Figure 2 .

Difference between the refined model and riding model of amide protons. (A) Deviations of hydrogen atoms from the peptide plane in single-acceptor hydrogen bond (left) and bifurcated hydrogen bond (right). The hydrogen omit nuclear density map is shown in magenta. The amide hydrogen atoms of riding models are shown in green. The distance between amide proton and oxygen atoms are shown in black. The angles of NH…O for experimentally determined models and riding models are shown in magenta and green, respectively. (B) Histogram of the frequency of differences in donor-hydrogen acceptor angles in single-acceptor hydrogen bonds between the experimentally refined model and the riding model. (This figure is modified from ref. [13].)