Evidence of homology in a high-sulphur protein fraction (SCMK-B2) of wool and hair α-keratins

Abstract

Fractions corresponding to the S-carboxymethylated high-sulphur protein component SCMK-B2 isolated by Gillespie (1963) from Merino wool were prepared from five different wool samples and also from bovine hair. The six fractions showed great similarities in amino acid composition, and also gave very similar peptide ;maps' after tryptic and chymotryptic digestion. Some of the peptides were isolated from the different samples, and evidence is given that suggests that a sequence of at least 21 amino acids is common to all the fraction SCMK-B2 preparations. Further, all the fractions derived from the wool samples have the same acetylated heptapeptide for the N-terminal sequence, but one extra residue may be present in this N-terminal sequence in the protein from bovine hair. The general significance of these findings is discussed.

The Possibility of Common Amino Acid Sequences in High-Sulphur Protein Fractions from Wool

“…Fractions 13-17 show obvious similarities to patterns previously published for the high-sulphur protein fraction SCMKB2 (Gillespie, Haylett, and Lindley 1968) and on this basis some of the peptides can be identified, since it has been found (Gillespie and Darskus, unpublished data) that SCMKB2 is eluted as a broad peak in this region. Tryptic digests run at pH 3•5 show evidence of a very fast anodic component in fractions 3-7.…”

Selective biodegradation of keratin matrix in feather rachis reveals classic bioengineering

“…We anticipated the possibility of selective biodegradation occurring on the basis of the two general classes of proteins present in keratin, a high-sulphur fraction of the amorphous matrix (derived from the sulphur -sulphur cross-links that keep the fibres intact) and a low sulphur fraction of the microfibrillar component. Although these fractions were determined on a keratins (Alexander & Earland 1950;Gillespie et al 1968;Lindley & Cranston 1974), we believed, as implied by some workers (Wainwright et al 1976), that the fractions might be similar in b keratins. We mention in parentheses subsequent research (Eckhart et al 2008) that shows that cysteine-rich a keratins are not restricted to mammals and that the evolution of mammalian hair may have involved the cooption of pre-existing structural proteins (lizards and birds) and, interestingly, that in the keratins in lizard claws there were sulphur -sulphur bonds unrelated to mammalian counterparts.…”

The Keratin Proteins of Wool, Horn and Hoof from Sheep

“…A high-sulphur protein fraction, SCMK-B2, was prepared from wool, horn, and hoof using the procedures of Gillespie (l963a) and Gillespie et al (1968). The fraction from wool contains three sequenced components-SCMK-B2A, B2B and B2C (Elleman 1972;Lindley and Elleman 1972).…”