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Figure 1. Synthesis and polymerization of elastin. A protein molecule is synthesized in the cell as the precursor tropoelastin and exported to the extracellular environment. A signal peptide of 26 amino acids is cleaved by a signal peptidase from the precursor molecule in step 1. Individual elastin molecules are crosslinked at lysine residues in step 2 by the enzyme lysyl oxidase. Further crosslinking shown in step 3 results in the formation of an insoluble, elastic matrix surrounding the cells and providing strength and elasticity to the tissue.

Bovine Elastin.
A current source of elastin for cosmetic preparations is prepared from bovine tissue. An example is the product Hydroelastin used in Elastin and Collagen Firming Treatment by Rachel Perry. However, the crosslinking of elastin after its synthesis in the skin makes it highly insoluble.

Elastin is released from the tissue matrix by exposing it to hydrolyzing conditions such as alkali and proteolytic enzymes that degrade the polypeptide backbone of the molecule without cleaving the crosslinks formed in the final processing step, leaving a mixture of crosslinked peptides.

This procedure is shown in Figure 2:

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Figure 2. Preparation of soluble elastin from tissue. Exposure to proteolytic enzymes and alkaline conditions is used to break up the solid tissue by cleavage of the polypeptide backbone into much smaller fragments, with some increased water solubility. The final product is a mixture of small, crosslinked peptides.