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. Author manuscript; available in PMC: 2018 Apr 19.
Published in final edited form as: Nature. 2017 Mar 29;543(7647):637–646. doi: 10.1038/nature21701

Figure 5. Examples of cation–π interactions.

Figure 5

a, Left, depiction of the aromatic box in the HP1 chromodomain binding trimethyllysine (KMe3) of histone 3 (H3: Y, tyrosine; W, tryptophan). Green, HP1 chromodomain carbon; blue, nitrogen; red, oxygen; black, H3 carbon. Right, binding of HP1 chromodomain to wild-type H3 (unmodified) and a series of mutants (tBuNle9, tert-butyl norleucine; K9Me1, methyllysine; K9Me2, dimethyllysine; K9Me3 trimethyllysine). Reprinted from ref. 52, National Academy of Sciences, USA. b, Proposed mechanism for hopene synthesis from squalene. c, Nucleophilic ring opening of episulfonium ions is stabilized by a cation–π interaction: top, reaction; middle, transition state; bottom, effect of catalyst substituents on product enantiomeric excess.