Collagen are class of macromolecules (a molecule formed by hundred of atoms) which are a main compound of many tissues and bones in animals.
Formula and structure: Collagen can be classified in some types, but the most known and studied is the type II collagen. The type II collagen molecular mass is 1461.64 g mol-1 and the molecular formula is C65H102N18O21. The collagen is always found as a group of three molecules, that are twisted together to form a collagen aggregate of 290 nm long and 1.5 nm diameter approximately. Its chemical structure can be written as below, in the common representations used for organic molecules.
Occurrence: Collagen is a much extended natural molecule. It is found in many tissues such as skin, tendons, ligaments, cartilage and it is also found in bones, corneas and blood vessels. Particularly in muscle tissue it is very abundant.
Preparation: The collagen is biosynthesized through diverse biological processes. The first ste is the formation of a pre-peptide structure that suffers many modification to produce a pro-collagen structure. The pro-collagen also suffer post-translational modifications to produce a tropocollagen molecule (or single structure of collagen) and three of these structures form the collagen fibril.
Physical properties: Collagen is a fibrous white to colorless gel. Collagen melting and boiling points are 30-50 ºC and 160-190ºC, respectively and depending on the source where it is extracted. It is poorly soluble in water, but is soluble in acetic acid.
Chemical properties: Collagen is a type of protein very studied due to its structure is full of α – helix structures. Thus, it is the standard for the study of proteins with a high content of alpha helix structures. The type of interactions that keep together the structure is the covalent bonds between the three tropocollagen molecules.
Uses: Collagen is largely used in cosmetic and pharmaceutical industries, where it is an important raw material to manufacture cosmetic products or equipments for surgery or even implants. It also used in food industry to produce gelatin and its derivatives.
Health effects / safety hazards: Collagen is not dangerous to handle. It is not toxic or flammable.