Multienzyme process modeling

For a multienzyme process, this evaluation is critically important to achieve a better theoretical understanding of the process and to achieve useful modeling and process design. The reaction considerations describe the key characteristics to understand how the interaction between enzymes and components can be interpreted for modehng. Furthermore, such information forms the basis for the formulation of reaction rates for the different enzymes that are involved in multienzyme process. In this manner, a preliminary idea of enzyme mechanisms and kinetic parameters, that can be expected when developing a model, may be obtained. Key information (Figure 10.3) may be described as... 

Structure of the reaction a graphical identification of aU reactions in the multienzyme process is the basis for describing the final model structure. It includes the... 

Figure 10.3 Considerations for process modeling and design of multienzyme systems. (Santacoloma, P.A. 2012 [41], Thesis. Reproduced with permission of the Technical University of Denmark, Lyngby/Denmark.)...

Process control in multienzyme processes, variables such as pH and temperature are often controlled during the process in order to reduce the influence that they produce on the dynamics of other variables and enzymes. For modeling, the controlled variables need to be identified in order to limit the capabilities of the model. In this case, they are included as assumptions of the model. Process control can be divided into two basic control layers [43]. The first is known as the regulatory layer, which controls variables such as pH and temperature. In this case, a simple controller design can be implemented. The second is known as the supervisory layer, which manages variables with more impact on the process such as concentrations of the compounds. In this case, a more detailed controller design is required. For multienzyme processes, this issue is highly relevant especially to achieve process improvements. 

Cascade architecture A graphical representation of all reactions in the mulhen-zyme process is the basis for describing the final model structure. It includes the primary reachons, secondary reactions, and competing reactions. For a single enzyme, reachon mechanisms are well developed, and they are then included into the full model to describe the multienzyme process by combining the effect of the individual enzymes. In this way, the different possible reaction schemes are generated to give the cascade structure. 

A multienzyme complex simultaneously carries out both leading and lagging strand replication. You can see the best model of the process in the next figure the lagging strand may curl around so it presents the correct face to the enzyme. The two replication forks proceed around the chromosome, until they meet at the terminus. Termination is poorly defined biochemically, but it is known to require some form of DNA gyrase activity. See Figure 8-12. 

Entrapment of Candida tropical is whole cells in ionic polymeric networks has been achieved using different types of polyelectrolyte polymers (alginates, carbomethylcellulose, synthetic maleic acid copolymers) and multivalent counterions (e.g.. Ar ). Oxidative degradation of phenol served as a model reaction for a multienzyme catalytic process. 

Fig. 67. Model of fatty acid synthetase. In the center of the multienzyme complex is the acyl carrier protein with its pantetheine arm which is shown again in detail below. The arm wheels around from one enzyme of the complex to the next in the direction of the arrow. In the process the individual reactions of chain elongation take place, reactions which are marked with the same letters as in Figure 66 (modified from Lynen 1969).

Use of Coimmobilized Multienzyme Systems as Models for in Vivo Processes Marlene DeLuca... 

In all of the multistep immobilized enzyme work done to date, theoretical or experimental, for modelling purposes or for applications, there exists one common factor the chemical reactions are affected by the diffusive processes so that the macroscopically observed kinetics are strongly perturbed by the incorporation of the enzymes into a gel. This perturbation is caused by the development of localized concentrations and concentration gradients within the gel which are quite different from that found in free solution. Only one instance appears to have been reported where exact modelling of real experimental data has been attempted. All other work has been either purely theoretical or qualitative interpretations of limited experimental data. There is still much to be learned of the role played by the gel matrix in affecting the overall kinetic performance of gel entrapped multienzyme systems before they can be well designed for applications or used with any confidence in a quantitative way as models for living systems. 

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