An Enzyme: Definition and Function
An enzyme is a substance that performs as a catalyst in living organisms, managing the rate at which chemical reactions proceed without being changed. The biological processes in all living organisms are chemical reactions, and enzymes regulate most. Without enzymes, many of these reactions will not occur at a perceptible rate.
Role of Enzymes in Cell Metabolism
Enzymes catalyze all aspects of cell metabolism. This includes food digestion, where large nutrient molecules (such as proteins, fats, and carbohydrates) are broken down into smaller molecules. Many inherited human diseases, such as phenylketonuria and albinism, result from a particular enzyme deficiency.
Specificity of Enzymes
As strong catalysts, enzymes also possess remarkable specificity. They usually catalyze the conversion of only one kind (or at most, a few similar types) of substrate molecules into product molecules.
Some enzymes demonstrate group specificity. For example, alkaline phosphatase, an enzyme commonly used in laboratory sessions on enzyme kinetics, can remove a phosphate group from various substrates. Other enzymes illustrate much higher specificity, portrayed as outright specificity. For example, glucose oxidase exhibits near-exclusive specificity for its substrate, β-D-glucose, and shows minimal action with other monosaccharides. This specificity is vital in numerous explanatory measures and devices, such as biosensors that measure a particular substrate (e.g., glucose) in complex combinations (e.g., blood or urine samples).
Enzymes and Their Importance
Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all chemical reactions occurring within cells. They are vital for life and serve many essential bodily functions, such as aiding digestion and metabolism.
Examples of Enzymes
- Amylase: Helps change starches into sugars.
- Maltase: Found in saliva, it breaks the sugar maltose into glucose.
- Trypsin: Found in the small intestine, breaks proteins into amino acids.
Enzymes in Industrial Processes
Enzymes are the biological substance that speeds up the rate of various biochemical responses in a living organism without being used up in the response. Enzymes are involved in most biochemical reactions in microorganisms, plants, animals, and humans. The actions of enzymes are biodegradable and specific. Even though enzymes are created inside living cells, they can also work actively in vitro, making them useful in industrial processes.
The enhancement of processed food products uses enzymes. The first successful commercial use of enzymes in food processing was in cheese-making. Now enzymes are used in brewing, baking, meat tenderization, protein hydrolysis, etc. Enzymes enhance the nutritional value and flavour of ingredients and food products.
Applications in Food Processing
Enzymes involved in food processing have an essential role. The aim is to substitute conventional and harmful chemical processes with environmentally friendly alternatives while improving products’ biodegradability and reducing energy consumption. This could open new possibilities for enzyme applications, particularly in the food-processing sector.
Digestive Enzymes
Digestive enzymes are substances that help in the digestion of food. Digestive enzymes are secreted (released) by the salivary glands and cells lining the stomach, small intestine, and pancreas. Digestive enzymes split the complex and large molecules that makeup proteins, fats, and carbohydrates into smaller ones, making it simple for the nutrients in these foods to enter the bloodstream and travel throughout the body. Digestive enzymes include amylase, maltase, lactase, lipase, sucrase, and protease.
When Are Digestive Enzymes Released?
Digestive enzymes are released when we:
- Anticipate eating
- Go through the digestive process
- Smell and taste food
Specific digestive enzymes are needed to digest unique nutrients in some foods. Digestive enzyme deficits can be caused by various medical conditions, particularly those affecting the pancreas, as the pancreas produces numerous necessary enzymes.
Functions of Digestive Enzymes
Naturally occurring digestive enzymes are proteins your body makes to aid digestion and break down food. Digestion involves utilizing the nutrients in food eaten to give your body energy, which helps its growth and vital functions. Your stomach, small intestine, and pancreas make digestive enzymes, with the pancreas being the enzyme “powerhouse” of digestion.
Classes/Types of Enzymes
There are six classes of enzymes based on the types of reaction catalyzed:
- Oxidoreductases: Involved in oxidation and reduction, e.g., lactate dehydrogenase and alcohol dehydrogenase.
- Transferases: Catalyze the transfer of a particular group from one substrate to another, e.g., hexokinase.
- Hydrolases: Facilitate hydrolysis, e.g., trypsin.
- Lyases: Facilitate the removal of small molecules from a large substrate, e.g., fumarase.
- Isomerases: Involved in the isomerization of substrates, e.g., triose phosphate isomerase.
- Ligases: Join two substrates, e.g., DNA ligases.
Functions of Enzymes in Vital Processes
Enzymes support many vital processes, including:
- DNA replication: Assist in unwinding DNA coils during cell division.
- Digestion: Break down large molecules into smaller ones for energy.
- Liver enzymes: Help the liver break down toxins.
- Other activities: Respiration, hormone production, signal transduction, and more.
Health Conditions Related to Enzyme Problems
Metabolic disorders often result from inadequate specific enzymes. Parents can pass them on to their children through genes. Examples include:
- Fabry disease: Prevents the body from making enzymes to break down fat.
- Maple syrup urine disease: Affects enzymes that break down certain amino acids.
- Krabbe disease: Affects enzymes needed for the protective covering on nerve cells.
Other conditions include lactose intolerance, Crohn’s disease, and exocrine pancreatic insufficiency.
Conclusion
Enzymes have both biological and chemical attributes. Their sequences and structures delineate their role in the genome and proteome of all living organisms. Many enzymes are promiscuous and perform multiple reactions, and as protein sequences evolve, enzymes can change their reaction profile. Combining bond changes and reaction centres with structural information about the substrates, products, and mechanisms is needed to capture the essence of enzyme chemistry in a functional classification.
