The way in which biomacromolecules behave in concentrated solutions depends primarily on their structure and the kinds of their interactions. On the other hand, properties in sufficiently dilute solution depend primarily, and are a source of information, on their structure. Furthermore, the concentration dependence of the properties in the dilute regime is an indicator of the interactions that will determine their behaviour in more concentrated solutions. In this communication I shall present an overview of the the essential concepts, theories and computational approaches for predicting or analyzing dilute-solution properties, like the hydrodynamic coefficients for diffusion, sedimentation and viscosity, and the radius of gyration.

Predicting dilute-solution properties from structure was made in classical biophysics in terms of simple models like random coils for flexible particles, and ellipsoids or rods for flexible ones. Nowadays, such prediction is possible for rigid arbitrarily shaped structures – even with atomic or high-resolution detail, and arbitrarily flexible particles, thanks to recent advances in theory that have been implemented in public-domain, easy-to-use computational tools. Other tools are available for the inverse problem of determining structural information from the properties.

Some properties that reflect the intermolecular interactions in semi-dilute solution that will be determining the concentrated regime are easily available from experiments and/or predicted from structure. Examples are the covolume, that determines the size/shape contribution to the second virial coefficient, and the Huggins constant that measures the concentration dependence of the solution viscosity beyond the very-diluted regime

Supported by Grupos de Excelencia de la Región de Murcia (grant 04531/GERM/06) and grant CTQ2012-33717 from Ministerio de Economia y Competetitividad, including FEDER funds.

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