Types of Enzymes

Enzymes are large biomolecules that are required for the numerous chemical interconversions that sustain life. Like all proteins, enzymes are long, linear chains of amino acids that fold to produce a three-dimensional product. Each unique amino acid sequence produces a specific structure, which has unique properties. Individual protein chains may sometimes group together to form a protein complex. Most enzymes can be denatured that is, unfolded and inactivated by heating or chemical denaturants, which disrupt the three-dimensional structure of the protein. Depending on the enzyme, denaturation may be reversible or irreversible.

Enzymes accelerate all the metabolic processes in the body and carry out a specific task. Enzymes are highly efficient, which can increase reaction rates by 100 million to 10 billion times faster than any normal chemical reaction. Due to development in recombinant technology and protein engineering, enzymes have evolved as an important molecule that has been widely used in different industrial and therapeutical purposes.

There are three main categories of enzymes: (1) metabolic enzymes, which are produced within the body; (2) digestive enzymes, which the body produces also; and (3) food enzymes.

Purple raspberry growing on a raspberry cane

Metabolic enzymes are responsible for running the body at the level of the blood, tissues and organs. They are required for the growth of cells and repair and maintenance of all the body's organs and tissues. Metabolic enzymes take protein, fat, and carbohydrates and transform them into the proper balance of working cells and tissues. They also remove worn-out material from the cells, keeping them clean and healthy.

Digestive enzymes aid in the digestion of food and the absorption and delivery of nutrients throughout the body. The most commonly known digestive enzymes are secreted from the pancreas into the stomach and small intestine. Each enzyme is specific to a particular compound which it breaks or synthesizes. The 3 most important enzymes for digestion are protease, which digests protein; amylase, which digests carbohydrates; and lipase, which digests fat.

Food enzymes are derived solely from raw fruits, vegetables, and supplemental sources. Like digestive enzymes, they enable the body to digest the food by breaking down the various nutrients, such as proteins, fats, carbohydrates, and vitamins and minerals, into smallest compounds that the body can absorb. They are absolutely essential in maintaining optimal health.

Overwhelming evidence shows that food enzymes play an important role by predigesting food in the upper stomach. Supplementation of food enzymes is necessary today because so much of the food is processed or cooked. Most food enzymes are destroyed at the temperatures used to cook and process food. Food enzymes are extremely sensitive to temperatures above 118 °F. When raw foods are processed or heated in any way, they may lose 100% of their enzymes activity and up to 85% of their vitamin content. Unfortunately, even the raw food might be enzyme-deficient if it was grown in nutrient-lacking soil.


To function properly, food enzymes must also work in tandem with the coenzymes of vitamins and minerals. Unlike the enzymes in raw plant foods, coenzymes are not completely destroyed by cooking. Unless the enzymes from raw food are present, the coenzymes in the food cannot be utilized to their full potential.

For all these reasons, supplementing with enzymes is crucial to achieving a more efficient digestive process and better absorption of food's nutrients.

When an animal has an enzyme deficiency, it develops many health problems. These include digestive disturbances, constipation, gas, bloating, colon problems, excess body fat, and problems as serious as heart disease. Enzyme deficiencies have been linked to premature aging and degenerative diseases as well. In fact, studies have shown that diets deficient in enzymes can cause a 30% reduction in life span. Cancer research has discovered that certain enzymes are absent in the blood and urine of many cancer patients. Lack of enzymes and the resulting malabsorption of nutrients can also cause allergic reactions, poor healing of wounds, and skin problems.

Enzyme supplements help create more energy, promote faster and easier digestion, and encourage superior nutrient absorption. The animal's digestive system works best when enzyme supplements assist in setting the nutrients free for the body to absorb and use.

Other types of enzymes include: DNA Repair Enzymes, DNA Restriction-Modification Enzymes, DNA, Catalytic, Immobilized Enzymes, Holoenzymes, Hydrolases, Isoenzymes, Isomerases, Ligases, Lyases, Multienzyme Complexes, Oxidoreductases, Penicillin-Binding Proteins, Recombinases, Catalytic RNA, Transferases.

Classes of Enzymes

Enzymes can be grouped into functional classes that perform similar chemical reactions. Each type of enzyme within such a class is highly specific, catalyzing only a single type of reaction. Thus, hexokinase adds a phosphate group to d-glucose but ignores its optical isomer l-glucose; the blood-clotting enzyme thrombin cuts one type of blood protein between a particular arginine and its adjacent glycine and nowhere else, and so on.

There are six major classes of enzymes: Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, and Ligases.

The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze [14]. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme. Except for some of the originally studied enzymes such as pepsin, rennin, and trypsin, most enzyme names end in “ase." The common name of an enzyme usually indicates the substrate and the nature of the reaction catalyzed. For example, citrate synthase catalyzes the synthesis of citrate by a reaction between acetyl CoA and oxaloacetate.

