Elastin is the main component of elastic fibers. Elastic fibers are mainly present in the ligaments and vascular walls. Elastic fibers coexist with collagen fibers, giving the tissue elasticity and tensile strength. Elastin is the main component of elastic fibers in raw skin tissue. Elastin's peptide chain contains more than 713 amino acid residues. Unlike collagen and keratin, there is no continuous repeating periodic structure in the amino acid sequence of elastin throughout the peptide chain, but there are alternating hydrophobic and hydrophilic skin segments. Catenin and open-chain catenin formed by oxidizing lysyl are cross-linking structures unique to elastin. These cross-linked structures combine more than two team dimensions. Elastic strong white secondary structure may be a combination of random and indefinite, elasticity is the most important physicochemical property of elastin.
Figure 1. Stretched elastin isolated from bovine aorta.
Physical and chemical properties
Pure elastin is light yellow and blue (under ultraviolet light). Resistant to acid and alkali. Below 100°C, it is insoluble in various hydrogen bond cleavage solvents and swell. Insoluble in phenolic solvents. It is insoluble in any solvents other than the peptide cleaving agent. Elastin is a polymeric substance that has rubber ductility and low elastic modulus in the presence of water.
Figure 2. Clumping of short elastic fibers in the dermis.
Like collagen, elastin is also rich in glycine and proline, but unlike collagen, elastin is not highly hydroxylated and there is no hydroxylysine. Elastin molecules cross-link with each other through covalent bonds formed by lysine residues, and the cross-linking network they form can generate elasticity through configuration changes. Although collagen can give extracellular matrix strength and toughness, it needs to be elastic for some tissues. This is especially true for tissues such as the lungs and heart. This elasticity is mainly dependent on the elastic fibers in the extracellular matrix. The elastic fiber is like a rubber band. Its length can be extended to several times its normal length, and it can return to its original length when it shrinks. The elasticity of the tissue is controlled by changing the amount of collagen dispersed in the elastic fibers. The elastin fiber network gives the tissue elasticity, and the stretchability of the elastic fiber is at least 5 times larger than the rubber strip with the same cross-sectional area. Elastin consists of two types of short peptides arranged alternately. One is the hydrophobic short peptide that gives the molecule elasticity; the other short peptide is the a-helix that is rich in alanine and lysine residues and is responsible for the formation of crosslinks between adjacent molecules. The amino acid composition of elastin is similar to collagen, but also rich in glycine and proline, but it rarely contains hydroxyproline, does not contain hydroxylysine, and has no collagen-specific Gly-XY repeats, so it does not form a regular triple helix. structure. Cross-linking between elastin molecules is more complicated than collagen. The lysine residues participate in the cross-linking to form an elastic network structure.
Figure 3. Elastin replacing collagen fibers of the papillary dermis and reticular dermis.
Skin care effect
Many people believe that the key to maintaining skin youth is how to supplement collagen, but elastin is more important. Elastin plays the role of a rubber band in the skin, giving the skin the ability to stretch and fold. Its function is like a spring in a mattress, which is responsible for maintaining and supporting the elasticity of the skin. Therefore, elastin plays an important role in maintaining skin elasticity.
Elastin determines the elasticity and softness of the skin. It has the effects of preventing physical aging and promoting regeneration by physical and chemical factors such as light.
Many people believe that the key to maintaining skin youth is how to supplement collagen, while ignoring another important substance in fibroblasts-elastin. It plays the role of a rubber band in the skin. If skin care products contain both elastin and collagen, it will have a very good effect on keeping the skin young, delicate and elastic.