Entropy and Volume Change of Dissociation in Tobacco Mosaic Virus Probed by High Pressure

Virus dissociation and inactivation by high pressure have been extensively studied in recent decades. Pressure-induced dissociation of viral particles involves a reduction in the Gibbs free energy of dissociation and a negative change in volume. In this work, we investigated the combined effect of high pressure and temperature on the dissociation of tobacco mosaic virus (TMV). We assumed the presence of two states of TMV with different tendencies to dissociate. Thus one form presents a low tendency (L) and the other a high tendency (H) to dissociate. Based on the model described here, the L–H transition was favored by an increase in pressure and a decrease in temperature. The volume change of dissociation was pressure- and temperature-dependent, with a highly negative value of −80 mL/mol being recorded at 0 °C and atmospheric pressure. The entropy and enthalpy of dissociation were very temperature- and pressure-dependent, with values of entropy of 450 to −1300 kJ/mol and values of enthalpy of 5.5 × 104 to 2.4 × 104 kJ/mol. The dissociation of TMV was enthalpy-driven at all temperatures and pressures investigated. Based on these findings, we conclude that the model presented allows accurate predictions of viral dissociation behavior in different experimental conditions.