Abstract-Collective Hydration Dynamics of Guanidinium Chloride Solutions and its Possible Role in Protein Denaturation: A Terahertz Spectroscopic Study

Nirnay Samanta,   Debasish Das Mahanta and   Rajib K Mitra  

Phys. Chem. Chem. Phys., 2014, Accepted Manuscript

DOI: 10.1039/C4CP03273J
Received 23 Jul 2014, Accepted 08 Sep 2014
First published online 09 Sep 2014

http://pubs.rsc.org/en/content/articlelanding/2014/cp/c4cp03273j#!divAbstract

The remarkable protein denaturation ability of guanidinium chloride (GdmCl) is a well studied and yet controversial phenomenon; the exact molecular mechanism is still debatable; specially the role of hydration dynamics has been offered less attention. In the present contribution we have tried to addressed the issue that whether the collective hydrogen bond dynamics of water gets perturbed in presence of GdmCl and its possible impact on the denaturation of a globular protein human serum albumin (HSA) using terahertz (THz) time domain spectroscopy (TTDS) in the frequency range of 0.3-2.0 THz. The collective hydrogen bond dynamics is determined by fitting the obtained complex dielectric response in a multiple Debye relaxation model. To compare the results, the studies have been extended to two more salts: tetramethylguanidinium chloride (TMGdmCl) and sodium chloride (NaCl). It has been concluded that the change in the hydration dynamics plays a definite role during the protein denaturation process.