Collagen Notes

Date:
1957-1961
Reference:
PP/CRI/H/2/20/3
Catalogue details

Licence: In copyright

Credit: Collagen Notes. Source: Wellcome Collection.

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    Voi-. 43, 1957 CHEMISTRY: DOTY AND LU N DB ERG 213 ' H. S. Hear, Advance* in Protein Chemistry, 7, 69, 1952. ; H. M. Badger and A. 1). K. Piillin, J. Chem. Phys., 22, 1142, 1954. I J. A nil tros*' and A. Elliott, Proc. Roy. Soc. London, A, 206, 206, 1951. * < I H. li M. Sutherland, K N. Tanner, and D. L. Wood, J. Chem. Phys., 22, 1621, 1954. W. li Seeds, in The Sature and Structure of Collagen, ed. J. T. Handall (Butterworth's Scientific Putilications) (London: Butterworth & Co., Ltd.; New York: Academic Press, Inc., 1953), p. 250. (J H. Tristram, in The Proteina, ed. H. Neurath and K. Bailey (Now York: Academic Press, Inc.. 1953 . V..I.1, Part A. '■ Analyses show that the amount of amide nitrogen is practically equivalent to the amount of «spartic acid obtained, suggesting that in the native material the aspartic residues are present in amide form, or as an amide condensation product, with the glutamic residues in an acidic form or as an acid condensât ion product. ' T I ). Kroner. W Tal.roff, and .1 .1 Mcííarr, J .1m. Chem Soc., 77, 335«, 1955. THE ( V A TJfl lil.'TH >S OF THE a-ff ELÌCA L COS FU H ItA'l'IOX TO THE OPTICAL HOT A Ti OS OF I'OLY/'E/'TI DES ASI) PROTEI SS* H y Ru i . D oty and K. 1). Lr\i>m.i«;t ( tununited hy (1 H. Kist/„lowAy, fared,., r,. IHM Shortly alter it was established that polypeptides could exist in solution as rigid, r«,M11sk«• «-helices as well as randomly coiled chains,' it became evident that the opti cal rotation of the helical form was substantially more positive than that of the randomly coiled form, l'or a while it seemed possible to explain this effect eithel as a result of the change in the environment of the optically active residues in the two configuration* or as arising from the existence of a single screw sense in the heli cal configurât ion which could then make a contribution to the optical rotation inde pendent of the contribution made by the optically active residues. Within the last year three different experiments have demonstrated that the stable helical configuration is exclusively of one screw sense, that is, right-handed or left-handed. In one experiment it was shown that the rotatory dispersion was normal for the randomly coiled configuration and abnormal for the helical form.■ This unusual effect could not arise simply from the changed environment of the optically active centers. In another experiment it was shown that the racemie polypeptide formed by using I, -polypeptide to initiate the polymerization of a D,L X -carboxyanhydride was itself optically active.* This showed clearly the preservation of at least some of the screw sense characteristic of the L-polypeptide in the grafted racemie poly peptide and the association of optical activity with the helical configuration. In a third experiment the optical rotation of a series of copolymers of i>- and L -residues was shown to increase linearly as the concentration of D-residues increased from zero to 10-30 per cent. 4 ' 5 Extrapolation from this linear region to 50 per cent n-resi- dues yielded a positive value which was an estimate of the optical rotation of a helix composed of racemie residues. As a consequence of these experiments, there re mains no doubt that the difference in rotation between the helical and randomly