Protein association investigated by THz spectroscopy and molecular modeling

摘要

Macromolecular crowding is a common intracellular phenomenon that causes conformational changes of proteins and protein association. We investigated these macromolecular crowding effects on a highly concentrated BSA solution using THz spectroscopy and molecular modeling. We modeled several BSA 50% w/w solutions comprising two BSA molecules in a water box and selected a single model based on the agreement with THz experiments. We further modeled BSA association at concentrations higher than 50% w/w and selected a possible dimer model based on the strength of the interaction between the two proteins. The flexibility of the BSA dimer was compared with the flexibility of BSA from the solution. Monomeric BSA from the solution model presents mobile regions scattered through all the structure, with differences of disposition and extent between the two molecules. Dimerization changes BSA flexibility, as the two molecules from the dimer present compact regions of both high flexibility and low flexibility. The low flexibility regions include their interaction sites.