Role of Aqueous Media in Macromolecular Crowding

The behavior of biomolecules in a crowded environment is affected by a number of factors, with the excluded volume being traditionally considered as a major contributor to the macromolecular crowding effects in polymer solutions. In addition to the hard nonspecific steric interactions representing the excluded volume effects, other commonly considered factors are the so-called soft interactions between the crowder and the crowdee, such as electrostatic, hydrophobic, and van der Waals interactions. However, the changes in the solvent properties of aqueous media induced by the crowding agents may represent important but commonly neglected factor affecting behavior of biomolecules in a crowded environment. This chapter systematically represents information in support to this hypothesis. Presented data clearly show that the crowding agents do induce changes in solvent properties of aqueous media in crowded environment. Therefore, these changes should be taken into account for crowding effect analysis.