Six 2-dimensional projections of the 4-distance distribution for the Asn-Gln pair. Interaction between Asn and Gln is defined by four distances between OD1, ND2 atoms of Asn and OE1, NE2 atoms of Gln. The 4-distance data for Asn-Gln were collected from high-resolution protein structures (see Methods for details) and are displayed in six 2-dimensional projections. Each projection represents mutual distribution of two particular distances. The peaks in distributions indicate preferred mutual arrangements of atoms under consideration. The histograms were built with a bin size of 0.25 Å without smoothing. The histograms are represented as contour plots generated with MATLAB.