Exploring the Nature of Carbohydrate-Aromatic Dispersion Interactions via Sophisticated Computational Chemistry Tools
|Year of publication
|MU Faculty or unit
|There are several ways how saccharides interact with proteins. The role of dispersion-driven CH-pi interactions in protein-carbohydrate interactions has been underestimated for a long time. This type of interaction occurs between carbohydrate apolar faces and aromatic amino-acid residues. We introduce first systematic study of CH-pi interactions between selected carbohydrates and aromatic amino-acid models: benzene and naphtalene. 3D interaction energy (Eint) scan was performed to elucidate interaction energy maps for carbohydrate-benzene interaction. Resulting most stable complexes were reoptimized and their Eint were refined at highly-sophisticated level. To study possible degree of additivity, we used geometries of carbohydrate-benzene complexes to build-up monodentate (interaction with one CH-group) and bidentate (interaction with two CH-groups) carbohydrate-naphtalene complexes. Also these complexes underwent the optimization and energy refinement procedure as described. Results show Eint in carbohydrate-benzene complex up to -5,40 kcal/mol, which corresponds to medium-strong hydrogen bond. We localized most attractive regions where the Eint is highest – the strongest interaction is localized above and under CH-groups of carbohydrate. Additionally, benzene can recognize the specific hydrogens of carbohydrate in specific ideal distance (|(C)H-pi| distance around 2,3 A). The aromatic ring is coplanar with the carbohydrate cycle. Localization of the strongest interaction regions for carbohydrate-benzene complex lead us to idea about possible additivity of the CH-pi interaction. Therefore, Eint of bidentate carbohydrate-napthalene complexes were analyzed. The hypothesis of total additivity of the interaction was not confirmed. However, the Eint exhibits certain degree of additivity. The Eint of bidentate complex (ranging up to -8,20 kcal/mol) forms 2/3 of sum of Eint of monodentate ones and 4/5 of sum of Eint of carbohydrate-benzene complexes.