Introduction:
Enzymes are extra-ordinarily efficient selective biological catalysts. Every living cell has hundreds of different enzymes catalyzing the reaction essential for life. Even the simplest living organisms contain multiple copies of hundreds of different enzymes.
Enzyme-catalyzed reactions are typically 10 to 10 times faster than the corresponding uncatalyzed reactions.
The name of enzymes is derived from a Greek word meaning “in yeast”. It indicates that these catalysts are present inside the cells. In the later 1800s, scientists studies the fermentation of sugars by yeast cells.
Vitalists (who maintained that organic compounds could be made only by living cells) said that intact cells were needed for fermentations. A generation later, In 1926, James B. Sumner crystallized the first enzyme (urease) and proved that it is proteins.
The existence of enzymes has been known for well over a century. Some of the earliest studies were performed in 1835 by the Swedish chemist Jon Jakob Berzelius who termed their chemical action catalytic.
It was not until 1926, however, that the first enzyme was obtained in
pure form, a feat accomplished by James B. Sumner of Cornell University. Sumner was able to isolate and crystallize the enzyme urease from the jack bean. His work was to earn him the1947 Nobel Prize.
John H. Northrop and Wendell M. Stanley of the Rockefeller Institute for Medical Research
shared the 1947 Nobel Prize with Sumner. They discovered a complex procedure for
isolating pepsin. This precipitation technique devised by Northrop and Stanley has been used to crystallize several enzymes.
Some enzymes consist solely of proteins. Other also have a non-proteins part known as a co-factor, essential for the proper functioning of the enzymes. The co-factor is usually act as “bridge” between the enzymes and its substrate. Co-factor provides a source of chemical energy. e.g metal ion act as a co-factor Fe++, Fe+++, Cu++, Co++, Zn++, Mn++, Mg++, Ca++,
Detachable co-factor is known as an activator if it an inorganic ion, non proteins covalently bonded part is known as prosthetic group. Coenzymes are loosely attached to the protein part. Many enzymes are simply dissolved in the cytoplasm. Enzymes are important in photo-synthesis are found in “mitochondria”. They produced by living cells.
Structure:
The active site of enzymes is made up of two definite regions, i.e. the binding site and the catalytic site. The binding site helps the enzymes in the recognition and binding of a proper
substrate to produced and ES complex.
Functions:
Enzymes tremendously increase the efficiency of a biochemical reaction and are specific for each type of reaction.
The major function are given below:
1. they increase the rate of reaction with out them selves being used up.
2. their presence does not effect the nature are properties of end products.
3. small amounts of an enzymes can accelerate chemical reactions.
4. they are sensitive to even a minor change in PH, temperature and substrate concentration.
5. they lower the activation of the reactions.
6. some enzymes are potentially damaging if the are manufactured in their active form.
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