What are enzymes and what is their function?
- Enzymes are naturally occurring proteins that are found in the bodies of certain living things, including humans and other animals, and that cause chemical changes such as breaking down food in the stomach.
- Within the human body, enzymes can be found in bodily fluids, such as blood, saliva, the gastric juices or the stomach and fluids in the intestines.
- In general, enzymes serve as catalysts for biological functions, including natural, involuntary bodily functions, such as blood clotting.
Enzymes have three main characteristics.
- They increase the rate of a natural chemical reaction.
- They typically only react with one specific substrate or reactant, and
- Enzyme activity is regulated and controlled within the cell through several different means, including regulation by inhibitors and activators
There are 6 major classes of enzymes found in the body. The following are the names of enzymes and their functions:
- Ligase: This enzyme in the body requires ATP and binds nucleotides together in the nucleic acids. It also binds simple sugars in polysaccarides.
- Lyase: This enzyme in the body breaks the bonds between carbon atoms or carbon nitrogen bond.
- Hydrolase: This enzyme in the body breaks large molecules into simpler molecules by adding a water molecule.
- Transferase: This enzyme in the body cuts a part of one molecule and attaches it to another molecule.
- Isomerase: The atoms in a molecule are rearranged without changing their chemical formula. This helps in getting carbohydrate molecules for certain enzymatic processes.
- Oxido-reductase: This enzyme removes hydrogen or electrons from one molecule and donates it to another molecule. This enzyme is mainly involved in mitochondrial energy production.
- Kinase: This enzyme in the body attaches a phosphate group to a high energy bond. It is a very important enzyme required for ATP production and activation of certain enzymes.
In naming enzymes, the “-ase” suffix is often appended to the name of the substrate molecule upon which which the enzyme reacts. For example, the enzyme sucrase catalyzes the transformation of the sugar sucrose in to glucose and fructose. In this case, the “sucr-” suffix represents the molecule upon which the sucrase enzyme reacts. Not all enzymes are named according to this convention.
Further on, there are 3 types of enzymes:
- Food enzymes,
- Digestive enzymes and
- Metabolic enzymes.
Keeping the important ones (for UPSC/ IAS prelims) in focus, here is the list of digestive enzymes.
Important Digestive Enzymes and their functions
Digestive enzymes are secreted by the body that helps in digestion of food. The names of enzymes that help in digestion are:
- Amylase: This enzyme helps in breaking down carbohydrates. It is found in saliva, pancreas and intestinal juices.
- Proteases: It helps in digestion of proteins. It is present in the stomach, pancreatic and intestinal juices.
- Lipases: Lipases assist in digestion of fats. It is seen in the stomach, pancreatic juice and food fats.
Breaks down carbohydrates, starches, and sugars which are prevalent in potatoes, fruits, vegetables, and many snack foods
• lactase – breaks down lactose (milk sugars)
• diastase – digests vegetable starch
• sucrase – digests complex sugars and starches
• maltase – digests disaccharides to monosaccharides (malt sugars)
• invertase – breaks down sucrose (table sugar)
• glucoamylase – breaks down starch to glucose
• alpha-glactosidase – facilitates digestion of beans, legumes, seeds,
roots, soy products, and underground stems
Breaks down proteins found in meats, nuts, eggs, and cheese
• pepsin – breaks down proteins into peptides
• peptidase – breaks down small peptide proteins to amino acids
• trypsin – derived from animal pancreas, breaks down proteins
• alpha – chymotrypsin, an animal-derived enzyme, breaks down proteins
• bromelain – derived from pineapple, breaks down a broad spectrum of proteins, has anti-inflammatory properties, effective over very wide pH range
• papain – derived from raw papaya, broad range of substrates and pH, works well breaking down small and large proteins
Breaks down fats found in most dairy products, nuts, oils, and meat