Water in the hydrated protein powders: Dynamic and structure

It is not an understatement to say that the interplay between water and protein is a fundamental aspect of life. The vitality of an organism depends on the functionality of its biological machinery, and this, in turn, is mediated in water. Yet, we understand surprisingly little about the nature of the interface between bulk water and the protein. On the one hand, we know that the nature of the bulk water is dominated by the existence of H-bonding and H-bonded networks. On the other hand, the protein surface, where much of the bioactivity is centered, is a complex landscape of hydrophilic and hydrophobic elements. So how does the interface between these two entities work and how do they influence each other? The question is important because if one understands how a particular protein interface influences the dynamics of the water, it then becomes an easily accessible marker for similar behavior in other protein systems. The dielectric relaxation of hydrated proteins with different structures, lysozyme, collagen, and phycocyanin, has been reviewed in this paper. The dynamics of hydrated water was analyzed in terms of orientation and the ionic defect migration model. This approach enables to characterize the microscopic relaxation mechanism of the dynamics of hydration water on the different structures of the protein. In addition, our model is also capable of characterizing not only hydrated proteins but also polymer-water systems.