Tropoelastin is a water-soluble molecule with a molecular weight of approximately 72,000 daltons. Multiple tropoelastin molecules covalently bind together with crosslinks to form the protein elastin that is very prevalent in the body. There is only one gene for this molecule and so only one protein. However, occasional splicing provides tissue specificity.
There are 36 small domains in Tropoelastin and each weighs about 2 kilodaltons. Within the exons, there is alternating hydrophobic and Lysine-rich domains, this is important in forming Elastin. Tropoelastin does not undergo cleavage and forming the microfibril is achieved by a self-association process termed coacervation.
Tropoelastin aggregates at physiological temperature due to interactions between hydrophobic domains. This process is reversible and thermodynamically controlled. The coacervate is stabilized by cross-linking via lysyl oxidase. The coacervate then becomes insoluble and the process is irreversible. It then condenses to form a cross-linked structure of 4 residues, either Desmosine or Isodesmosine.
Tropoelastin is unusual in that it exists in multiple forms, called polymorphs. Tropoelastin is not normally available in its native state, since it becomes crosslinked immediately after its synthesis by the cell and during its export into the extracellular matrix. Tropoelastin confers strength and elasticity to the skin and other organs in the body. A synthetic form of human tropoelastin is made by DermaPlus Products from genetically modified organisms for use in wound healing and topical skin care.
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