I have studied several protein-protein interactions and often binding will result in very large proton shifts, I know alot of people will blame this on packing against or proximity to an aromatic ring or something of that nature, recently ive come across a few paticularly large shifts say 1.5-2 ppm and its been sugested these are too big for aromatic shifts and must be from the formation of a hydrogen bond.
does anyone know any good papers/ databases where the max shift you can expect from aromatic effects have been examined?
