An enzyme is a catalyst for a biological chemical reaction. It is classified as a protein.
An enzyme is any of numerous complex proteins that are produced by cells and living organisms and function as biochemical catalysts, initiating and expediting various chemical processes. Enzymes are essential to almost all biological processes. For instance, enzymes in the saliva in one’s mouth help to start the process of breaking down food. Additionally, they are a key ingredient in the sending and processing of biological information via signal transduction (the way cells respond to environmental stimulus). They also make possible some of the most extraordinarily complex life protecting cascades such as blood clotting.
Without enzymes, cells would not be able to create their essential chemical reactions quickly enough to sustain life. The mutation or disfunction of any gene that creates an essential enzyme will lead to a severe disease, and possibly even death. For instance, phenylketonuria is caused by the dysfunction of the enzyme phenylalanine hydroxylase, and ultimately leads to mental retardation.
Enzymes can speed up chemical reactions by a factor of millions. And as it only has to be present and is not changed, an enzyme can be reused hundreds of times. Enzymes are specific to specific chemical reactions. It's thought that this is due to the molecular shape of an enzyme, that it only fits in any given chemical in a specific way.
The action of an enzyme can be diminished or eliminated with an inhibitor. Many drugs, notably anti-inflammatory drugs, are enzymatic inhibitors. Certain inhibitors, like heavy metals (mercury and lead), bind permanently and irreversibly to an enzyme, preventing it from catalyzing permanently. This is probably the genesis of heavy metal poisoning. Nerve gas acts on enzymes similarly, destroying the catalyst that works with neurotransmitter acetylcholine and causing protracted muscle contractions, paralysis, and death.
Enzymes are used outside the body as well; laundry detergents add enzymes for enhanced cleaning of organic stains. You'll also find them in baby foods and steak tenderizer, beer brewing, cheese manufacture, and the manufacture of glucose and fructose.
There are over 5,000 enzymes we know of today. Many work effectively by themselves, while others need to be activated or work only in the presence of an enzyme cofactor.
An enzyme reaction involves 1) a substrate (the substance that is effected by the enzyme), 2) the enzyme, whose functional role is specified by its active site and 3) the product that results from the catalysed reaction. Enzymes are usually quantified by measuring the production of product. It is important to point out that enzymes are not changed throughout the catalysing process, and thus be recycled and reused.
The active site of the enzyme has a particular shape which determines the type of substrate to which it can bind. The active site specifies the type of reaction that will occur and determines the specific role that an enzyme plays in catalytic processes. Enzyme activity can be slowed down or completed stopped by changing the shape of or blocking the active site.
Enzymes play a key role in metabolism. In addition to the enzymes in our saliva, metabolic enzymes are also released from the pancreas in order to break down carbohydrates, proteins and fats. These will include protease to break down proteins, amylase to break down sugars and lipase to break down fats.
Enzymes are usually quantified by their activity and to a lesser degree, their concentration in terms of protein. To measure the rate of activity you have to measure the rate of the production of the product to determine the appearance of small quantities of a product. A common way of expressing enzyme activity is in terms of units which are often defined as “that amount of enzyme to produce 1 mole of product per minute”. Many unit definitions exist and there is no international standard. The measurement technique and unit definition often depends on the enzyme being studied. Protein concentration is measured using various protein assay techniques.
Web Resources On Enzyme
Reactions and Enzymes
Book Resources On Enzyme
The organic Chemistry of Enzyme-catalyzed Reactions by Richard B. Silverman
Enzymes and Enzyme therapy: How to Jump Start Your Way to Lifetime Good Health by Anthony J. Cichoke
Enzymes: A Practical Introduction to Structure, Mechanism, and Data Analysis by Robert A. Copeland