Over 75% Of Young Skin Is Composed Of CollagenOver time the collagen breaks down and this decreases the elasticity of the skinOne of the main structural elements of the skin is represented by collagen. The collagen family contains approximately 28 different proteins, which account for 30% of the total protein mass in the human body. The common structural feature of collagens is the presence of three polypeptide chains named α-chains, which form a triple helix [1]. 
Multiple triple helices form a collagen fibril. Generally collagen fibrils are made of different collagen types: collagen I and III in the skin; collagen II and III in cartilage [1]. The diversity of the collagen family (collagen I, II, III) is mainly determined by the existence of several α-chains with different numbers of amino acids. The unique physical properties of collagen fibres confer structural integrity to the skin forming a dense network throughout the dermis.
The main function of this network is to provide structural support to the epidermis. In addition, collagen and elastin together form the extracellular matrix, which gives the skin its structure, elasticity and firmness [2]. Collagen is recognised by the medical and scientific community for providing a structural support for most tissues in the body, and is particularly abundant in the connective tissue. Normal collagen formation is also required for the structure of many other tissues, including bones, cartilage, gums, tendons and blood vessels. The collagen in the skin is mainly produced by fibroblasts. These are connective tissue cells in the dermis which are responsible for not only producing and organising the collagen matrix, but also for supplying the skin with elastin and hyaluronic acid. Fibroblasts are sensitive to physical and chemical stimuli, which can induce both fibroblasts activation and proliferation. The activation of fibroblasts results in an increase in the production of collagen. 
The mechanism of collagen formation is well known and is herein briefly described. The genetic information encoded in the DNA is “read” (transcription process) and then “translated” (translation process) to produce single polypeptide chains (α-chains). Each α-chain has a terminal peptide sequence, also known as trimerization domain, which drives the assembly of the polypeptide chains to form a molecule of pro-collagen. Finally the terminal peptides are cleaved during the maturation process to form collagen. 
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