BIOLOGY Volume 2 - A Guide to General Biology - 2004

12. MICROBIOLOGY AND BIOTECHNOLOGY

12.16. Enzyme Technologies

In this section, we will examine how Cell-isolated Enzymes are utilized in biotechnology.

Enzymes are biological catalysts that coordinate chemical activity within Cells. Although enzymes have been used by humans for thousands of years, it was only in the late 19th century that we began to understand how they work. Today, we know that enzymes are complex protein molecules with a specific three-dimensional conformation and that their Structure is encoded in DNA. The number of possible configurations is virtually limitless.

Enzymes are attractive for industrial Applications for two main reasons. First, due to their diversity, enzymes have the potential to catalyze a multitude of industrially important Chemical Reactions. Second, they are far more efficient and specific than conventionally used inorganic catalysts. Under normal temperatures and pressures, they facilitate reactions that typically require extremely high temperatures and pressures. For instance, in one of the world's largest industrial manufacturing processes, based on the Haber process, ammonia (NH₃) is produced from gaseous nitrogen and hydrogen at a Temperature of 500 °C and high pressure. Nitrogen-fixing Bacteria are capable of synthesizing ammonia from atmospheric nitrogen and hydrogen at room temperature and normal atmospheric pressure using enzymes, with ATP serving as an energy source. If an enzyme-based technology for Ammonia Production could be successfully developed, vast amounts of energy could be conserved. Another advantage of enzymes is their Specificity, which allows for the yield of extremely pure products—a factor of paramount importance for the pharmaceutical, food, and agricultural industries.

The Use of enzymes also presents A number of disadvantages, primarily related to the instability of Proteins extracted from cells. Such proteins readily denature upon changes in temperature and pH, and under METABOLISM/18.html">The Influence of organic Solvents used in manufacturing processes. They can also be inhibited by reaction products. Other drawbacks include the high cost of enzyme isolation processes and the necessity of using "safe" (e.g., non-pathogenic) organisms, especially when the enzymes are intended for The production of animal and human feed or food. Currently, fewer than 200 enzymes are utilized out of the 2,500 that have been isolated and described (which, in turn, account for only 10% of the total number discovered in nature). The majority of enzymes are extracted from just eleven species of Fungi, four species of Yeast, and eight species of bacteria.

The future opens up broad opportunities for the engineering of novel enzymes. One such approach is the site-directed modification of individual Amino Acids by altering the genes that encode the enzymes. Our understanding of the principles governing how proteins adopt specific three-dimensional Conformations is steadily deepening, making The Emergence of entirely novel engineered enzymes in the near future quite plausible. This field is known as Protein Engineering. Furthermore, the more we learn about how enzymes function, the more likely it is that we will be able to design non-protein or partially non-protein catalysts that are significantly more stable than conventional enzymes. This avenue may well prove to be the most commercially attractive. Among the directions that promise immediate returns is the search for natural enzymes that offer a superior alternative to those currently in use. All of this demands massive investments in research and development.

Today, enzymes are employed in manufacturing processes by numerous pharmaceutical companies, cheese, beer, and wine makers, as well as producers of detergents, textiles, fruit juices, and more. Global enzyme sales currently exceed $1 billion annually. Table 12.6 provides Some data on enzyme applications.

Class="center">Table 12.6. Examples of industrial enzyme applications

12.16.1. Source of Enzymes

Microorganisms are preferred as a source of enzymes over plants or animals for the following reasons:

1) they exhibit higher growth rates;

2) they can be obtained in large quantities in fermenters under controlled conditions, making the process economically viable;

3) they carry out a wide spectrum of chemical reactions;

4) their properties can be easily improved using Introduction/32.html">Genetic Engineering techniques or through the generation of diverse mutants;

5) they have very simple nutritional requirements;

6) they are capable of growing on very inexpensive substrates, often waste products;

7) The rate of production can be adjusted according to demand;

8) they produce a multitude of extracellular enzymes that are easy to harvest and purify.