Figure 1: Density plot of distribution of all hydrogen bond rotations in PDB-HQ60.
From: Hydrogen bond rotations as a uniform structural tool for analyzing protein architecture
(a) Hydrogen bond from peptide units Pi to peptide unit Pj, where the locations of the backbone atoms 
, Ci and Ni+1 (
, Cj and Nj+1) determine a rotation 
. Rotation of both peptide units by the inverse of 
brings Pi in standard position, 
and Pj to a new position 
and the rotation bringing 
to 
is the rotation 
associated to the hydrogen bond. The blue arrow from the center of mass of 
to 
is the translation associated to the hydrogen bond. (b) 3D rendering of the total distribution coloured by density. (c) Orthoscopic projection of the density plot in the x–y plane. (d) Orthoscopic projection of the density plot in the x–z plane.
