Structural and spectral analysis of 3-metoxytyramine, an important metabolite of dopamine

Abstract

Density functional theory calculations, with B3LYP functional and 6-311++G(d,p) basis set are performed with the aim to support the molecular structure and the spectroscopic characteristics of 3-methoxytyramine, the major extracellular metabolite of dopamine. Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) analysis were used to explain the specific interactions in the most stable conformations in vacuum and water. The conformer resembling the crystallographic structure was compared to the experimentally available data and NMR spectra. The detailed vibrational spectral analysis and the assignments of the bands, done on the best-fit basis comparison of the experimentally obtained and theoretically calculated IR and Raman spectra, match quite well indicating DFT calculations as very accurate source of normal mode assignments. The obtained results demonstrate the applicability and performance of DFT calculations in conformational analysis of 3-methoxytyramine at the state of the isolated molecule. The molecular docking showed that the most stable conformation in vacuum was not the most stable one when docked in protein, proving that only the weak interactions stabilize the gaseous phase conformations.