Enzymes

Enzymes are proteins that act as biological catalysts. They decrease the amount of energy needed (activation energy) to start a metabolic reaction. Without enzymes, organisms are not being able to harvest energy and nutrients from food. One common example is the Lactose intolerance. Lactose intolerance is the inability to produce lactase, the enzyme that breaks down milk sugar (lactose).

Functions of Enzymes

Enzymatic reactions can build up or break down specific molecules. The specific molecule an enzyme works on is the substrate. In the function of the Enzyme, Shape is very critical. We note that enzymes are complex proteins with specific three dimensional spatial shapes. The “active site” of an enzyme is the area where substrate binds and the reaction takes place. How an enzyme reacts with its substrate is similar to how a lock and key work. There are minor bonds that form between the enzyme and substrate until locking and unlocking is done.

Anything affecting the shape of the key would make the key unable to lock and unlock.

Naming of Enzymes

The naming of the enzymes is peculiar. Individual enzymes are named by adding the suffix “ase” to the name of the substrate with which the enzyme reacts. For example enzyme amylase controls the breakdown of amylose (starch), hydrolases control hydrolytic reactions; proteinases control protein breakdown; synthetases control synthesis reactions. However, some enzymes retain their name from older system when this ‘ase’ nomenclature was not adopted. Examples are trypsin and pepsin, both digestive enzymes that breakdown protein.

Applications of Enzymes

Enzymes are used in the chemical industry and other industrial applications when extremely specific catalysts are require. For example:

• Amylases from fungi and plants are used in Food Processing Industry. For Instance, production of sugars from starch, such as in making high-fructose corn syrup.
• Proteases are used by the biscuit manufacturers to lower the protein level of flour.
• Trypsin enzyme is used in the making of Baby Foods
• Several enzymes are used in making wines and whiskeys. Enzymes from barley are released during the mashing stage of beer production.
• Cellulases, pectinases are used in packing juices; they help to clear the cellulose from juice.
• Rennin, derived from the stomachs of young ruminant animals (like calves and lambs) are used in the dairy industry to produce Cheese.
• Papain obtained from Papaya is used as a softener in meat cooking.
• Amylases, Xylanases, Cellulases and ligninases are used in Paper Industry.

• A class of drugs called protease inhibitors are powerful HIV-fighting medications Protease inhibitors prevent T-cells that have been infected with HIV from making new copies of the virus.

Enzymes and pH

Since changes in temperature and pH can cause the structure of a protein to change, every enzyme has criteria that must be met in order for it to perform its function. For example, the amylase that is active in the mouth cannot function in the acidic environment of the stomach; pepsin, which breaks down proteins in the stomach, cannot function in the mouth.

Spinach TNT and Enzymes

TNT is a dangerous explosive. Spinach contains a powerful enzyme called nitro-reductase that is able to neutralize TNT by converting it to other compounds that are less dangerous. Through additional reactions, these less-harmful compounds can be converted to carbon dioxide gas.

Enzyme cofactors

Few enzymes need other associated molecules to do their job properly. These molecules are called enzyme cofactors. They can be organic ions like mineral salts, or organic molecules, or Vitamins. Inactive enzymes which are not bound to their cofactors are called apoenzymes. Active enzymes bound to their cofactors are called holoenzymes.

Use of Enzyme Inhibitors in Health Science

Substances that “simulate” substrates can bind to the activation center of enzymes, thus blocking the true substrates from binding to these enzymes and paralyzing the enzymatic reaction. These “fake substrates” are called enzyme inhibitors. Many Pharma drugs such as some antibiotics are enzyme inhibitors that block enzyme activity. We note here that Penicillin {first antibiotic discovered} inhibits the enzymes necessary for the synthesis of peptidoglycans, a component of the bacterial cell wall. Using this would block growth of the bacteria and this is what won Nobel Prize for Alexander Fleming for discovery of penicillin. Similarly, some antiretroviral drugs called “protease inhibitors” are used against HIV infection. Protease is an enzyme necessary for the construction of the  human immunodeficiency virus (HIV) after the synthesis of its proteins within the host cell. The protease inhibitor binds to the activation center of the enzyme blocking the formation of the enzyme-substrate complex and enzyme activity, thus stopping viral replication.