Crystal Structure Elucidation by the Crystal Data Centre

Abstract

KNOWLEDGE of the preferred conformation of chemical groups has been shown to be essential for the determination of the structures of biological molecules. The prime example is the elucidation of the structure of the α-helix for protein molecules by Pauling, Corey and Branson¹ from knowledge that the peptide group is coplanar and the importance of the hydrogen bond, whereas others had proposed incorrect structures owing to lack of this knowledge. On a more complicated scale, because the energy stabilizing the preferred conformation is less, but on an important biological scale, it was pointed out by Canepa, Pauling and Sörum² that the N⁺–C–C–O– group is synclinal. This was shown more clearly by Sundaralingam³ and recently shown to be true in solution by Partington, Feeney and Burgen⁴. The conformation of this group is of great importance in nervous transmitter substances⁵ and in phospholipids.