Formation of the Triple Helix
All collagens contain three polypeptide chains that become coiled around each other to form what is known as a triple helix. These triple helices in turn also wrap around each other to form coils. Polypeptide chains have high amino acid content and generally contain approximately 1,000 amino acids.
Creation of Collagen Fibrils
A triple helix is significantly longer and greater in density than the common alpha helix found in most proteins. Three triple helices bind and coil around each other to form a molecule known as a tropocollagen. This molecule forms the most basic outline of the collagen itself. Side chains made of amino acids called glycine coil around a centralized axis, forming what is known as a superhelix. Glycine is structurely finer and smaller than most other amino acids and better composes these side chains. These main tropocollagen structures merge together in a stair-stepped fashion to create collagen fibrils.
Collagen Formation and Structure
Collagen fibrils are very strong and can support weights comparable to that of steel wire. This strength comes from the stabilization of many covalent bonds known as covalent cross links. These not only exist within the fibrils, but also between the tropocollagen molecules themselves. Crosslinks are bonds incorporating the use of hydroxylysine and lysine side chains. How extensive this cross-linking is depends on how active the collagen production through these processes in relation to the age of the animal producing it. More mature animals have more cross-links and in turn have a rougher and less smooth collagen makeup. The younger the skin of an animal, the softer and smoother it is.
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