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Figure 6.
Figure 6. Specific histone-histone interparticle
interactions in the NCP147 crystals. (a) Two adjacent
side-chains in the histone H4 N-terminal tail, H4-R23 and
H4-L22, and a Mn2+ ion (magenta) participate in extensive
interactions with a highly acidic region of the H2A-H2B dimer of
a neighboring nucleosome core. (b) (stereograph) A Mn2+ ion
(magenta) connects H3-D77 in the H3-H4 tetramer of one particle
with H2B-V45 in the H2A-H2B dimer of an adjacent particle. Both
of these amino acid residues enter the coordination sphere of
the divalent cation. The mean length over all six Mn2+-oxygen
bonds (magenta) is 2.25 Å. Hydrogen bonds made directly
between histone moieties (white) or via water molecules (yellow)
are shown. (c) (stereograph) The guanidinium group of H4-R23, in
a site adjacent to the Mn2+ ion of (b), makes four direct
hydrogen bonds to three surrounding side-chains of the
neighboring H2A-H2B dimer.
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