What Is Elastin?

Elastin is an insoluble extracellular matrix protein found in arteries, lungs, skin and ligaments. It is the core component of the elastic fibers that give these tissues their elasticity.

It is first made in a soluble form (tropoelastin) and, after leaving the cell, binds with other proteins to form insoluble elastic fibers.

Elastin is abundant in tissues that stretch and recoil repeatedly. It turns over very slowly in the body; its half-life is estimated at about 70 years.

Most of the dermis is made of extracellular matrix such as collagen fibers and elastic fibers. Collagen is a strong, tough protein, while elastin is the source of tissue elasticity.

At the outflow of the fish heart is the “bulbus arteriosus.” In other vertebrates this part is cardiac muscle, but in teleost fish it is elastin-rich smooth muscle. Because the gills lie just beyond the heart, the bulbus cushions the pressure of each heartbeat. Elastic fibers are said to occupy about 70% of the chamber, and teleosts carry an extra elastin gene for the bulbus that humans and mice lack.

Bonito elastin is elastin taken from this bulbus arteriosus.

Fish vs. land-animal elastin

A study comparing salmon bulbus and bovine aortic elastin found that fish elastin has more glycine and tyrosine and fewer hydrophobic amino acids such as alanine and valine, with fewer cross-links, making it softer.

Residues per 1,000 amino acids, measured the same way in one study (selected amino acids).

Cross-linking amino acids (desmosine)

Desmosine and isodesmosine, found only in elastin, are used as quality markers. The industry standard requires at least 0.1 g per 100 g of hydrolyzed elastin for fish-derived and at least 0.8 g for mammal-derived elastin.

After eating

After eating hydrolyzed bonito elastin, the most abundant food-derived peptide in the blood was prolyl-glycine (Pro-Gly), peaking at 30 minutes and falling to about 20% after four hours. Elastin peptides from the bonito bulbus are also being studied at other universities.

Tissue stretch and recoil are carried by elastic fibers, and their breakdown and deterioration are thought to be related to age-related changes in the body.