Ramachandran outlier

The Ramachandran Plot was described on 1963 by Ramachandran, G.N.; Ramakrishnan, C.; Sasisekharan, V. ^[1]. See Dihedral/Index for explanations.

Ramachandran outliers are those amino acids with non-favorable dihedral angles, and the Ramachandran plot is a powerful tool for making those evident. Most of the time, Ramachandran outliers are a consequence of mistakes during the data processing.

However, sometimes Ramachandran outliers might play a special role in function. See for example the case of Ser-200 in the structure 1ea5. Let's draw its Ramachandran Plot.

The following green links require that you first click the above green link to Ramachandran Plot.

Notice that the residues in beta sheets are colored in yellow, the residues in alpha helix colored in magenta, beta turn in blue and others in white. At any time you may display all residues.

Only Gly are allowed in the lower right quarter. If we hide Gly from the plot, we will find the Ser 200, with phi/psi angles considered non-favourable for Serine.

However, in this case, a Ramachandran-misplaced residue (Ser 200) seems to play an important role in the function of this structure, a member of the alpha/beta hydrolase fold ^[2].