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A protein secreted by spiders and silkworms which rapidly solidifies into strong, insoluble thread that is used to form webs or cocoons.



a simple protein, the principal component of the natural silk and spider-silk fibers secreted by the silk-secreting glands of certain insects and the silk glands of spiders and other arthropods. Fibroin is a viscous, syrupy fluid, that hardens in the air to a tough, insoluble filament. Fibroin threads, coated with the protein sericin, form a silk fiber, as in silkworm cocoons.

Fibroin belongs to a group of structural proteins called scleroproteins. It is resistant to organic solvents, dilute acids and bases, and proteolytic enzymes. The fibroin molecule consists of an elongated polypeptide chaino with repeating structural units, measuring approximately 7 Å. The group of amino acids in fibroin includes a high content of glycine (43 percent), alanine, serine, and tyrosine. The content of the amino acid tyrosine in fibroin is so much higher than in other proteins that fibroin is usually used as the prime source for obtaining tyrosine.

References in periodicals archive ?
Natural silk is a protein polymer consisting of two proteins: fibroin and sericin.
An important source of fibroin is the cocoon of the silkworm (Bombyx mori), which is found in high proportion in Colombia and whose production area is about 400 thousand hectares in the departments of Caldas, Quindio, Risaralda and northern Valle del Cauca (Mesa & Millan, 2008).
The physical structure of the blends were maintained after immersing in water for a period of time, shows that the blends were insoluble in water as compared to silk fibroin, which shows its solubility in water.
Keywords Silk fibroin, Microencapsulation, Coatings, Stabilization, Emulsion, Controlled release
Silk fibroin is a natural polymer produced by various insects.
Cerapedics added that the new product includes silk from larva of the bombyx mori moth that is purified to remove the protein sericin, resulting in biocompatible fibroin fibers that enhance cohesion and mechanical properties.
Among the other materials that are undergoing development in research institutions across the world is 'shrilk' which is incredibly strong and flexible but which because it is made of a combination of the organic polymer chitin (it is found in insect exoskeletons) and fibroin (the insoluble protein in spider silk), is biodegradable.
Mathur, In vivo bone formation in silk fibroin and chitosan.
Available colours are Metallic Matt Fibroin Grey and Brilliant White.
The implants are made of a protein called fibroin, which is extracted from sirk.