Nucleosome core particle, schematic

Fig. 5. Schematic model of the nucleosome, with histone HI shown as stabilizing the fold of the DNA molecule around the core histones [based on results of Sperling and Sperling (1978)]. The nucleosome dimensions are derived from X-ray (Finch et al., 1977) and neutron (Baldwin et al., 1975 Pardon et al., 1977 Suauet al., 1977) scattering experiments. The histone core dimensions are derived from electron microscopic and X-ray studies (Sperling and Amos, 1977 Wachtel and Sperling, 1979 Sperling and Wachtel, 1979). The regions of the DNA molecule indicated by dashed lines indicate those base pairs which are not present in nucleosome core particles.

Fig. 6. (a) A schematic model of the helical, double-stranded, unstaggered, H4 fiber (Sperling and Amos, 1977). The asymmetric unit is an axial dimer and there are six such dimers per strand per repeat. The repeat distance is 330 A. The two different types of axial bonds—within and between dimers—are denoted by a thick and thin line, respectively. The tetrameric grouping is indicated, (b) A model of (a) upon which is superimposed a schematic representation of a nucleosome core particle... 

The major structural effects of histone acetylation that affect both the nucleosome core particle and the chromatin fiber are schematically summarized in Fig. 13. 

Figure 31.16. Nucleosome Core Particle. The structure consists of a core of eight histone proteins surrounded by DNA. (A) A view showing the DNA wrapping around the histone core. (B) A view related to that in part A by a 90-degree rotation shows that the DNA forms a left-handed superhelix as it wraps around the core. (C) A schematic...

FIGURE 8 The histone tails shown schematically to their full predicted length in relation to the nucleosome core particle (drawn to scale). 

The nucleosome core fragment (771 is composed of duplex DNA wound in a left handed helix around a cental protein core. A typical core fragment has about 145 base pairs of duplex DNA forming about 1.75 superhelical turns. Measurements of the overall dimensions of the core fragment indicate that there is very little space between adjacent wraps of the duplex. A side view of a schematic of core particle is shown in Fig. 2. 

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