contributed by Christin B. Monroe
What do you think about when someone says “industrial chemicals”? If you’re like most people, biology is the furthest thing from your mind when you picture a vat of chemicals in a factory. You might be surprised to learn that today, many common industrial processes are performed by biological enzymes instead of traditional chemical approaches. In fact, over 500 industrial products are made with enzymes, including detergents, pharmaceuticals, and drinks.
What are enzymes?
Enzymes are biological machines that speed up chemical reactions in your body by changing their shapes temporarily. Without enzymes, life would not exist, because the reactions required would not proceed at a rate quick enough to sustain life. Some enzymes are capable of breaking down large molecules into simpler parts, while some build smaller molecules into more complex ones. The active site of an enzyme—the empty space where the components of a chemical reaction fit in—is designed in such a way that the right components slot in easily and perfectly, like a lock to a keyhole (Scheme 1).
Scheme 1. Enzymatic activity Source: Skinners’ School Biology Department
Unlike manmade machines, enzymes are proteins which can be produced by living systems using the information encoded in DNA as a template (Scheme 2).
Scheme 2. Production of proteins by DNA expression Source: http://www.katiephd.com
Why are enzymes a greener alternative to traditional chemical approaches?
Traditional chemical approaches result in challenges for large scale industrial reactions. Those challenges include:
- The need for high temperatures and pressures
- Creation of organic waste and pollutants
These reactions are typically not very efficient and often lead to the formation of unwanted side products. Enzymes represent a huge opportunity for making industrial chemical reactions more environmentally friendly.
The benefit of using enzymes to perform industrial reactions are:
- Typically operations are carried out under atmospheric conditions at room temperature and neutral pH.
- There is a lower energy demand and an increased catalytic efficiency
- Elimination of unwanted side products
- Enzymes are also biodegradable and breakdown over time.
A specific example of an enzyme used to produce the products we use in our daily lives is pectinase. Pectinase is the enzyme responsible for breaking down the compound pectin (Figure 1), the complex sugar molecule found in fruits.
Figure 1. Structure of Pectin Source: Wikimedia Commons
Pectin is a large polysaccharide, therefore it is not soluble and causes a haze or precipitation to form when fruits are squeezed for juice. If you have ever made fruit juice on a small scale you know that it can be a very messy process. Imagine the same mess on an industrial scale. By adding pectinase to the juice making process, much of the material that would jam or break machines is eliminated. Once the enzyme has done its job it breaks down and all you are left with is your desired juice product, with no harmful additives.
Where is this research going?
Naturally occurring enzymes are usually not suitable for biocatalytic processes in industry. Often whole cells are used, because the protein is unstable unless contained in the protective environment of the cell. Another challenge includes the amount of protein produced by the organism. This is due to the fact that it is difficult to force the organism to expend extra energy to make more enzyme then it needs to survive. These limitations are becoming less of an issue with advances in genetics and recombinant protein production. Another avenue is the production of proteins in organisms (other than the natural organism), where the precursor DNA for the protein is incorporated into a well-studied and manageable organism (such as Escherichia coli) that can be easily manipulated. Using this technique the enzymes can be modified at the molecular level to become more stable and ideally more efficient, as well.
With these advances in enzyme research the use of enzymes in industrial processes will be more suitable. Stay tuned for the details about one class of enzyme which is being utilized industrially in upcoming posts.
In the meantime, the next time you wash your clothes or drink a glass of apple juice, think about the enzymatic processes that have contributed to providing safer and cleaner products for your use and consumption.