Design and function
Collagen is a protein which, as a structural protein, makes up a significant proportion of connective and supporting tissue. It is therefore found in most organs of our body. Collagen belongs to the fiber proteins and has a specific anatomical structure so that it makes a stable protein.
The collagen molecule has a basic structure consisting of three polypeptide chains. These are proteins strung together and consist of up to 1000 individual amino acids, the smallest unit of proteins. The synthesis of a precursor of collagen is first produced in the cells.
The three protein chains are stored together and wound around each other. They form a clockwise rotating basic structure that is approx. 300 nm long and 1.5 nm thick collagen molecule.
This arrangement is known as a triple helix and forms the precursor of collagen. The further production of collagen now takes place outside the cell. Certain enzymes cut peptides from this procollagen at the ends.
Now the individual triplehelices can arrange themselves in parallel and form transverse bridges. This means that the colleague molecules cross-link with each other and thus form a stable and associated scaffold. Under the light microscope, a typical cross striation can be seen, which is caused by the fact that the colleague molecules form fibrils by overlapping their ends.
Several fibrils finally form a collagen fiber. Water molecules then bind to the finished collagen, which means that collagen always has a high water content. The combination of different peptide chains results in different triple helices.
This is why different types of collagen are distinguished, which are usually numbered consecutively, such as collagen type 1, type 2 or type 3. The collagen types occur with varying frequency in the various tissues of our body. In general, collagen is found in skin, bones, fibrous cartilage, tendons, ligaments, teeth, muscle skin and the eye.
The collagen contained in these structures provides the necessary strength and stability. Due to their very elastic properties, bones, cartilage and tendons are tear-resistant, but also flexible. In bones and teeth, it is also involved in mineralization, the formation of bone and enamel, where it is an important component of metabolism.
The organs of our body are usually enclosed by a capsule and fatty tissue. Collagen also forms surface layers and is mostly located in the connective tissue. The organs are thus separated from each other, but remain flexible in their position. Collagen is therefore also involved in the padding and elasticity of our organs and, together with the fatty tissue, takes on a protective function.
