Microcalorimetric Study of the Effect of Hexa-histidine Tag and Denaturant on the Interaction Mechanism between Protein and Metal-Chelating Gel

✍ Scribed by Fu-Yung Lin; Wen-Yih Chen; Hsiu-Mei Chen

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 87 KB
• Volume: 238
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.7526

✦ Synopsis

A recombinant protein, Schistosoma japonicum glutathione-Stransferase (SjGST), was fused with a C-terminal hexa-histidine tag to obtain SjGST/His. Both proteins were used to probe the interaction mechanisms with the metal ions immobilized on chromatography gels. Isothermal titration calorimetry was used to directly measure the adsorption enthalpies ( H ads ) of both proteins with Ni-NTA and TALON (Co 2+ ) commercial affinity resins, under the conditions of with and without the presence of a denaturant. The result reveals that SjGST/His had a lower H ads value with Ni-NTA than did SjGST, mainly attributed to the formation of more coordination bonds with or a stronger binding with Ni-NTA. Furthermore, the difference between the H ads values of SjGST/His onto TALON under the nature and denaturing conditions were insignificant, implying that the binding topography of the hexa-histidine tail with immobilized Co 2+ was not significantly changed with the presence of a denaturant. In addition, this study shows that the proposed binding models and the directly measured adsorption heat can be combined to elucidate the difference in the interaction mechanisms of SjGST/His adsorption onto those two adsorbents from a thermodynamic perspective.