Protein

Proteins are large, complex structures that play an important role in a living system. Proteins form the fundamental basis of structure and function of life. In the form of skin, hair, callus, cartilage, muscles, tendons and ligaments, proteins hold together, protect and provide structure to the body of a multi-cellular organism. In the form of enzymes, hormones, antibodies and globulins, they catalyse, regulate and protect the body chemistry. In the form of haemoglobin, myoglobin and various lipoproteins, they effect the transport of oxygen and other substances within an organism.
Proteins constitute about 80 percent of the dry weight of muscle, 70 percent of that of skin, and 90 percent of that of blood. The interior substance of plant cells is also composed partly of proteins. The importance of proteins is related more to their function than to their amount in an organism or tissue. All known enzymes, for example, are proteins and may occur in very minute amounts; nevertheless, these substances catalyze all metabolic reactions, enabling organisms to build up the chemical substances--other proteins, nucleic acids, carbohydrates, and lipids--that are necessary for life.(oregon)
Proteins are nitrogenous macromolecules composed of many amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function.
==Etymology==
The term protein is derived from a Greek word proteios, meaning first place. Berzelius, a swedish chemist, suggested the name proteins to the group of organic compounds that are utmost important to life.
==Function==
(nih.gov)
Proteins tend to stick, or bind, to other molecules. In some cases, the binding is strong and in others it is weak or of short duration. But their is specificity involed in the binding of a protein molecule i.e. it can usually only bind with one or few molecules out of several thousands of different types it encounters. The substance that is bound by a protein is referred as a ligand for that protein.
The ability of a protein to bind selectively and with high affinity to a ligand depends on the formation of a set of weak, noncovalent bonds and favourable hydrophobic interactions. Because each individual bond is weak, an effective binding requires several weak bonds to be formed simultaneously. It is possible when surface contours of the ligand molecule fit very closely to the protein, similar to a key matching to its lock.
There are several categories of protein functionalities:-
*Antibody: Antibodies bind to specific foreign particles, such as viruses and bacteria, to help protect the body.
*Enzyme: Enzymes carry out reactions that take place in cells. They act as catalysts in body functions. They also assis with the formation of new molecules by reading the genetic information stored in DNA.
*Messenger: Messenger proteins, such as some type of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs.
*Structural Component: These kind of proteins provide structure and support for cells. On a larger scale, they also allow the body to move.
*Transport/storage: These proteins bind and carry atoms and small molecules within cells and throughout the body.
Category:Biology