by Rajen M.
Collagen is composed of 3 chains, wound together in a tight triple helix. The illustration above shows a small segment of the entire molecule — each chain is over 1400 amino acids long. A repeated sequence of 3 amino acids forms this sturdy structure. Every third amino acid is glycine, a small amino acid that fits perfectly inside the helix. Many of the remaining positions in the chain are filled by the 2 amino acids — proline and a modified version of proline, hydroxyproline.
The Greeks simply called it glue, and this substance literally holds you together. Collagen, from the Greek work colla (glue), is a protein found in the human body. Protein is the most common substance in the human body after water.
This glue is common structural protein, representing around 30% of our total body protein. It is found in the skin, bones, cartilage, ligaments, tendons, gums, eyes and blood vessels. The skin is made up of up to 60% collagen.
Collagen is a 'structural stabiliser' that provides strength and flexibility. Collagen, in fact, 'holds' you together.
Not surprisingly, collagen is found in other mammals too. It is also found in fish and birds, but never in plants.
Collagen is a fibrous protein. The individual molecules 'cross link'. This gives the connective tissues strength. The hydrogen bonds between the 3 chains of the molecule are responsible for its water holding capacity.
The individual collagen molecule is large — approximately 300KD — and is made up of 3 polypeptide chains tightly wound around each other into a coil like the triple helix structure of DNA. Each individual chain has a typical, repetitive amino acid sequence where amino acids like glycine, proline and hydroxyproline figure prominently.
Types of Collagen
Most people think that collagen is a single protein. It is not. It is actually a family of proteins — a very large family. In fact, a total of 29 types of collagen have been identified to date.
4 types of collagen make about 90% of the collagen in our body and they are aptly named Type I, II, III and IV.
I) Type I is found in the skin, tendon, vasculature and bones
II) Type II is found in cartilage
III) Type III in skin alongside Type I
IV) Type IV is found in cell basement membrane
Our collagen is derived from the food we eat. However, our ability to make collagen is reduced as we age. We also lose collagen when we have burns, injury or lose tissue in surgery. Thus, you should not be surprised that there is strong and active interest in both collagen research and business.
The molecular and packing structures of collagen have eluded scientists for decades and the first evidence that it possesses a regular structure at the molecular level was presented in the mid-1930s. Since that time many prominent scholars, including Nobel laureate Crick and Pauling, Rich, Yonath, Brodsky, Berman and Ramachandran, concentrated on the conformation of the collagen monomer.
Several competing models, although correctly dealing with the conformation of each individual peptide chain, gave way to the triple-helical 'Madras' model which provided an essentially correct model of the molecule's quaternary structure.
Collagen has been widely used in cosmetic surgery, as a healing aid for burn patients for reconstruction of bone and a wide variety of dental, orthopedic and surgical purposes. When used cosmetically, there is a chance of allergic reactions causing prolonged redness though this can be virtually eliminated by a simple and inconspicuous patch testing before cosmetic use.
Most medical collagen is derived from young beef cattle (bovine) from certified BSE (Bovine spongiform encephalopathy) free animals. The manufacturers use donor animals from either 'closed herds' or from countries which have never had a reported case of BSE such as Australia, Brazil and New Zealand.
Collagens are widely employed in the construction of artificial skin substitutes used in the management of severe burns. These collagens may be derived from bovine, equine or porcine, and even human, sources and are sometimes used in combination with silicones, glycosaminoglycans, fibroblasts. growth factors and other substances.
Collagen is also sold commercially as a joint mobility supplement. There is new evidence that collagen hydrolysate, when taken orally help bone re-growth. It was used for this purpose as part of ancient European medicine. Research suggests that collagen hydrolysate can stimulate the synthesis of collagen, which is important for maintaining healthy joints.
There is new effort to develop 'nano' collagen which is minimising the size of the collagen molecule using nanotechnology. This is one of the most active areas in cosmetic research.
More info on COLLAGEN here.
by Rajen M.