Practice question

Bending rigid DNA duplex around small histone octamer radius about 4.2 nanometers overcomes electrostatic repulsion and mechanical stiffness. Strong driving force arises from extensive attractive interactions between positively charged lysine and arginine side chains lining histone octamer superhelical ramp and negatively charged phosphate groups, plus multitude hydrogen bonds between histone main chain amides and DNA backbone phosphates and numerous water-mediated contacts. Charge neutralization lowers energetic barrier permitting sharp curvature. Hydrophobic interactions stabilize octamer core internal assembly, but DNA-histone attraction via electrostatics and hydrogen bonding governs bending energetics, not covalent bonds or dispersive forces alone.