Refolding of urea-induced denaturation of model proteins by trimethylamine N-oxide

摘要

The biomolecules are known to be stabilized by osmolytes, trimethylamine-N-oxide (TMAO) while urea, destabilizes the protein structures. The deleterious effect of urea on proteins has been counteracted by TMAO is well understood; nonetheless, refolding of urea-induced conformational changes of proteins by TMAO is still an active subject. To understand the refolding ability of TMAO from urea-induced denaturation of biomolecules, we have performed transfer free energy (ΔG′_(tr)) and the hydrodynamic diameter (d_H) of cyclic dipeptides (CDs) such as, cyclo(Gly-Gly), and cyclo(Leu-Ala) through solubilities and dynamic light scattering (DLS) measurements, respectively. We observed positive and negative values of ΔG′_(tr) for CDs from water to TMAO and urea, respectively. Our results reveal that TMAO is a refolding additive for urea deleterious actions on CDs at 1:1 and 1:2 molar ratios of TMAO and urea. However, TMAO (1 M) fails to refolding CDs structure from the urea (3-5 M)-induced conformational changes on CDs.