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added some nucleosome and acetylation counts
Some useful facts about DNA.
Some useful facts about DNA (taken from Wikipedia unless otherwise noted)
mass of DNA: 1 bp 660 Daltons (660 g/mol)
mass of DNA: 1 bp 660 Daltons (660 g/mol)
==Nucleosomes==
==Nucleosomes==
147 bp wrapped (1.67 left-handed superhelical turns) around histone octamer ( 2 copies each H2A, H2B, H3, and H4). The nucleosome contains over 120 direct protein-DNA interactions and several hundred water-mediated ones. Linker DNA between nucleosomes 10-80 bp
Approximately 30 million nucleosomes per human cell (~ 1 / 200 bp)
147 bp wrapped (1.67 left-handed superhelical turns) around histone octamer (2 copies each H2A, H2B, H3, and H4).
The nucleosome contains over 120 direct protein-DNA interactions and several hundred water-mediated ones.
Linker DNA between nucleosomes 10-80 bp
ideal MNase mononucleosomal digest -> 3 x 10<sup>7</sup> fragments per cell (3 x 10<sup>13</sup> for 1 million cells); if 4 x 10<sup>5</sup> transcription start sites (TSS), then ~ 0.1% of mononucleosomal fragments will be of interest.
Acetylation sites: "On average, 5 to 9 lysine residues of H2B, H3, and H4 were acetylated while a higher number (10 to 11 sites) of modifications was observed for H2A [but may be more]" PMID 37011222 ; so total of 50 - 76 acetylation sites per nucleosome.