How Enzymes Work

Enzymes are the biological catalyst that make all life possible. How do enzymes work and why are they are necessary to all life on earth?

Enzymes are chemicals found in living things that act to speed up specific chemical reactions. Enzymes are catalysts for biochemical (living) reactions. If there is any chemical reaction in any living thing there is an enzyme that works to bring it about.

A simple definition of life would be: the transfer of energy through the breakdown of nutrients. In other words, all living things get their energy for life by breaking down the chemicals in other living things. Sounds simple enough but in point of fact, the activity of getting nutrients and energy from food is maybe the most complex group of chemical reactions in the universe. This is because chemical reactions that occur inside living organisms can't happen without a catalyst that would make these reactions happen and control them.

Catalysts are chemicals that while helping a reaction come about, are not themselves changed. Catalysts, in reactions other than biochemical, generally are common inorganic substances which have uses outside of being catalyst for a reaction. For example, platinum is used as a catalyst the reaction that breaks down nitrogen oxides in car exhaust, yet platinum has many other uses. Most biological catalysts, or enzymes, on the other hand are very specific. They exist and are created with only one purpose, to act as a catalyst for one specific reaction biochemical reaction.



Enzymes are proteins which are used as catalysts for a specific reaction. The exact nature of how enzymes work is not known. If is only recently that scientist have had any clue as to the mechanism of enzyme catalyzation. Made up of a complex of amino-acids, enzymes are part of every chemical reaction in living things. Examples of enzyme aided reactions include all digestion, growth and building of cells, any breakdown of substances such as vitamins, and nutrients, all reactions involving transformation of energy. Reactions are also controlled by enzymes. The rate and location or site of a reaction is also controlled by enzyme action. A good example of the involvement of enzyme action is in the building of living material within the cell.

Inside the cell, enzymes create RNA and DNA by facilitating the reaction of ribose with adenosine. They also specify the sites for linking to build RNA along a DNA template. Once the RNA is formed, it is the enzymes that catalyze the construction of proteins from amino acids. It is the catalytic action of particular enzymes that create specific structures within living cells.

Lack of specific enzymes is the cause of many disorders. Disorders such as albinism, diabetes, and cystic fibrosis are traceable to either a lack of a specific enzyme or an imbalance of one.

Some examples of where enzymes are visible in abundance would be in human saliva and in the human digestive tract. Saliva contains an enzyme that breaks down starches into their component sugars. While the stomach combines the enzyme pepsin with acid to speed the digestion of proteins. Enzymes are carried to the intestines to facilitate the digestion of fats.

Another benefit of enzymes in biochemical reactions is that they control the release of energy in living reactions. The breakdown of chemical bonds releases energy. If you were to measure the amount of energy from a candy bar, you would see that it might have 200 calories or more. While the body needs energy to function, the immediate release of chemical energy from the breakdown of food and nutrients would be disastrous. The small candy bar mentioned here would have release enough energy to raise the body temperature of a 200 pound man 3 1/2 degrees Fahrenheit! It is the work of enzymes that allow for the controlled release of the energy in living chemical reactions.

Plants turn the energy of sunlight directly into food by using sunlight energy for chemical bonds in the form of sugar. Enzymes are responsible here, too, they control the absorption of radiant energy. Think about it, have you ever sat under a tree during a hot summer afternoon and wondered what keeps the leaves so cool? The sunshine will be hot enough to melt tar on the streets, but plant leaves remain barely warm to the touch. Where does all the energy go? It is slowly being tied up in the chemical bonds of sugar. The process is photosynthesis and it is the basis of all life on earth, but without enzymes controls this process would be impossible.

Enzymes are at work wherever there is life. Yeast use enzymes to leaven bread and ferment sugar into alcohol. Bacteria use enzymes to break down cellulose fiber in the stomachs of cows and the stomachs of termites. Plants, animals, bacteria, or fungi, if they are alive, use enzymes to control all living chemical reactions. Reproduction, growth, metabolism, synthesis, are all enzyme regulated reactions in living things. Enzymes are the chemicals that make life work.

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