January 2011 issue
Cover illustration: Data on this per-4-nitrobenzoyl bile acid derivative was collected with synchrotron radiation and allowed the determination of the absolute structure. The two symmetry-independent disulfide molecules in the asymmetric unit with their centrally placed disulfide bridges exhibit different helicity as shown by the C-S-S-C torsion angles of 71.0 (1) and -92.5 (1)°. The two molecules intertwine to form a tight dimer as shown here. See Brzezinski, Tomkiel, Lotowski, Morzycki & Dauter [Acta Cryst. (2011). E67, o75-o75].