A polarisable QM/MM description of NMR chemical shifts of a photoreceptor protein

ABSTRACT

We present a polarisable QM/MM investigation of NMR chemical shifts of a photoreceptor protein belonging to the Blue Light-Using Flavin family. Two different structures have been proposed for this photoreceptor which show a large variability in terms of the position and orientation of the protein residues around the flavin chromophore. Here, the two structures have been investigated with our multiscale approach using both DFT and MP2 level of theory. The picture that comes out comparing the ${}^1$H chemical shifts of the flavin and the most strongly interacting protein residues with the available experimental data, indicates a different behaviour of the two structures, with one showing a better correlation with NMR measurements. This shows that hybrid quantum chemical-classical simulations of NMR chemical shifts can indeed become a valuable tool to investigate the structure of complex biosystems.

GRAPHICAL ABSTRACT

KEYWORDS:

• QM/MM
• polarisable embedding
• NMR chemical shifts
• photoreceptor

Acknowledgments

The authors would like to thank Jurgen Gauss not only for his many seminal contributions to theoretical chemistry, including the ones that made this work possible, but also for the many moments spent together at conferences and during his visits to the group in Pisa.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors acknowledge funding from the European Research Council under the grant ERC-AdG-786714 (LIFETimeS).