In contrast to the nucleosome, H3 N-tail acetylation and dynamics are greatly suppressed in the NCP regardless of H4 N-tail acetylation because the H3 N-tail is strongly bound between two DNA gyres. In the chromatosome, the asymmetric H3 N-tail adopts two conformations: one contacts two DNA gyres, as in the NCP; and one contacts linker DNA, as in the nucleosome. However, the rate of H3 N-tail acetylation is similar in the chromatosome and nucleosome. Thus, linker DNA and linker histone both regulate H3-tail dynamics and acetylation. 

NMR experiments were performed on AVANCE 600-MHz and AVANCE III HD 950-MHz spectrometers with a triple-resonance TCI cryogenic probe (Bruker Bio Spin) at 298 K using 110 uM samples dissolved in 25 mM MES (pH 6.0), 25mM NaCl, 2 mM DTT, and 5% D2O. Three-dimensional transverse relaxation optimized spectroscopy (TROSY) of HNCO, HN(CA)CO, HNCA, HN(CO)CA, HNCACB, and HN(CO)CACB was used to obtain sequential assignments of the backbone 1H, 13C, and 15N chemical shifts of the H3 and H4 N-tails in the nucleosome.