Theoretical model of DNA packing in the phage head

A statistical-physical model of the packing of bihelical DNA in the capsid of the icosahedral bacteriophage is proposed, interpreting the intraphage DNA as a globule - an intramolecular liquid crystal. From analysis of the free energy of the system it is concluded that the processes of the entry-exit of DNA are possible under the influence of change in solvent within and outside the phage or on the size of the head. It has been established that the process proceeds without thermal effects (not by the all-or-none principle), the intermediate states with DNA partially released and partially held in the capsid possibly being in equilibrium. The role of the interaction of DNA with the inner wall of the capsid is considered. The considerable possibilities of the model for the qualitative explanation of the published experimental data are demonstrated.