To be or not to be (bound): Impact of ligand binding on galectin-1 structure and thermal stability

DI LELLA, SANTIAGO; MARTÍ, MARCELO ADRIÁN; DÍAZ RICCI, JUAN CARLOS; ESTRIN, DARÍO ARIEL

Sanibel Island, Georgia, Estados Unidos

Simposio; 49th Sanibel Symposium; 2009

Quantum Theory Project - University of Florida, EE.UU.

The stability of proteins involves a critical balance between interactions of different order ofmagnitude. Based on previous experimental evidence of an increased thermal stabilitygained in galectin-1 (a β-galactosyl terminal binding lectin involved in the immuneresponse) upon binding to the lactose disaccharide, in this work we analyze the structuralchanges occurring upon binding, and thermal denaturation of the protein and the complex.Using an approach that provides insight into the molecular determinants of the observedphenomenum, molecular dynamics simulations were carried out followed by a detailedcomputation of thermodynamic properties: internal energy, solvation free energy, andconformational entropy. The energetic profile of the binding process is also presented.Our results show that while the ligand (lactose) binding do not alter galectin-1 structuresignificantly, changes in the flexibility of different regions and internal energy of the proteincan be attributed to the binding, conferring the protein an increased thermal stability. Adiscussion of the main factors involved in the increased stability of the protein ispresented.