Figure 5. Structural representations of cycloviolacin O14.

(A) Stereo-view of the 20 lowest energy structures of cycloviolacin O14 superimposed over the backbone atoms (N, C and C^α). The backbone is in black with the disulfide bonds in grey. Loop 2 of O14 (residues 10–14) is disordered due to peak broadening and a lack of restraint data in this region. (B) Schematic diagram of the secondary structure of cycloviolacin O14 showing the inter-strand NOEs as continuous arrows or thick lines and hydrogen bonds as broken lines. Sequential NOEs are omitted for clarity. Hydrogen bonds were inferred from slow-exchange data, sensitivity of amide chemical shifts to changes in temperature and preliminary structure calculations, as described in the text.