An enzyme is a biocatalyst produced by the living cell. Enzymes accelerate the biological reactions without undergoing any change themselves. They are large- sized molecules with three dimensional structure. Their specific molecular geometry and absolute specificity allows them to recognize the substrate even if it present in a complex mixture. The optimum temperature required for their function may vary.

Even before the existence of these compounds were known, man has been observing the phenomenon like souring of milk and fermentation of sugar. Early on, the preparation of cheese was discovered for which sheep and goat stomach was used- we now know that the stomach lining of these animals contains the enzyme rennet or with the sap of fig trees- which we now know to contain the enzyme ficin.

In 1874, the Danish chemist Christian Hansen prepared a pure extract of the enzyme rennet from calf stomach for industrial use. In 1933, Payen and Persoz identified the enzyme diastase which digests starch, from barley seeds.

An important function of enzymes is within the digestive systems of animals. Enzymes like amylases and proteases break down large starch or protein molecules, respectively into smaller ones, so that they can be easily absorbed by the intestines. Enzymes may work together, creating metabolic pathways. In a metabolic pathway, one enzyme uses the product of another enzyme as its substrate. Sometimes, more than one enzyme can catalyze the same reaction parallelly.

Industrial Uses of Enzymes

- Manufacture of detergents to remove proteinaceous stains
- Chill proofing of beer
- Manufacture of liquid glue
- Liquification and hydrolysis of casein, lactalbumin, gelatin and other protein
- Used in biscuit manufacturing to lower the protein level of flour
- Remove cloudiness produced during storage of beers.
- Primarily proteases, produced in an extracellular form from bacteria are used for removal of protein stains from clothes
- To remove proteins on contact lens to prevent infections
- Ficin is used to dissolve gelatin off scrap film, allowing recovery of its silver content in the photography industry

- Manufacture of beer, textiles
- In baking, they catalyze breakdown of starch in the flour to sugar. Yeast fermentation of sugar produces the carbon dioxide that raises the dough
- Production of high fructose corn syrup with amylases, glucoamylases, glucois omerases from fungi and plants
- Clarification of fruit juice where turbidity is caused by starch
- Detergents for machine dish washing to remove resistant starch residues
- Degrade starch to lower viscosity, aiding sizing
- Coating paper

- To predigest baby foods

Barley enzymes
- Enzymes are released from barley which degrade starch and proteins to produce simple sugar, amino acids and peptides that are used by yeast for fermentation.during the production of beer
- Industrially produced barley enzymes are used in the brewing process to substitute for the natural enzymes

Acetolactatedecarboxylase (ALDC)
- Increases fermentation efficiency by reducing diacetyl formation

- Used for cheese making

- Used in the breakdown of lactose to glucose and galactosein milk and buttermilk

- Used in making cheese from pastuerized milk
- Used during the production of Roquefort cheese to enhance the ripening of the blue- mold
- Reduce pitch and lignin- degrading enzymes remove lignin to soften paper
- Used to assist in the removal of fatty and oily stains

- Production of fructose

Betaglucanases and arabinoxylanases
- Improve the wort and beer filtration characteristics

Amyloglucosidase and pullulanases
- Low calorie beer and adjustment of fermentability

- Clarify fruit juices
- Used to break down cellulose into sugars that can be fermented (see cellulosic ethanol)
- Degrades starch to lower viscosity, aiding sizing and coating paper
- Used in biological fabric conditioners

- Clarify fruit juices

- Derived from the stomachs of young ruminants, used in manufacture of cheese, to hydrolyze protein
- Microbially produced enzymes are also finding increasing use in the dairy industry

- Used as meat tenderizers to soften meat for cooking

Amyloglucosideases and glucoamylases
- Converts starch into glucose and various syrups

Glucose isomerase
- Converts glucose into fructose in production of high fructose syrups from starchy materials. These syrups have enhanced sweetening properties and lower calorific values than sucrose for the same level of sweetness

- Reduce bleach required for decolorising; cellulases smooth fibers, enhance water drainage, and promote ink removal

- For use of lignin waste
- Degrade starch to lower viscosity, aiding sizing and coating paper

- To generate oxygen from peroxide to convert latex into foam rubber
Molecular biology

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