Water-tryptophan interactions: lone-pair-pi or O-H-pi? Molecular dynamics simulations of beta-galactosidase suggest that both modes can co-exist
| Authors | |
|---|---|
| Year of publication | 2018 |
| Type | Article in Periodical |
| Magazine / Source | Chemistry - A European Journal |
| MU Faculty or unit | |
| Citation | |
| web | DOI: 10.1002/chem.201705364 |
| Doi | https://doi.org/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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