mechanism, owing to composition of linear CBRs he showed the means for effective proton transfer between... 

Further reduction of the catalase complex VI is shown in Figure 6.5 (peroxidase reaction) and Figure 6.6 (catalase reaction). These diagrams show that peroxidase and catalase reactions of catalase proceed by two-electron transfer mechanism in one stage and are practically equal. 

According to Rossmann, the C2H5OOH molecule is converted to one CH3CHO molecule and H20, whereas a catalase reaction requires two H202 molecules for H20 and 02 synthesis. Thus, ethanol produced in complex V synthesis is immediately oxidized to aldehydes. In the analysis of both reactions of special attention is the circumstance that in a stoichiometric aspect, the Rossmann reaction represents dehydrogenation ... 

Figure 6.11 The formation mechanism of catalase reaction products, (a) The Oguri complex formed with the second H2Q molecule, (b) H20 and 02 formation, and native enzyme synthesis.

The lifetime of the complex is several minutes therefore, it is doubtful that such a relatively stable intermediate product can provide for such a high catalase reaction rate. 

If the diagram is analyzed in the context of the principles of conjugated reaction, it may be concluded that conjugated biooxidation with hydrogen peroxide consists of the basic (primary) catalase reaction of H202 dissociation (reaction (6.17)). Owing to the Chance complex formation [116, 117], this primary reaction induces the secondary non-classical peroxidase reaction (6.18). 

An analogous diagram is presented by Kremer [118], where catalase and peroxidase reactions are considered to be competitive processes. The statement about competition between these reactions eliminates the possibility of peroxidase reaction speeding up by means of catalase reaction intensification. 

Meanwhile, the data obtained [87, 116] unambiguously indicate that the catalase activity increase is associated with non-classical peroxidase activity intensification. It is obvious that the last circumstance casts some suspicion on the interpretation of reactions (6.17) and (6.18) as the competing ones, because in this case, intensification of one reaction should cause suppression of the other. Moreover, as follows from Kremer s data [118], the catalase reaction rate is five orders of magnitude higher than the peroxidase reaction rate. Therefore, comparison of these reactions from competition positions is very suspect. An article by Chance and coworkers [119] can be mentioned as evidence that a H202 concentration increase in the system in the presence of ethanol intensifies peroxidase activity (hence, intensification of the catalase activity is implied). Because catalase activity increase causes the Chance complex formation at higher rate, the peroxidase reaction (6.18) rate is also increased owing to chemical induction principle. 

If only hemin or adsorbent (A1203 or Si02) affects aqueous hydrogen peroxide, at room temperature catalase reaction is not practically observed. 

It is shown that with the model system [38, 59] heme iron reaction with hydrogen peroxide is promoted by acidic catalytic sites, which are replaced by distal amino acid group bound to heme [60], Here experimentally observed two-electron oxidation substrate in one stage and corresponded hydride-ion transfer is confirmed [61, 62], In the example of catalase reaction the transfer mechanism of two electrons simultaneously was discussed above... 

Slightly different models of catalase and H202 and ROOH disproportionation are discussed by Traylor and Xu [64], Based on an analysis of the literature and his own data, he concludes that the main stages of model catalase reactions are the following ... 

Figure 7.8 shows the principles of PPFe3+0H/Al203 H202 complex formation in accordance with the BRC theory for catalase reaction [77-79], In these works, A1203 is used as the matrix of the acidic-basic origin. 

The presence of maxima on the curves is explained as follows. If the ratio S H202 is below 1 1.5, H202 concentration in the reaction mixture increases, which intensifies primary catalase reaction (7.7). A significant amount of general intermediate of conjugated reactions (7.7) and (7.8) is consumed in the first of them. As a consequence, the induction effect of this process on epoxidation is reduced. 

For the purpose of studying the effect of the inorganic matrix origin on iron protoporphyrin biomimic activity in methane oxidation to methanol the above-mentioned carriers of the acidic-basic type were used. According to data in Tables 7.4 and 7.5, mimics derived from them simultaneously simulate catalase reaction and monooxygenase function of cytochrome P-450. 

The overall reactions (7.13) and (7.15) are implemented via general intermediate PPFe3+ OOH/AlSiMg, which is the transmitter of the induction action of the primary (catalase) reaction on the secondary (monooxygenase) one. The determinant equation ... 

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. 

The change of electrode potential (E) of the catalase reaction with time was measured by a voltmeter. pH and E values for aqueous hydrogen peroxide were determined simultaneously for possible correlations between pH metric and potentiometric results of enzymatic activity of catalase-biomimetic sensors. The electrochemical unit was also equipped with a magnetic mixer. 

A definite quantity of oxygen molecules accumulated on the surface of the biomimetic electrode (catalase reaction) must diffuse to the volume of the adhesive layer, toward the electrode surface. Hence, the specific requirements to the adhesive follow on the one hand, it must provide strong enough adhesion of a mimic to electrode on the other hand, it must possess low oxygen adsorption ability. 

The adhesive must be highly inert in the catalase reaction. 

In all Figures electrochemical potentials possess clear maxima and minima. Such curve shapes conform to the shape for catalase and electrochemical reactions in the diffusion zone of the system. As mentioned above, molecular oxygen accumulated on the surface of the mimetic electrode during catalase reaction (8.1) diffuses through the adhesive and mimic layers to the electrode surface, where it is activated and interacts with H+. Anions OFT formed in this process may set the electrode surface free for the next portion of oxygen by diffusion only. Thus, the rate of electrochemical reaction (8.2) will be defined by the ratio of the rates of molecular oxygen diffusion to the electrode surface and reverse diffusion of OH- anions from the surface. 

As might be expected [7, 8], the curve of the electrochemical potential of the catalase reaction in relation to the water potential shifts to positive values. 

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