Kinetics of Enzymes and Models

This chapter solely reviews tlie kinetics of enzyme reactions, modeling, and simulation of biochemical reactions and scale-up of bioreactors. More comprehensive treatments of biochemical reactions, modeling, and simulation are provided by Bailey and Ollis [2], Bungay [3], Sinclair and Kristiansen [4], Volesky and Votruba [5], and Ingham et al. [6]. 

Part II of this book represents the bulk of the material on the analysis and modeling of biochemical systems. Concepts covered include biochemical reaction kinetics and kinetics of enzyme-mediated reactions simulation and analysis of biochemical systems including non-equilibrium open systems, metabolic networks, and phosphorylation cascades transport processes including membrane transport and electrophysiological systems. Part III covers the specialized topics of spatially distributed transport modeling and blood-tissue solute exchange, constraint-based analysis of large-scale biochemical networks, protein-protein interactions, and stochastic systems. 

The basis of the operational model is the experimental finding that the experimentally obtained relationship between agonist-induced response and agonist concentration resembles a model of enzyme function presented in 1913 by Louis Michaelis and Maude L. Menten. This model accounts for the fact that the kinetics of enzyme reactions differ significantly from the kinetics of conventional chemical reactions. It describes the reaction of a substrate with an enzyme as an equation of the form reaction velocity = (maximal velocity of the reaction x substrate concentration)/(concentration of substrate A a... 

As in all PK models described in this chapter, the rate of drug elimination is taken to follow first-order (or linear) elimination kinetics. Thus the rate of elimination is proportional to the amount of drug remaining to be eliminated. As discussed previously, this is often a reasonable approximation as most drug concentrations in the body are much less than the Michaelis-Menten value of enzymes and transporter proteins. 

A particularly useful model for the kinetics of enzyme-catalyzed reactions was devised in 1913 by Leonor Michaelis and Maud Menten. It is stiU the basic model for nonallosteric enzymes and is widely used, even though it has undergone many modifications. 

Structural studies of both types of enzyme have been extensive, and in the case of the heme NiRs a considerable body of kinetic data has been reported. Reviews of these enzymes and model coordination compounds relevant to substrate binding and reactivity have been published. - ... 

The kinetics of soluble and immobilized enzymes. Involved In reactions of soluble and Insoluble substrates appears to be sufficiently well studied over the last 20 years that reactor design procedures based on fundamental kinetics rate equations may be executed with considerable confidence. The application of such emzyme kinetics forms to structured models of microbial metabolism has also progressed, as this book documents. 

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