Issue 4, 2020

Enhancing the enthalpic contribution of hydrogen bonds by solvent shielding

Abstract

In biological systems, polar interactions are heavily burdened by high desolvation penalties resulting from strong solute–solvent interactions. As a consequence thereof, enthalpic contributions of hydrogen bonds to the free energy of binding are severely diminished. However, this effect is strongly attenuated for interactions within solvent-shielded areas of proteins. In microcalorimetric experiments, we show that the bacterial lectin FimH utilizes conformational adaptions to effectively shield its binding site from solvent. The transition into a lower dielectric environment results in an enthalpic benefit of approximately −13 kJ mol−1 for mannoside binding. However, this effect can be abrogated, if the hydrogen bond network within the binding site is disturbed by deoxygenation of the ligand. Conformational adaption leading to reduced local dielectric constants could represent a general mechanism for proteins to enable enthalpy-driven recognition of polar ligands.

Graphical abstract: Enhancing the enthalpic contribution of hydrogen bonds by solvent shielding

Supplementary files

Article information

Article type
Paper
Submitted
26 jun 2020
Accepted
19 avg 2020
First published
28 avg 2020
This article is Open Access
Creative Commons BY-NC license

RSC Chem. Biol., 2020,1, 281-287

Enhancing the enthalpic contribution of hydrogen bonds by solvent shielding

J. Cramer, X. Jiang, W. Schönemann, M. Silbermann, P. Zihlmann, S. Siegrist, B. Fiege, R. P. Jakob, S. Rabbani, T. Maier and B. Ernst, RSC Chem. Biol., 2020, 1, 281 DOI: 10.1039/D0CB00108B

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