The effects of pH and ligand binding on the stability of abrin II, a heterodimeric ribosome-inactivating protein, and its subunits have been studied using high-sensitivity differential scanning calorimetry. At pH7.2, the calorimetric scan consists of two transitions, which correspond to the B-subunit [transition temperature (Tm) 319.2K] and the A-subunit (Tm 324.6K) of abrin II, as also confirm...

Within the past 10 years, major advances in the design and development of differential scanning calorimeters (DSC) (1) and isothermal titration calorimeters (ITC) (2) have resulted in an unparalleled level of sensitivity, stability, and reproducibility in calorimetric measurements of large molecules. These improvements have allowed the thermal stability and ligand binding processes of biologica...

BioTechniques 885 During the last 15 years isothermal titration calorimetry (ITC) has come of age. There are now in excess of 2000 instruments sited in laboratories in more than 40 countries around the world. Research scientists in such diverse fields as biophysics, cell biology, pharmaceutical screening, and food research routinely investigate their systems of interest using ITC. Why is it tha...

Cyclam was attached to 1-, 2- and 3-pyrrole lexitropsins for the first time through a synthetically facile copper-catalyzed "click" reaction. The corresponding copper and zinc complexes were synthesized and characterized. The ligand and its complexes bound AT-rich DNA selectively over GC-rich DNA, and the thermodynamic profile of the binding was evaluated by isothermal titration calorimetry. Th...

Complexation of chlorogenic acid (CA) by b-cyclodextrin (b-CD) at mildly acidic pH, was studied by fluorescence spectroscopy, isothermal titration calorimetry (ITC), cyclic voltammetry (CV) and NMR spectroscopy. Thermodynamic parameters (DH°, DS° and K) determined by both fluorescence and ITC, showed that the complexation of CA by b-CD is an enthalpy-driven process. Results show that CA molecul...

We describe here the synthesis and characterization of a molecular receptor that forms kinetically and thermodynamically stable host-guest complexes in water. This cavitand-based host is composed of a preorganized aromatic pocket whose rim is decorated with four negatively charged carboxylate groups. (1)H NMR and isothermal titration calorimetry have been used to characterize the behavior of th...

We have investigated the interaction of peptides containing phosphohistidine analogues and their homologues with the prototypical phosphotyrosine binding SH2 domain from the eukaryotic cell signalling protein Grb2 by using a combination of isothermal titration calorimetry and a fluorescence anisotropy competition assay. These investigations demonstrated that the triazole class of phosphohistidi...

Ion exchange chromatography is a widely used method for purification of all types biomolecules in current biotechnological downstream processes. Knowledge on the binding behavior proteins provides valuable insight understanding molecular mechanisms protein interactions biological context. However, thermodynamic parameters such as enthalpy and entropy changes that characterize adsorption are sti...

Effects of ?-cyclodextrin, ?CD, on refolding of lysozyme was investigated at pH 12 employing isothermal titration calorimetry (ITC) at 300K in 30mM Tris buffer solution. ?CD was employed as an anti-aggregation agent and the heats obtained for lysozyme+?CD interactions are reported and analyzed in terms of the extended solvation model. It was indicated that there are two sets of identical and no...