Mechanism chemical conjugation

Specifying the chemical conjugation mechanism, it should be noted that in this case a final product is formed in the overall reaction which acts as a reagent-inducer in the system and with the help of which active particles necessary for speeding up the secondary reaction are generated in the system. 

It is shown that low-temperature liquid-phase oxidation of resinous acids, their salts and dicarboxylic acids, as well as their mixtures with hydrocarbons is accompanied by decarboxylation, the latter not proceeding in the absence of oxidation. The chemical conjugation mechanism in decarboxylation becomes of importance, associated with the production of fatty acids and organics oxidation. 

To demonstrate, the chemical conjugation mechanism may be presented by the following generalized scheme ... 

As mentioned in Chapter 2, chemical conjugation is absent in initiated processes. Moreover, initiated parallel chain processes (3.29) and (3.30) display the main reaction paths for reagent transformation to final products no matter what the manner of initiation. As shown by scheme (3.28), at chemical conjugation the first stage of the primary process in the mechanism and material balance equation must be taken into account by both reactions. 

Since biochemists clearly understood that H+ ion was involved in oxidative phosphorylation, the alternative ATP formation concept occurred as a counter to chemical conjugation. This concept was called the chemiosmotic hypothesis of the oxidative phosphorylation mechanism. This hypothesis was developed by Mitchell, the famous English biochemist [20], who turned is attention to the blind sides of the chemical conjugation concept. 

Thus, transport of highly active intermediate product through a membrane is the necessary condition for conjugation on membrane catalysts. Moreover, understanding of the conjugation mechanism requires the reaction system to be considered as the entire system divided by a membrane into two parts. In its turn, the membrane must display catalyst properties on both sides. Specific features of catalysis on membrane catalysts allow the promotion of effective chemical conjugation. 

To accompany the similarity of chemical and biochemical processes proceeding with membrane catalysts, let us also indicate their specific features, which show the elegancy of Nature s modernization of the chemical conjugation mechanism. 

Highly active intermediate substance, generated in the primary reaction, is always consumed for conjugated reaction product synthesis, and the higher its induction effect on the secondary reaction, the lower its consumption in the primary reaction. It follows that if products of both reactions are of great importance for consecutive biochemical reactions, in this case of chemical conjugation, in principle, the maximum effect is improbable. This gives rise to the question of whether any additional mechanism may be used to provide for effectiveness in both directions. 

The above idea may be related to the interpretation of the conjugation mechanism of biooxidation reactions proceeding on the surface of mitochondrial membrane. It is known that Nature always displays great efficiency and rationality in the organization of biochemical processes. It is, therefore, no wonder that the same properties are observed in the structural organization of chemical conjugation, on which cell bioenergetics is based. 

Figure 3.5 The mechanism of chemical conjugation in mitochondrial energy process.

Nature suggests to us an idea to modernize already known and newly discovered catalytic reactions via chemical conjugation mechanism. In general, the task may be formulated as follows ... 

Of course, the above list gives only the most important cases. What is obvious is that the prospective combination of catalysis and chemical conjugation methods will give a new direction for the selective transformation of substances by the oxidation mechanism. 

In this connection, it should be expected that the application of chemical conjugation will allow oxidation of methane to formaldehyde with hydrogen peroxide according to a new reaction mechanism. 

Thus, taken together, the theoretical and experimental studies carried out lead to a new, chemically particularized mechanism of conjugated dehydrogenation, which consists of the primary (induction) reaction of H202 dissociation and the secondary (inducible) reaction of conjugated dehydrogenation. 

As a result of these investigations, the most probable mechanism was suggested. According to this mechanism, H202 dissociation and methane oxidation (5.27) reactions are chemically conjugated via general intermediates - OH and H02 free radicals. 

In the context of the above, the authors suggest that consideration of catalase and non-classical peroxidase reactions from positions of the ability of H202 to induce chemical conjugation in oxidation reactions broadens our knowledge about the role and mechanism of catalases and peroxidases. 

The catalytic activity for a synthesized mimic [24] was also estimated by the number of catalytic cycles in two chemically conjugated reactions. Data in Table 7.2 show that, being the analog of active site of natural protein, iron protoporphyrin manifests 2 times lower activity. Resistance to the effects of oxidants and their intermediates is also higher for natural protein, because corresponded mechanisms can barely be simulated in the mimic. 

The mechanism of such mimics is discussed in detail in the literature [1], It is indicated that monooxygenase, including epoxidation, are conjugated with the catalase process. The mandatory parameter of chemical conjugation in such chemical systems is the determinant value, calculated by the following equation ... 

Thus, the studied mimic catalyzes two interrelated, chemically conjugated catalase and monooxygenase reactions. The conjugation mechanism is comprehensively described by the following diagrams [11] ... 

Additional sufficient capabilities also occur as a result of the chemical conjugation mechanism, on which the overwhelming majority of enzymatic reactions are based. There is a firm belief that, in principle, a sequence of conjugated chemical processes can be selected for any reagent, starting from the substance to be detected and ending with an active product of enzymatic reaction. To put it another way, the corresponding enzymatic electrode may always be prepared. 

It is apparent that in future a combination of catalysis and chemical conjugation will be an important direction in the search for ways of selective substance transformation according to the oxidative mechanism. 

From the very beginning, it was clear that the reaction system of two or more synchronous reactions will always find conditions and factors promoting their interaction. The level of our knowledge about kinetics and the mechanism of chemical reactions did not allow interpretation of the majority of interactions between reactions in the framework of the old concept of chemical conjugation. This prompted the question of creating a new concept which would unambiguously determine a complex interaction (coherence) between synchronous reactions. 

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