A Search for a Simple Keratin?The Precursor Keratin Proteins From Cow's Lip Epidermis

Abstract

In searching for a material which might contain a homogeneous keratin protein as a major constituent, an examination was made of a soluble keratin precursor from cow's lip epidermis. Formic acid was used as extractant. Assessment of homogeneity was based on behaviour on DEAE-cellulose and on a consideration of the radioactively labelled peptides in a size-charge peptide map of [14C]S-carboxymethylcysteine. containing peptides from an enzyme digest. It is concluded that there is no major homogeneous keratin precursor in cow's lip epidermis and that a family of closely related proteins is present. The situation resembles that found in another a·keratin, wool. There is evidence for the existence of a fraction, amounting to 6-8% of the total protein, of higher sulphur content than the remainder of the protein both in the soluble precursor protein and in the stratum corneum.

Two polypeptide chain constituents of the major protein of the cornified layer of newborn rat epidermis

“…nous proteins has employed S-carboxymethylation with iodoacetic acid (O'Donnell, 1971;Baden and Goldsmith, 1972;Shimizu et al, 1974). Shimizu et al (1974) report the presence of two fibrous protein components of molecular weight 68,000 and 61,000 in cornified cells of newborn rat epidermis.…”