Fundamentals of Biochemical Engineering Part 1 - Bailey J., Ollis D. 1989

Applications of enzyme-catalyzed reactions

In this chapter, we will explore some Structure/179.html">Practical Applications OF Enzymes and investigate various types and Methods FOR PRODUCING immobilized enzyme catalysts, which enable The Use of enzymatic reactions in continuous processes. Since the kinetic parameters of such biocatalysts depend on both mass transfer and The Nature of the Chemical Reactions, it is crucial to understand the combined influence of these two factors on the catalyst properties.

All enzymes used in practical applications are obtained from natural sources (Table 4.1). Although enzymes are synthesized in every living Cell, it is usually more practical to isolate a specific enzyme from only one source—be it a plant, animal, or microorganism. Some enzymes, for instance, are produced exclusively in animal organisms. However, enzymes isolated from animals can be relatively expensive, such as rennin from calf Stomach, and their availability may depend, for example, on the demand for beef or lamb. The isolation of plant enzymes (e.g., Papain from papaya) is generally simpler, but the availability of the raw material also depends on the demand for these food products. Methods for obtaining microbial enzymes allow for easy scaling up of production. As will be shown later in Chapter 6, Recombinant DNA technology offers a novel method for producing A wide variety of enzymes (including those not normally synthesized by microorganisms or permanent cell lines) using Bacteria, Yeasts, and cell cultures. Furthermore, due to the rapid self-reproduction of microorganisms compared to plants and animals, microbiological processes are much easier to adapt to fluctuations in enzyme demand. On the other hand, enzymes used in The production of food products or Pharmaceuticals can only be produced using demonstrably safe microorganisms.

Class="center">Table 4.1. Examples of Enzymes Used in Industry^а

^а From: Arima K., Microbial Enzyme Production, in Global Impacts of Applied Microbiology, Starr M. P. (ed.), pp. 278–279, John Wiley and Sons, Inc., New York, 1964.

Although all enzymes currently used are obtained from natural sources, in this chapter, we will focus on the use of enzymes only outside of living organisms. All biological catalysts are divided into two categories: extracellular and intracellular enzymes. The first category includes enzymes secreted by The Cell into the environment, where they break down nutrient polymeric substances into low-molecular-weight compounds that can enter the cell through The Cell wall. Intracellular enzymes are normally concentrated within the cell volume and are not transported into the environment; for their isolation, Cells must be disintegrated by grinding, crushing, lysis, or some other method.

For some enzyme applications, relatively pure preparations are required. For example, glucose oxidase used for desugaring eggs (in egg powder production) must not contain Proteolytic Enzymes, and proteases injected intramuscularly into livestock before slaughter for meat tenderization must not contain any compounds that could cause a strong physiological reaction. Relatively pure enzymes are used in clinical Diagnostics and in processes related to food production and Processing.

The Kinetics of Enzymatic reactions have generally been studied using the purest enzyme preparations. As we noted in Chapter 3, such studies also employed a minimal number of substrates (preferably one, if possible) and strictly controlled environmental parameters regarding the content of activators (Ca²⁺, Mg²⁺, etc.), Cofactors, and inhibitors. The results of these studies most reliably reflect The kinetics of enzymatic reactions.

At the same time, many INDUSTRIAL ENZYME PREPARATIONS are purified to a much lesser extent. Typically, they contain a range of enzymes with diverse catalytic properties. Furthermore, in most cases, these preparations are used to treat Materials that do not even remotely resemble the pure substrates or precisely defined synthetic media discussed in Chapter 3. It should be noted that the simultaneous action of several Enzymes can be more effective than sequential Treatment with a series of individual enzymes. Despite all these complexities, such enzyme preparations are still kinetically much simpler than the intact living organisms from which they were isolated. In this regard, it seems appropriate to first consider industrial enzyme preparations, and then proceed to analyze cellular metabolic pathways and study the industrial application of biochemical technology.