ISSN:
0887-3585
Keywords:
protein-saccharide interactions
;
isothermal titration calorimetry
;
binding and dehydration energetics
;
molecular interactions in vacuum
;
hydrogen bonds
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Isothermal titration calorimetry was used to characterize thermodynamically the association of hevein, a lectin from the rubber tree latex, with the dimer and trimer of N-acetylglucosamine (GlcNAc). Considering the changes in polar and apolar accessible surface areas due to complex formation, we found that the experimental binding heat capacities can be reproduced adequately by means of parameters used in protein-unfolding studies. The same conclusion applies to the association of the lectin concanavalin A with methyl-α-mannopyranoside. When reduced by the polar area change, binding enthalpy values show a minimal dispersion around 100°C. These findings resemble the convergence observed in protein-folding events; however, the average of reduced enthalpies for lectin-carbohydrate associations is largely higher than that for the folding of proteins. Analysis of hydrogen bonds present at lectin-carbohydrate interfaces revealed geometries closer to ideal values than those observed in protein structures. Thus, the formation of more energetic hydrogen bonds might well explain the high association enthalpies of lectin-carbohydrate systems. We also have calculated the energy associated with the desolvation of the contact zones in the binding molecules and from it the binding enthalpy in vacuum. This latter resulted 20% larger than the interaction energy derived from the use of potential energy functions. Proteins 29:467-477, 1997. © 1997 Wiley-Liss, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
