• Stretchy protein within skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava (connect vertebrae → relaxed and stretched conformations).
• Rich in nonhydroxylated proline, glycine, and lysine residues, vs the hydroxylated residues of collagen.
• Tropoelastin with fibrillin scaffolding.
• Cross-linking takes place extracellularly and gives elastin its elastic properties.
• Broken down by elastase, which is normally inhibited by α1-antitrypsin.
  • α1-Antitrypsin deficiency results in unopposed elastase activity, which can cause emphysema.
  • Tobacco inactivates α1-antitrypsin through oxidation of a crucial methionine residue.
• Changes with aging: ↓ dermal collagen and elastin, ↓ synthesis of collagen fibrils; crosslinking remains normal.
• Marfan syndrome
  • Autosomal dominant connective tissue disorder affecting skeleton, heart, and eyes.
  • FBN1 gene mutation on chromosome 15 results in defective fibrillin-1, a glycoprotein that forms extracellular matrix microfibrils, which form a sheath around elastin.
  • Findings: tall with long extremities; pectus carinatum (more specific) or pectus excavatum; hypermobile joints; long, tapering fingers and toes (arachnodactyly); cystic medial necrosis of aorta; aortic incompetence and dissecting aortic aneurysms; stretch marks and lack of skin elasticity; floppy mitral valve. Subluxation of lenses, typically upward and temporally. (Look up at a ceiling fan.)

• β-aminopropionitrile (a chemical found in certain kinds of sweet peas) causes inhibition of lysyl oxidase, an enzyme responsible for cross-linking elastin fibers and collagen fibers.  Ingestion of this compound can cause a change in the elasticity of the aorta that mimics the myxomatous degeneration seen in patients with Marfan syndrome.