  • Oxidoreductases (EC 1) - Catalases, Glucose oxidases, Laccases; Oxidation reactions involve the transfer of electrons from one molecule to another. In biological systems we usually see the removal of hydrogen from the substrate. Typical enzymes in this class are called dehydrogenases.. Enzymes of this type are often called oxidases, reductases, and dehydrogenases.
  • Transferases (EC 2) - Fructosyltransferases, Glucosyltransferases; remove groups (not including H) from substrates and transfer them to acceptor molecules (not including water). Aminotransferases or transaminases promote the transfer of an amino group from an amino acid to an alpha-oxoacid.
  • Hydrolases (EC 3) general term for enzymes that catalyze a hydrolytic cleavage reaction; the most frequently used enzymes in biotechnology. In general, larger molecules are broken down to smaller fragments by hydrolases.
    • Proteases - break down proteins by hydrolyzing bonds between amino acids; they remain the dominant enzyme type, because of their extensive use in the detergent and dairy industries. Amylase turns some of their starch into sugar in the mouth. The pancreas also makes amylase (alpha amylase) to hydrolyse dietary starch into disaccharides and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. Amylase has been divided into three sub classes—α- β- γ-amylase. The classification is based on the bonding type.
    • Amylases catalyses the breakdown of starch into sugars. Amylase is abundantly present in human saliva, where it begins the mechanical process of digestion.
    • Cellulases are used in industries such as the starch, textile, detergent, and baking industries.
    • Lipases perform essential roles in the digestion, transport, and processing of dietary lipids (triglycerides, fats, and oils) in most, if not all, living organisms. Some lipases are expressed secreted by pathogenic organisms during the infection (Candida albicans).
    • Mannanases are used in degrading β-Mannan polysaccharides in plant cell walls.
    • Pectinases are used extensively in various industries like wine industry; food industry; paper industry for bleaching of pulp and waste paper recycling; in the processing of fruit–vegetables, tea–coffee, animal feed; extraction of vegetable oil and scouring of plant fibres. They are important for the degradation of biomass, where pectin can comprise a significant portion of plant structure.
    • Phytases hydrolyse phytate (myo-inositol hexakisphosphate), the principal form of phosphate stored in plant seeds to produce phosphate and lower phosphorylated myo-inositols. They are used extensively in the feed industry.
    • Pullulanases are used in enzymatic conversion of starch into glucose, maltose, and fructose for use as food sweeteners.
    • Xylanases hydrolyze xylan, a major component of hemicelluloses in plant cell walls.
  • Lyases (EC 4) add or remove of groups to form double bonds (not by hydrolysis).
    • Pectate lyases are classified into different families according to their primary amino acid sequences.
    • Alpha-acetolactate decarboxylases is used in brewing of beer and fermentation step in alcohol production.
  • Isomerases (EC 5) catalyze the rearrangement of bonds within a single molecule. In other words, these enzymes change the structure of a substrate by rearranging its atoms.
    • Glucose isomerases catalyze glucose to fructose; it is produced by many organisms.
    • Epimerases catalyze carbohydrates.
    • Mutases catalyze the transfer of acyl-, phospho-, amino- or other groups from one position within a molecule to another; Chorismate Mutase catalyzes the conversion of chorismic acid to prephenic acid.
    • Lyases catalyze the cleavage of C-C, C-O, and C-N, and other bonds by other means than by hydrolysis or oxidation.
    • Topoisomerases are a class of enzymes involved in DNA manipulation.
  • Ligases (EC 6) - Ligases join molecules together with covalent bonds. These enzymes participate in biosynthetic reactions where new groups of bonds are formed. Such reactions require the input of energy in the form of cofactors such as ATP.
    • Argininosuccinate is an enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease argininosuccinic aciduria in man.
    • Glutathione synthase catalyzes the synthesis of glutathione from gamma-glutamylcysteine and glycine in the presence of ATP with the formation of ADP and orthophosphate. Glutathione synthase deficiency is a disorder that prevents the production of glutathione that helps prevent damage to cells by neutralizing harmful molecules generated during energy production. Glutathione also plays a role in processing medications and carcinogens.

ATPases hydrolyze ATP. Many proteins with a wide range of roles have an energy-harnessing ATPase activity as part of their function, for example, motor proteins such as myosin and membrane transport proteins such as the sodium–potassium pump.

Kinases catalyze the addition of phosphate groups to molecules. Protein kinases are an important group of kinases that attach phosphate groups to proteins.

Nucleases break down nucleic acids by hydrolyzing bonds between nucleotides.

Phosphatases catalyze the hydrolytic removal of a phosphate group from a molecule.

Polymerases catalyze polymerization reactions such as the synthesis of DNA and RNA.


  1. A Broader View: Microbial Enzymes and Their Relevance in Industries, Medicine, and Beyond
  2. A Broader View: Microbial Enzymes and Their Relevance in Industries, Medicine, and Beyond. Neelam Gurung, 1 Sumanta Ray, 1 Sutapa Bose, 1 ,* and Vivek Rai 2 ,* Biomed Res Intv.2013; 2013
  3. Enzymes: principles and biotechnological applications. Peter K. Robinson Portland Press Opt2Pay



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