Structural protein are essential for providing structure and rigidity to fluid biological cells and components. Structural proteins are fibrous proteins which provide support for the cells. Structural proteins are usually very large and are made up with up to thousands of amino acids. Insects and spiders use silk fibers to for various tasks such as making their cocoons and webs . Another example of a structural protein can be seeing in Keratin which is the protein of hair, feathers and horns among other things . Actin and collagen are specific examples that fall under this category of proteins. Collagen, recognized as one of the most abundant proteins in mammals, is the main component in connective tissue. Collagen can be found in the tendons, ligament and skin. Collagen can also be found abundant in cornea, cartilage, bone, and blood vessels. Collagen composes about 25-35% of the entire protein content in the human body, which illustrates the importance of structural proteins such as this in the body.
Not only proteins serve an important role as the structural components, it also participates in all of the biological processes. For example, transport, storage, catalytic reactions, immunity, nervous system, growth, and etc. There are four general properties that allow proteins to function in such wide varieties:
- Protein is formed with monomers called “amino acids” and it is connected from one end to the other, becoming a linear polymer. The unique sequence of the amino acids causes the chain to fold into three dimensional shapes called “protein,” which the function is also determined by the shape. Because of the endless possible sequences of the amino acids, the folded protein world is also capable of intense diversity and varieties.
- Protein carries many kinds of functional groups such as, thiols, alcohols, carboxylic acid, and etc. Because these functional groups are reactive, it gives the protein wide range of reactive properties.
- Protein’s ability to interact with other macromolecules also increases the range of functions. Unlike other macromolecules, the ability to interact allows the proteins to develop into complex assembly with other molecules.
- The combination of rigidity and the flexibility of the protein is another reason for its usefulness in biological structures. Flexible proteins may work as a spring, hinge, and a lever while ridge proteins can play a role in cytoskeleton structures.
- Berg, Jeremy Mark., John L. Tymoczko, and Lubert Stryer. Biochemistry. New York: W.H. Freeman, 2007. Print.
- Biology, Eight Edition,Pearson, Benjamin Cummings, 2008.