화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.114, No.31, 10171-10175, 2010
Amino Acid Behavior in Aqueous Denaturant Solutions: Temperature Dependence of the L-Histidine-Amide Interaction
We have studied the thermodynamics of the pair interaction between aromatic amino acid-L-histidine and nonelectrolyte denaturing globular proteins-hydrophilic urea (U) and presumably hydrophobic dimethylformamide (DMF) in the temperature range of 288-328 K. Our study does indicate for the first time the anomalous temperature dependence of the enthalpies and entropies of the L-histidine-U and L-histidine-DMF interaction in water, which is consistent with the previously reported results for water-urea (U) and water-U-L-phenylalanine systems. This phenomenon is found to be closely related to the behavior of water, since in all cases, the extrema observed arise in the temperature range of 300-308 K, where the temperature dependence of the heat capacity of pure water passes through the minimum The amino acid-urea interaction is shown to be accompanied in a wide temperature range by a large negative enthalpy change, which reveals a strong tendency of urea binding with polar and charged groups of proteins.