The thermodynamic basis of the mechanisms of bacterial virus infection
By using of differential scanning calorimetry (DSC) and temperature scanning rotational viscosimetry the specific phase transition we study in the heated suspensions of phages (Sd, DDVI) modeling the process of injection of the genetic material from the phage: the transition of interphage ds-DNA from the state of intramolecular liquid crystal into the coiled state of ds-DNA. The other conformational rearrangements represent the thermal denaturation of the coat proteins and helix-coil transition in DNA. We detect that: 1 ds-DNA output from the phage head (capsid), induced by temperature, not accompanied by any thermal (endo-or exo-) heat effects (temperature interval 48-60 8C; DSC sensitivity 0.4 mW/cm). 2 ds-DNA output from the capsid, increase of the suspension viscosity at least 100-times (!) and recent experiments reveal that it is not one-step process; we have at least two distinct phases of outlet of genetic material, manifesting, that there are strong interactions between the DNA sites and some proteins inside the capsid. It is not excluded that kinetic factors also regulate this ejection process. 3 According to our working hypothesis the main factors of the DNA condensation and packaging in viruse head and after its ejection through the hole with diameter close to ds- DNA's, are caused by the surrounded solution 'quality' and so-called 'hydration forces' between ds-DNA parallel packaged segments and, more exactly, by the difference of this parameters inside and outside the capsid of the phage.