Publication details

Water-tryptophan interactions: lone-pair-pi or O-H-pi? Molecular dynamics simulations of beta-galactosidase suggest that both modes can co-exist



Year of publication 2018
Type Article in Periodical
Magazine / Source Chemistry - A European Journal
MU Faculty or unit

Faculty of Science

Web DOI: 10.1002/chem.201705364
Field Physical chemistry and theoretical chemistry
Keywords water; tryptophane; interaction; molecular dynamics
Attached files
Description In proteins, the indole side-chain of tryptophan can interact with water molecules either in-plane, forming H-bonds, or out-of-plane, with the water molecule contacting the aromatic pi-face. The latter interaction can be either of the lone-pair---pi (lp---pi) type or correspond to the O-H---pi binding mode, an ambiguity that X-ray structures usually do not resolve. Here we report molecular dynamics (MD) simulations of a solvated beta-galactosidase monomer which illustrate how a water molecule located at the pi-face of an indole side-chain of tryptophan can adapt to the position of proximate residues and "select" its binding mode. In one such site, the water molecule is predicted to rapidly oscillate between the O-H---pi and lp---pi binding modes, gaining thus entropic advantage. Our MD simulations provide support for the role of lp---pi interactions in the stabilization of protein structures.
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