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

Applications of Enzyme-Catalyzed Reactions
Applications of Hydrolytic Enzymes

Reactions Catalyzed by hydrolytic Enzymes underpin not only obvious macroscopic processes such as food spoilage, starch liquefaction, or wastewater Treatment, but also the chemistry of fruit ripening, lysis (autolysis) of dead Cells, meat tenderization, cheese production, haze Prevention in beer, texturization of confectionery products, wound debridement, and textile desizing. This section will focus on studying the enzymes used in these and other industrial Applications, as well as their sources.

Table 4.2 presents a general Classification of the most important hydrolytic enzymes. The three main groups of Hydrolases cleave ester, glycosidic, and various nitrogen-containing bonds, respectively. A more detailed Classification of Enzymes within each of these three groups is also widely used. For our purposes, it suffices to note that, for example, some enzymes catalyze the Hydrolysis of A wide variety of glycosidic bonds, while others can only cleave a single glucose oligomer. Thus, the enzyme's name alone does not necessarily define its substrate Specificity.

It should be emphasized again that the names of most enzymes are related to the reactions they catalyze, rather than their chemical Structure*. Since there is no “one enzyme — one reaction” rule in this case, enzymes catalyzing the same reaction but isolated from different plant or animal sources will not always have the same structure, and therefore The kinetics of the corresponding reactions may also vary. It follows that the maximum reaction rate, Michaelis constant, optimal pH for stability and activity, and other enzyme properties will be determined by its nature and, consequently, its source of isolation.

Many hydrolases are compartmentalized within various Structural elements of The Cell, separated from the Cytoplasm by membranes. Evidently, such localization of hydrolases protects important cytoplasmic Biopolymers from degradation. Gram-positive Bacteria secrete numerous hydrolases into the environment. In gram-negative bacteria, the periplasmic space of the outer envelope, delimited by two membranes, serves as a reliable reservoir for various hydrolases. In Eukaryotic cells, hydrolases can be localized in membrane-bound Organelles called Lysosomes, in the periplasm (in microorganisms like Yeasts), or secreted into the environment. Most hydrolytic enzymes used in industry are extracellular products of microbial activity.

* Enzyme Classification According to the recommendations of the Enzyme Commission is provided in Table 3.1. More detailed information on enzyme classification can be found in the book: Dixon M., Webb E., Enzymes, Vol. 1—3, Ch. 5, M.: Mir, 1982.

Class="center">Table 4.2. Hydrolytic Enzymes^a

^a Weiser H. I., Practical Food Microbiology and Technology, p. 37, Avi Publishing Co., Westport, Conn., 1962.

At the same time, some hydrolases are also found in the cytoplasm. Here, they participate in metabolic cycles, thereby performing an important function by helping the cell fully utilize its internal resources. Intracellular hydrolases play a significant role in Introduction/32.html">Genetic Engineering Methods (Ch. 6).

Since Water is a universal substrate with a concentration of approximately 55 M, and because hydrolytic enzymes typically catalyze degradation reactions—for instance, The conversion of starch into sugars, proteins into polypeptides, and Lipids into glycerol, fatty acids, and phosphate—we will use various types of polymeric substrates as the basis for the subsequent Discussion. It should be noted, however, that in some recently developed methods for polypeptide synthesis in low-water environments, natural proteases have been used as condensing agents. Evidently, under specific conditions, proteases can sometimes also catalyze the reverse reaction of synthesis.