Posts Tagged ‘search above’

The conformational preference of s-cis amides. Ramachandran plots.

Monday, February 11th, 2013
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This is really just a postscript to the previous post. There I showed how a search of the (small molecule) crystal database revealed the s-cis conformation about the N-C amide bond (the one with partial double bond character that prevents rotation) and how this conformation means that a C-H approaches quite closely to an adjacent oxygen. It is a tiny step from that search to a related, and very famous one named after Ramachandran[1]. Indeed this search, and the contour map used to display the results, really put crystal databases on the map so to speak.



  1. G. Ramachandran, C. Ramakrishnan, and V. Sasisekharan, "Stereochemistry of polypeptide chain configurations", Journal of Molecular Biology, vol. 7, pp. 95-99, 1963.