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Carbohydrate - Protein aromatic ring interactions beyond CH/π interactions: A Protein Data Bank survey and quantum chemical calculations

Ivana M. Stanković, Jelena P. Blagojević Filipović, S. Zarić

International Journal of Biological Macromolecules, 2020

16 citations

Abstract

The geometries of the contacts between monosaccharides and aromatic rings of amino acids found in X-ray crystallography structures, in the Protein Data Bank (PDB), were analyzed, while the energies of the interactions were calculated using quantum chemical method. We found 1913 sugar/aromatic ring contacts, 1054 of them (55%) with CH/π interactions and 859 of them (45%) without CH/π interactions. We showed that only the carbohydrate/aromatic contacts with CH/π interactions are preferentially parallel and enable sliding in the plane parallel to aromatic ring. The calculated interaction energies in systems with CH/π interactions are in the range from -1.7 kcal/mol to -6.8 kcal/mol, while in the systems without CH/π interactions are in the range -0.2 to -3.2 kcal/mol. Hence, the binding that does not include CH/π interactions, can also be important for aromatic amino acid and carbohydrate binding processes, since some of these interactions can be as strong as the CH/π interactions. At the same time, these interactions can be weak enough to enable releasing of small carbohydrate fragments after the enzymatic reaction. The analysis of the protein-substrate patterns showed that every second or third carbohydrate unit in long substrates stacks with protein aromatic amino acids.

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