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An insoluble, white, fibrous protein. Fibroin is the primary structural component of silk, secreted along with sericin by the insect. Unlike wool, silk is composed mainly of non-sulfur containing amino acids. The primary amino acids, glycine, alanine and serine, are contained in dense, highly crystalline regions of the fiber. The amorphous regions are composed of tryosine, tryptophane, histidine and phenylalanine.

Synonyms and Related Terms

fibroína (Esp.); fibroïne (hoofdbestanddeel van ruwe zijde) (Ned);

Physical and Chemical Properties

Soluble in concentrated acids and alkalis. Insoluble in water, ethanol and ether.

Resources and Citations

  • E.Hansen, H.Sobel, "Effect of the Environment on the Degradation of Silk: A Review" in The Textile Specialty Group Postprints, AIC, Buffalo, p.114-130, 1992.
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998