Kinetic analysis of the effect of poliovirus receptor on viral uncoating: the receptor as a catalyst

We examined the role of soluble poliovirus receptor on the transition of na tive poliovirus (160S or N particle) to an infectious intermediate (135S or A particle). The viral receptor behaves as a classic transition state theo ry catalyst, facilitating the N-to-A conversion by lowering the activation energy for the process by 50 kcal/mol, in contrast to earlier studies which demonstrated that capsid-binding drugs inhibit thermally mediated N-to-A c onversion through entropic stabilization alone, capsid-binding drugs are sh own to inhibit receptor-mediated N-to-A conversion through a combination of enthalpic and entropic effects.