(284j) Modeling Biorelevant Systems

Biorelevant systems are complex, aqueous systems, which's properties and even function depend on various parameters, such as temperature, concentration and pH. They usually contain a whole variety of substances, such as amino acids, peptides and proteins, osmolytes, salts or even polyelectrolytes. Knowing the thermodynamic properties of these systems is crucial for exploring reaction pathways and designing product-separation steps in down-stream processing. The properties which are of particular interest are the activity coefficients of the various components, osmotic coefficients and solubilities.

The talk gives first an overview about the thermodynamic modelling of biorelevant systems. Exemplarily, amino-acid systems as function of added salts and pH will be considered. Experimental data as well as modelling results reveal that not only the concentration (ionic strength) but also the kind of salt strongly influences the solution properties (salting-in/salting-out effects). Moreover, as crystallisation is an important separation step, the solubility of one amino acid as influenced by the presence of other biomolecules (e.g. other amino acids) and their modelling will be discussed.

Microorganisms living under high pressure often form so-called compatible solutes (osmolytes) to sustain the osmotic pressure. In the second part of this talk we talk will present new experimental data for osmolyte systems (e.g. ectoin) and demonstrate how thermodynamics can be used to understand the different effect of osmolytes in comparison to that of salts.