ElastinTropoelastin: A salt-soluble precursor of elastin. Lysyl oxidase is instrumental in converting it to elastin in connective tissue.Desmosine: A rare amino acid found in elastin, formed by condensation of four molecules of lysine into a pyridinium ring.Elastic Tissue: Connective tissue comprised chiefly of elastic fibers. Elastic fibers have two components: ELASTIN and MICROFIBRILS.Isodesmosine: 2-(4-Amino-4-carboxybutyl)-1-(5-amino-5-carboxypentyl)-3,5-bis(3-amino-3-carboxypropyl)pyridinium. A rare amino acid found in elastin, formed by condensation of four molecules of lysine into a pyridinium ring.Pancreatic Elastase: A protease of broad specificity, obtained from dried pancreas. Molecular weight is approximately 25,000. The enzyme breaks down elastin, the specific protein of elastic fibers, and digests other proteins such as fibrin, hemoglobin, and albumin. EC 6-Oxidase: An enzyme oxidizing peptidyl-lysyl-peptide in the presence of water & molecular oxygen to yield peptidyl-allysyl-peptide plus ammonia & hydrogen peroxide. EC Shiny, flexible bands of fibrous tissue connecting together articular extremities of bones. They are pliant, tough, and inextensile.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Aortic Stenosis, Supravalvular: A pathological constriction occurring in the region above the AORTIC VALVE. It is characterized by restricted outflow from the LEFT VENTRICLE into the AORTA.Cutis Laxa: A group of connective tissue diseases in which skin hangs in loose pendulous folds. It is believed to be associated with decreased elastic tissue formation as well as an abnormality in elastin formation. Cutis laxa is usually a genetic disease, but acquired cases have been reported. (From Dorland, 27th ed)Aorta: The main trunk of the systemic arteries.Matrix Metalloproteinase 12: A secreted matrix metalloproteinase which is highly expressed by MACROPHAGES where it may play a role in INFLAMMATION and WOUND HEALING.Williams Syndrome: A disorder caused by hemizygous microdeletion of about 28 genes on chromosome 7q11.23, including the ELASTIN gene. Clinical manifestations include SUPRAVALVULAR AORTIC STENOSIS; MENTAL RETARDATION; elfin facies; impaired visuospatial constructive abilities; and transient HYPERCALCEMIA in infancy. The condition affects both sexes, with onset at birth or in early infancy.Elasticity: Resistance and recovery from distortion of shape.Connective Tissue: Tissue that supports and binds other tissues. It consists of CONNECTIVE TISSUE CELLS embedded in a large amount of EXTRACELLULAR MATRIX.Extracellular Matrix: A meshwork-like substance found within the extracellular space and in association with the basement membrane of the cell surface. It promotes cellular proliferation and provides a supporting structure to which cells or cell lysates in culture dishes adhere.Aminopropionitrile: Reagent used as an intermediate in the manufacture of beta-alanine and pantothenic acid.Microfibrils: Components of the extracellular matrix consisting primarily of fibrillin. They are essential for the integrity of elastic fibers.