Exploration of conformations and quantum chemical investigation of l-tyrosine dimers, anions, cations and zwitterions: a DFT study

Abstract

Conformational analysis of tyrosine (YN) and its ionized counter parts cations (YC), anions (YA) and biologically relevant zwitterionic form (YZ) has been carried out. An exhaustive and systematic exploration of l-tyrosine dimer (YD) conformations resulted in about 59 distinct minima on the potential energy surface. The hydrogen bonds and a variety of non-covalent interactions such as OH–π, NH–π, CH–π, CH–O and π–π interactions stabilized the different forms of tyrosine and its dimers. Atoms in molecules analysis was performed to evaluate the nature and strength of the non-covalent interactions. Over all the NH–O, hydrogen bonds have showed higher stability than other non-covalent interactions in this study. The most stable dimers predominantly possess hydrogen bonding interactions, while the ones with aromatic side chain interactions are less stable. A delicate balance of non-covalent interactions governed the stability of different forms of tyrosine and its dimers.