Protein, a Primer

Proteins are large molecules made out of one or more long chains of amino acids. They differ mainly in their sequence of amino acids. They usually fold into a specific three-dimensional structure that determines its activity. Proteins are active in all kinds of functions in an organism. They catalyze reactions, replicate DNA, provide structure in cells, transport molecules etc. All the proteins in all the species are commonly made out of 20 standard amino acids, even though more amino acids exist in nature. Plants can synthesize all these amino acids. Animals can not do this but these amino acids are still essential for life so they must get them from the outside, for example through eating meat.

Proteins have different structures. The primary structure is the linear chain of amino acids. The secondary structure is the regular folding of regions of the chain. The most common folds are the α-helix and the β-pleated sheet. The tertiary structure is between regions that are further apart as well as between adjacent residues. The final structure, the quaternary, is a spatial arrangement between the polypeptide subunits. Under the appropriate conditions, proteins fold spontaneously in their native structure. In cells this is aided by accessory proteins. This allows them to fold faster. One class of these accessory proteins is the molecular chaperones. Molecular chaperones include heat shock proteins 70. These help to prevent incorrect folding and aggregation of proteins. Later on we will refer back to heat shock proteins 70, or HSP70, when we talk about heat therapy or sauna use. Remember that animals have to ingest some proteins, that proteins have a three-dimensional structure, and HSP70.

Examples of proteins and their functions

Function Description Example
Antibody These proteins fight foreign substances in the body. Immunoglobulins
Enzyme These proteins regulate the many complex reactions in organisms. Fructokinase
Messenger These proteins help regulate activities and balances in the body. Growth hormone
Structure These proteins provide structure. They are also found in muscle and thus allow bodies to move. Collagen
Transport These proteins ferry atoms and molecules throughout the body. Hemoglobin

Further Reading

Protein. Encyclopedia Britannica.