The Impact of Deep Eutectic Solvent on the Structural Stability of Myoglobin*

The stability of Myoglobin (Mb) in hydrated Deep Eutectic Solvent (DES) is investigated as a function of temperature and DES concentration. Determining the effect of DES on protein structure can lead to understanding the properties of DES, and allow their use to expand to cost-effective, and simple synthesis applications. Mb in 2 DESs: 35% wt glyceline-water and 5% wt reline-water and the resulting structure were compared to Mb in water. Small Angle X-ray Scattering results show that Mb’s tertiary structure remains relatively unchanged in both DESs until the temperature reaches 80^°C (for glyceline) and 70^oC (for reline) at which globular structure of Mb starts to gradually unfold. However, in water, Mb’s tertiary structure unfolds slowly and linearly with temperature until reaching a major transition at 80^°C. In addition, circular dichroism spectroscopy measurements show that Mb loses substantially more secondary structures with increased temperature in DES mixtures than in water solvent, yet DES allows better recovery of Mb secondary structure.