440 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS isolated from reduced wool and partially characterized by Zahn and Biela (95). For the first time the complete amino acid sequence of three homogen- eous proteins, isolated from SCMKB fraction of Merino wool, has been established by Haylett, Swart and co-workers (96). The S-carboxymethylated proteins have a molecular weight of 11 409 4- 150. They consist of single chains containing 97 or 98 residues. Their N-terminal sequence is Ac-Ala- Cys(CH•.CO•.H) and they have S-carboxymethylcysteine as C-terminus. The molecules can be divided arbitrarily at position 49 into high- and low- sulphur proteins but the amino acids that prevent helix formation, such as proline, serine, and threonine, are fairly evenly distributed throughout the molecules. These high-sulphur proteins therefore appear to have no helical content and are ideally suited for the function of matrix protein in wool. The work of Corfield, Fletcher and Robson (97) on a protein fraction, isolated in 365/o yield from oxidized wool, has led these authors to suggest that wool consists of only one main protein composed of relatively short helical regions interspersed with sequences rich in cystinc, proline, serine, and threonine residues. It is suggested that this fraction is derived from a protein that constitutes the major part of the cortex. Further evidence in this field may therefore provide direct chemical evidence regarding the validity of the concept of the two-phase two-protein theory. ACKNOWLEDGEMENTS The author is grateful to Professor R. S. Asquith and Dr. J. A. Swift for helpful suggestions and comments. Figs. 1-5 were kindly supplied by Dr. Swift. (Received: $rd January 1972) REFERENCES (1) Astbury, W. T. and Woods, H. J. X-ray studies of the structure of hair, wool and related fibres. II. The molecular structure and elastic properties of hair keratin. Phil. Trans. Roy. Soc. London. A232 333 (1933). (2) Pauling, L., Corey, R. B. and Branson, H. R. The structure of proteins: two hydrogen- bonded helical configurations of the polypeptide chain. Proc. Nat. Acad. Sci. U.S. 37 205 (1951). (3) Lundgren, H. P. and Ward, W. H. in Borasky, R. Ultrastructure of Protein Fibres 39 (1963) (Academic Press, New York). (4) Mercer, E. H. and Matoltsy, A. G. Keratin, in Montagna, W. and Dobson, R. L. Advances in Biology of Skin, Vol. 9, Hair Growth (1969) (Pergamon, Oxford). (5) Ward, W. H. in Alexander, P. and Lundgren, H. P. Analytical Methods of Protein Chemistry, Vol. 4, 185 (1966) (Pergamon, Oxford). (6) Crewther, W. G., Fraser, R. D. B., Lennox, F. G. and Lindley, H. The chemistry of keratins. Advan. Protein Chem. 20 191 (1965).

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