Using a combination of one- and two-dimensional methods, 1H- and 15N-nmr spectroscopy has been employed to perform the complete assignment and the structural determination of the immunogenic undecapeptide CTTTNSRGTTT in DMSO solution. Nuclear Overhauser enhancement spectroscopy experiments indicated the presence of secondary structures, mainly turn-like structures, which only represent a family, albeit a dominant one, of an ensemble of conformations available to the peptide. Since reverse turns may play an important role as intermediates in protein folding, the experimental observations described here may link the immunological and theoretical approaches to protein folding.