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Figure 3
Schematic statistics of hydrogen bonds. Acceptor positions (Y) are searched and plotted in the first zone. In this example, hydrogen-bond lengths are defined by XY values less than 2.7, 2.6 and 3.1 Å for the acceptor atoms, N, O and S, respectively, and hydrogen-bond angles are defined to be the supplement of 180°. These cut-off values (2.7, 2.6 and 3.1 Å) are just defaults and users can modify them. Note the very surprising result that in proteins there are very few acceptor atoms which form truly collinear X—H⋯Y hydrogen bonds, in contrast to the situation in small inorganic and organic compounds in which linear hydrogen bonds are quite common. (Note: the word `others' on the right-hand side of this plot refers to entities other than protein residues or water molecules, such as heme groups, substrates, counterions etc.)

ISSN: 2053-2733
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