Catalysis is a term that describes a process in which the rate and/or outcome of a reaction are influenced by the presence of a substance called the catalyst that is not consumed during the reaction and is then removed if it is not to become an impurity in the final product.
What is Biocatalysis?
Biocatalysis uses natural substances such as enzymes from biological sources or whole cells to speed up chemical reactions. They provide high yield and purity while being inexpensive. Biocatalysts have some advantages over chemical synthesis methods. More importantly, all biochemical reactions in living organisms rely on catalysts.
Enzymes have a high degree of chemoselectivity, regioselectivity, and stereoselectivity. They play a critical role in the catalysis of hundreds of reactions, including the fermentation of alcohols and the production of cheese from the breakdown of milk proteins.
Types of Biocatalysts
Biocatalysts can be divided into 6 types:
- Oxidoreductases are enzymes that participate in oxidation-reduction reactions.
- Transferases are enzymes that catalyse functional group transfer.
- Hydrolases are enzymes that catalyse the hydrolysis of various compounds.
- Lyases are enzymes that specialise in adding or removing water, ammonia, CO2, and other substances.
- Isomerases are enzymes that participate in all isomerisation reactions.
- Ligases are enzymes that catalyse the synthetic reactions in which two molecules are joined, and ATP is used.
Catalase and glucose oxidase are examples of oxidoreductases. Glucosyltransferases are an example of transferases. Amylases, proteases, lipases, cellulases, pectinases, and phytases are all hydrolases. The other three types, which contain enzymes, such as pectate lyases and glucose isomerases, are less common.
Role of Enzymes as Catalysts
A biocatalyst can be the entire cell in a viable, non-viable, growing, or non-growing state or an individual enzyme. A natural enzyme is a biological macromolecule produced by living organisms. It is mostly made up of proteins. These are complex nitrogenous proteins that help in the catalysis of biochemical reactions in living organisms. Enzyme catalysts catalyse chemical reactions (and energetic transformations) in a single cell or throughout an organism, which are necessary for survival and reproduction. They increase the rate at which equilibrium is reached without changing the equilibrium constant by providing an alternative reaction path with lower activation energy than the corresponding un-catalysed reaction.
Characteristics of Biocatalysts
- Most known chemical reactions are catalysed very efficiently with the help of biocatalysts.
- High stereo and regioselectivity.
- Low energy consumption due to mild reaction conditions.
- The amount of byproducts is minimal.
- They degrade naturally.
- Fermentation allows for large-scale preparation (microbial enzymes).
- They can be designed to some extent for reuse (immobilisation) and are non-toxic when used correctly.
Applications of Biocatalysts
As an alternative to chemical catalysis, biocatalysis has found numerous applications in a variety of fields. The use of enzymes in organic synthesis, particularly in producing chiral compounds for pharmaceuticals and the flavour and fragrance industry, is one of the most prominent examples. Furthermore, biocatalysts are widely used to produce speciality and even bulk chemicals. Biocatalyst also finds its application in the following industries:
- Textile industry
- Detergent biocatalyst
- Biocatalyst to convert sugars from starch
- Production of biodiesel
- Waste management
- Food industry
Biocatalysis has matured and become a widely used technology over the last two decades. It is becoming a more widely applicable tool for chemical synthesis and manufacturing.