Mineral-associated proteins have been proposed to play a central role not only in assisting the growth of biomineral crystals in hard tissues but also in preventing or limiting mineral formation in soft tissues. The elucidation of protein-biomineral interactions may lead to the design of mineralized tissues with novel properties and most importantly the development of therapies for common diseases such as kidney stones calcification in blood vessels osteoporosis etc. However the mechanism of the interaction at this unique organic-inorganic interface is still poorly understood. X-ray crystallography techniques have provided important information on the adsorbed states. Unfortunately these methods have limitations in determining the driving forces of the adsorption and the underlying roles played by the lattice ions and ionic solutions. We employ all-atom enhanced-sampling simulations and free-energy calculation techniques to characterize these interactions with the final goal of designing proteins with improved adsorption properties and capacity to prevent or enhance crystal growth.