Elastin peptide Cas No: 9007-58-3 is a protein naturally produced within the body. Elastin is formed of peptides, fibroblasts, and amino acids, which are structured in a particular shape that determines its function. Elastic fibers are bundles of elastin found within the dermis (middle layer) of the skin, as well as in blood vessels, the lungs, ligaments, and more. Elastin’s main purpose is to provide flexibility to cells.