[Text]

Date:
1961
Reference:
PP/CRI/H/2/20/1
Catalogue details

Licence: In copyright

Credit: [Text]. Source: Wellcome Collection.

    1/160
    Introduction In this paper we shall describe in detail our work on the structure of collagen which we have already outlined elsewhere (Rich and Crick, 1955). Tfc-i-e work Is still unfinished but sufficient Tprnc-rws s has bee n made -to .1ua4^*y-'tHrty~±r»terlm report. The main sustance of the paper is (1) our demonstration that, Kiven certain assumptions, only L <* (¡y CLKm~ f f-xpr • two^ir+daifc for cotiaseen- (2) our detailed work on the co-ordinates and Fourier transforms of one of these models (Collagen II), ^ ftpinflay tf> Cv-^ ¡k< A ^ . In addition we report preliminary work on the other álternative2 ■ Previous ìork The fact that collagen *ives a distinct I -ray pattern has been known since the 1920's. The main features are a strong /I /->4 meridional spacin* of 2.86 A and an equatorial spacing of *0 to which varies with humidity. le shall not discuss the earlier 'Î ' ■? models (see the reviews bv. Bear and Xendrew) which assumed that the structure consisted of sheets of chains. The first suggestion that the structure mi<?ht be helical was due to Paulin* and Corey{¡(j ) who proposed a structure (now withdrawn) having three chains helically intertwined. The major advance, however, was the recognition of the correct non-integer screw axis by Cohen aj»d Bear^ and by Cowan, Nor^h and Randall. The latter workers obtained a *rafctly improved X -ray diffraction pattern bv keeping the specimen stretched during the I -ray exposure, and this has made it much easier to recognise the helical nature of the structure. The next important advance was made by Ramachandran and Kartha-. The two structures they proposed are not correct but they