Thermodynamic analyses reveal role of water release in epitope recognition by a monoclonal antibody against the human guanylyl cyclase C receptor

Swaminathan, Chittoor P. ; Nandi, Animesh ; Visweswariah, Sandhya S. ; Surolia, Avadhesha (1999) Thermodynamic analyses reveal role of water release in epitope recognition by a monoclonal antibody against the human guanylyl cyclase C receptor Journal of Biological Chemistry, 274 (44). pp. 31272-31278. ISSN 0021-9258

Full text not available from this repository.

Official URL: http://www.jbc.org/content/274/44/31272.short

Related URL: http://dx.doi.org/10.1074/jbc.274.44.31272

Abstract

The thermodynamics of a monoclonal antibody (mAb)-peptide interaction have been characterized by isothermal titration microcalorimetry. GCC:B10 mAb, generated against human guanylyl cyclase C, a membrane-associated receptor and a potential marker for metastatic colon cancer, recognizes the cognate peptide epitope HIPPENIFPLE and its two contiguous mimotopes, HIPPEN and ENIFPLE, specifically and reversibly. The exothermic binding reactions between 6.4 and 42°C are driven by dominant favorable enthalpic contributions between 20 and 42°C, with a large negative heat capacity (ΔCp) of −421±27 cal mol−1 K−1. The unfavorable negative value of entropy (ΔSb0) at 25°C, an unusual feature among protein-protein interactions, becomes a positive one below an inversion temperature of 20.5°C. Enthalpy-entropy compensation due to solvent reorganization accounts for an essentially unchanged free energy of interaction (ΔΔGb0≅0). The role of water molecules in the recognition process was tested by coupling an osmotic stress technique with isothermal titration microcalorimetry. The results provide direct and compelling evidence that GCC :B10 mAb recognizes the peptides HIPPENIFPLE, HIPPEN, and ENIFPLE differentially, with a concomitant release of variable and nonadditive numbers of water molecules (15, 7, and 3, respectively) from the vicinity of the binding site.

Item Type:Article
Source:Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
ID Code:55345
Deposited On:18 Aug 2011 12:02
Last Modified:09 Oct 2011 07:56

Repository Staff Only: item control page