Invited Talk (I9)
9/3/2019, 10:45 am - 11:15 am in LH 108
Biman Jana
School of Chemical Science, IACS, Kolkata
E-mail:pcbj[at]iacs.res.in
Brief Bio-sketch:
Biman Jana has obtained his Ph.D. from IISc Bangalore in the year 2010. Then he did a postdoc with Prof. Jose Onuchic for 3 years and joined as an assistant professor at IACS in 2013. He is now an associate professor working in the field of theoretical biophysical/physical chemistry.
COMPOSITION DEPENDENT ANOMALIES AND ITS EFFECT ON PROTEIN STRUCTURE IN WATER-ALCOHOL BINARY MIXTURE
Aqueous binary mixtures have received immense attention in recent years because of their extensive application in several fields. Often it has been found that binary mixtures can alter the extent of hydrophobic interactions in proteins to a considerable extent. We have calculated the extent of pairwise hydrophobic interaction of simple model hydrophobes, in aqueous ethanolic mixture. Here, we have found that, pairwise hydrophobic interaction is enhanced up to xEtOH = 0.10, and afterwards it decreased. We have also connected this phenomenon to several structural and dynamical properties of water-ethanol binary mixtures. We have also demonstrated the effect of alcohol chain length on the pairwise hydrophobicity of simple pair hydrophobes in different water-alcohol composition. We found as the chain length of alcohol is increased from methanol (MeOH)→ethanol (EtOH)→propanol (PrOH)→butanol (BuOH), the extent of pairwise hydrophobicity changed significantly. The hydrophobic interaction is highest at xMeOH = 0.25 whereas it is highest at xBuOH = 0.03. We have related this anomalous behaviour to the composition dependent mixing enthalpies in different solutions. Next, we have reported the role of the hydrophilic amino acids behind ethanol induced unfolding of protein. Our results reveal that the weakening of hydrophobic interactions in aqueous ethanol solution along with larger preferential binding of ethanol to the unfolded state mediated by hydrophilic amino acids combinedly helps unfolding of protein in aqueous ethanol solution. We have also explored the composition dependent conformational landscape modulation for Cytochrome C. As a whole, our work may provide a general viewpoint towards the effect of water-alcohol binary mixture on the extent of pair hydrophobicity and protein folding.