Conformational changes of l-phenylalanine – Near infrared-induced mechanism of dimerization: B3LYP studies

Effect of metal Ions (Ni2+, Cu2+ and Zn2+) and water coordination on the structure of L-phenylalanine, L-tyrosine, L-tryptophan and their zwitterionic forms

“…However, in aqueous solution the zwitterions are the predominant species [2–4]. The zwitterionic form of amino acids ( + H 3 N–CH(R)–COO – ) can be stabilized by the presence of counter ions and/or water molecules [1, 3].…”

Molecular structure, vibrational spectra, NBO, UV and first order hyperpolarizability, analysis of 4-Chloro-dl-phenylalanine by density functional theory

“…The amino nitrogen of the phenylalanine residue forms an O─H…..N hydrogen bond with O atom through H of the carboxyl group. S. Olsztynska-Janus et al[50] clearly explained conformational structures of phenylalanine monomers, their energies and dipole moments in the gas phase and they were given Geometries of the seven lowest energy conformers of phenylalanine, optimized by Gaussian 03 package at the B3LYP/6-31G* level.The structure of our molecule 4CLPA is coinciding with conformer1 (exception of para chloro substitution) of the phenylalanine given by S. Olsztynska-Janus et al as shown in Supplementary material S2. The title structure is stabilized by an intramolecular hydrogen bond linking the carboxylic group to the amino group and by hydrogen bonded interaction between the amino hydrogen atoms and the π-electron system of the aromatic ring.…”

Specific Applications of Vibrational Spectroscopy in Biomedical Engineering

“…Most probably, properties of the water comprising a shell around DNA are modified during the irradiation in a manner dependent on the dose of NIR light exposure. According to results already obtained, the NIR-reshaped hydration shell leads to liposomes being more able to agglomerate (Komorowska et al, 2006) and to aggregation of L-phenylalanine (Olsztynska-Janus et al, 2009). The aim of the present research is an analysis of the phenomenon for DNA with limited water content.…”

“…In order to explain the process undergone following exposure to NIR, a simple object was studied, in this case phenylalanine amino acid (Olsztynska-Janus et al, 2009;OlsztynskaJanus et al, 2008). The FTIR-ATR spectra of L-phenylalanine aqueous solutions were measured between 4000 and 700 cm -1 .…”