An investigation of the density functional theory (DFT) was carried out to study the effects of the hydrogen bond (HB) interactions on H-2, N-14, and O-17 electric field gradient (EFG) tensors in the active site of human dehydroepiandrosterone sulphotransferase (SULT2A1/DHEA). Natural Bonding Orbital (NBO) analysis was also performed on this active site. The results revealed that the magnitude of the quadrupole coupling constant (QCC) change at each nucleus directly depends on its contribution amount to the HB interaction. (C) 2016 Published by Elsevier B.V.