Enthalpic Forces Correlate with the Selectivity of Transthyretin-Stabilizing Ligands in Human Plasma.
Iakovleva, I., Brannstrom, K., Nilsson, L., Gharibyan, A.L., Begum, A., Anan, I., Walfridsson, M., Sauer-Eriksson, A.E., Olofsson, A.(2015) J Med Chem 58: 6507-6515
- PubMed: 26214366 
- DOI: https://doi.org/10.1021/acs.jmedchem.5b00544
- Primary Citation of Related Structures:  
5BOJ - PubMed Abstract: 
The plasma protein transthyretin (TTR) is linked to human amyloidosis. Dissociation of its native tetrameric assembly is a rate-limiting step in the conversion from a native structure into a pathological amyloidogenic fold. Binding of small molecule ligands within the thyroxine binding site of TTR can stabilize the tetrameric integrity and is a potential therapeutic approach. However, through the characterization of nine different tetramer-stabilizing ligands we found that unspecific binding to plasma components might significantly compromise ligand efficacy. Surprisingly the binding strength between a particular ligand and TTR does not correlate well with its selectivity in plasma. However, through analysis of the thermodynamic signature using isothermal titration calorimetry we discovered a better correlation between selectivity and the enthalpic component of the interaction. This is of specific interest in the quest for more efficient TTR stabilizers, but a high selectivity is an almost universally desired feature within drug design and the finding might have wide-ranging implications for drug design.
Organizational Affiliation: 
Department of Medical Biochemistry and Biophysics, Umeå University , 901 87 Umeå, Sweden.