Methodology Structural data of NCPs The experimental database is constructed by collecting 6870 base pair steps from 48 nucleosome crystal structures in the Protein Data Bank (PDB), including 1AOI, 1E... Z, 1F66, 1ID3, 1KX5, 1KX4, 1KX3, 1M1A, 1M19, 1M18, 1P3P, 1P3O, 1P3M, 1P3L, 1P3K, 1P3I, 1P3G, 1P3F, 1P3B, 1P3A, 1P34, 1S32, 2CV5, 1U35, 1ZLA, 2F8N, 2FJ7, 2NZD, 2NQB, 2PYO, 3B6G, 3B6F, 3C1C, 3C1B, 3KUY, 3LJA, 3KWQ, 3LEL, 3AFA, 3A6N, 3MGS, 3MGR, 3MGQ, 3MGP, 3KXB, 3MVD, 3LZ0 and 3LZ1.