THE RAMACHANDRAN PLOT AND PROTEIN STRUCTURE VALIDATION

The Ramachandran plot has been the mainstay of protein structure validation for many years. Its detailed structure has been continually analysed and refined as more and more experimentally determined models of protein 3D structures have become available, particularly at high and ultra-high resolution. As more data has accumulated, so the differences in the plot for different amino acids, and with different residue neighbours, or in different structural contexts, have become apparent. Validation software has had to adapt to these subtle changes and a single Ramachandran plot can no longer accurately depict ‘favourable’ and ‘disallowed’ regions for all amino acid types.