A natural fibrous Protein that is the primary building block for epidermal tissue. Keratin contains all of the common amino acids, but has higher amounts of cystine than other fibrous structural proteins. Sulfur atoms in the cystine amino acid groups are linked by disulfide bonds thus forming polypeptide chains. Soft keratins are found in the external layers of skin, Wool, Hair, feathers, while hard keratins are the major components of tortoiseshells, nails, hoofs, scales, bills, and claws. In the hard keratins, the disulfide bonds of cystine are crosslinked. From the mid-1600's, hornsmiths molded keratin materials into buttons, combs, and buckles. Keratins are relatively stable to changes in relative humidity but are damaged by heat, acids, alkalis, and insects. Storage in ethanol and ethanol/formalin can shortened the expected lifetime of keratin artifacts (von Endt et al 2000).
Synonyms and Related Terms
queratina (Esp.); kératine (Fr.); cheratina (It); Albuminoid
Damaged by alkalis and most bleach solutions. Decomposes in boiling water. Susceptible to moth larvae and other protein-feeding insects.
Physical and Chemical Properties
Insoluble in organic solvents and dilute acids. Slightly hygroscopic.
Resources and Citations
- D.W. von Endt, E.R.Yourd, P.E.Hare, "Spirit Collections: Accelerated Aging Studies Concerning the Stability of Keratin in Ethanol and Formalin" Collection Forum 14(1-2):66-77, 2000.
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