Studies on thermodynamic aspects of protein denaturation with the aim of obtaining additional information regarding protein structure-function relationship. Protein denaturation is done in many ways including thermal denaturation, chemical denaturation (by urea or guanidine hydrochloride), solvent denaturation, salt denaturation and interaction of proteins with surfactants. Different techniques such as equilibrium dialysis, isothermal titration microcalorimetry, differential scanning calorimetry, spectroscopy and densiometry are used for this purpose. Also kinetics of activation and inactivation of enzymes attached to ligands (inhibitor, activator, denaturant) and comparative studies related to kinetic and thermodynamic parameter involved.
A brief review of a representative project
A new equation with a useful simple graphical method, very similar to the Scatchard plot (heat divided by ligand concentration versus heat) was introduced to obtain the equilibrium constant and the enthalpy of binding using isothermal titration calorimetry (ITC) data for a set of independent binding sites. The equilibrium constant and molar enthalpy of binding measured by a linear pseudo-Scatchard of calorimetric data for a system with a set of independent binding sites (such as binding fluoride ions on urease and monosaccharide methyl -D-mannopyranoside on concavalin-A) was remarkably like that obtained from a normal fitting Wiseman method and other our technical methods. On applying this pseudo-Scatchard graphical method to study the binding of copper ion on myelin basic protein (MBP), a concave downward curve obtained was consistent with the positive cooperativity in the binding. A graphical fitting simple method for determination of thermodynamic parameters was also introduced. This method is general, without any assumption and restriction made in previous method. This general method was applied to the binding of cyanide ion on catalase and product inhibition study of adenosine deaminase and carbonic anhydrase.