Elastin is a structural protein found in mammals that confers
elasticity to connective tissues. Examples for the function of
elastin are the elasticity of big blood vessels such as the aorta
or the dimensional stability of pulmonary alveolis. Elastin is made
up of two domain types: A hydrophobic domain consisting of repeats
of oligopeptides rich in glycin, alanine, valine and proline
alternating with a hydrophilic domain that also incorporates lysine
residues.
Soluble elastin is secreted by the cells and covalently linked by
its lysine residues through an enzymatic process. Thereby an
elastin-network is formed that is composed of elastic fibers and is
able to be reversibly stretched for some of its own magnitudes.
The artificial elastin 100xELP has high similarity to human elastin
and consists of oligomeric repeats of the pentapaptide
Val-Pro-Gly-Xaa-Gly (Xaa - any amino acid but proline). Hence it
solely consists of units that resemble the hydrophobic domain of
natural elastin. Therefore it is not able to be linked to a
network. However, 100xELP exhibits a good ability to be solved in
aqueous solution depending on the salt concentration and
temperature. It can undergo an inverse transition, i.e. the protein
is soluble in an aqueous solution below its transition temperature
but insoluble above this critical value.
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