Selection by site-directed antibodies of small regions of peptides which are ordered in water.

High resolution nuclear magnetic resonance has been used to study a short peptide which corresponds to the antigenic region of a larger peptide immunogen. This work shows that there is a strong conformational preference for a Type II beta-turn in solution. This observation has implications for the nature of the immunogenicity and antigenicity of peptide antigens as well as for the more general question of protein-folding mechanisms.