ABSTRACT
The aim of this work is to evaluate the vibrational and structural properties of l-cysteine ethyl ester hydrochloride (CE), and its electronic behavior mainly in relation to the action of the thiol and amine groups at different degrees of solvation. The crystal structure of CE was determined at room temperature by X-ray diffraction methods. Infrared and Raman spectra were collected to compare the behavior of different functional groups in the molecule, both in the solid phase and in aqueous solution. Its UV and circular dichroism spectra were also measured in aqueous solution. The influence of an aqueous environment on the CE spectra was simulated by means of implicit (polarizable continuum model) and explicit (molecular dynamics, solute-solvent clusters) methods. Calculations in explicit and continuous solvent are of interest to explain the behavior of bioavailable sites in this medium. The study was completed by natural bond orbital analysis to determine the presence of hyperconjugative interactions.
Subject(s)
Cysteine/analogs & derivatives , Water/chemistry , Circular Dichroism , Crystallography, X-Ray , Cysteine/chemistry , Hydrogen Bonding , Molecular Conformation , Molecular Dynamics Simulation , Solutions , Solvents , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Thermodynamics , VibrationABSTRACT
Conformational and structural features of phenethylamine and phenylimidazoline derivatives with alpha-adrenergic activity have been studied by MNDO and PCILO methods. From the calculated conformational energy maps, we conclude that phenethylamines exhibit an extended conformation, while the phenylimidazolines adopt a position intermediate between that of corresponding extended and folded conformations. We conclude that the phenethylamines interact with classical Easson-Stedman sites, while the phenylimidazolines interact with a different site. Both phenethylamines and phenylimidazolines show similar requirements for a cationic recognition site.
