@article {296, title = {DFT Calculation of Nitrogen Chemical Shifts in the Active Site of Vitamin D Receptor}, journal = {Polish Journal of Chemistry}, volume = {Vol. 80, no 7}, year = {2006}, pages = {1171{\textendash}1183}, abstract = {The complexed vitamin D receptor (VDR) is responsible for calcium homeostasis. Tryptophan is of special importance for the receptor{\textquoteright}s functions, as it appears just once in the VDR sequence and occupies the center of the ligand binding pocket. DFT calculations of nitrogen chemical shifts for Trp-NHSC moiety, presented in thiswork for liganded and free receptor, agree with NMR studies on the VDR specifically labeled with [UL] 15N2 Trp. Our calculations confirm orientation of the C(7)=C(8) vitaminDbond under the tryptophan ring. We suggest that interactions with water molecules are responsible for observed deshielding of indole Trp-nitrogen in unliganded VDR.}, keywords = {DFT calculations of nitrogen chemical shifts, nuclear receptors, protein ligand interactions, vitamin D receptor}, author = {Wanda Sicinska} }