Conformations and properties of the L‐tryptophyl‐containing peptides in solution, depending on the pH—Theoretical study vs. experiments

Abstract

The conformational preference and electronic properties of three L-tryptophyl-containing dipeptides, i.e., glycyl-L-tryptophane (H-Gly-Trp-OH), L-alanyl-L-tryptophane (H-Ala-Trp-OH), and L-methionyl-L-tryptophane (L-Met-Trp-OH) in solution depending on the pH of the media are studied both theoretically and experimentally. The effect of the protonation of the COO(-) and deprotonation of the NH3+ as well as the alkaline hydrolysis of the amide fragment in a strong basic media on the electronic spectra are discussed. Ab initio and density functional theory (DFT) methods as well as the time-dependent DFT (TD-DFT) method as a function of the basis set are performed with a view to obtain the geometry and electronic properties of all of the species as well as the intermediate, obtained in the alkaline hydrolysis mechanism.

Organic mandelates as promising materials with non-linear optical application

“…The data are summarized in Table 1. As with the calculation of the optical properties of small L-tryptophancontaining peptides or NLO materials based on barbiturate salts [19,20] the DFT approximation at B3LYP level of theory, yielded serious shortcomings. The so-called M06-class functional [16][17][18] was used to enforce some fundamental exact constraints yielding a good correlation between the theoretical and the experimental values.…”

Synthesis, spectroscopic and structural study of trans- and cis-(±)-3-phenyl-4-(pyrrolidine-1-carbonyl)-isochroman-1-ones

“…5). This phenomenon could be explained with the origin of these sub-maxima of the crystal field splitting effect [26][27][28][29][30]. The inplane vibrations of the aromatic skeletons of both conformers differ Fig.…”

“…Non-polarized solidstate IR-spectra were obtained by a KBr disk technique. The oriented samples were achieved as a suspension in a nematic liquid crystal (ZLI 1695, Merck) by method [26][27][28][29][30].…”

“…Visualization of the selected molecular vibrations and resulting transition moments; the frequencies are given in [cm −1 ].Scheme 4.Gaps of the HOMO and LUMO MOs, using the theoretically tool described in details[28][29][30].…”

Experimental and Theoretical Spectroscopic Study of 3-Aryl-2-Phenyl-3-Phenylaminopropanoic Acids

“…The electronic structure and the molecular geometry of compounds 1-4 are obtained using the quantum chemical DFT approach [20][21][22][23][24]. The effect of the substituents on the molecular geometry is investigated.…”