Studying the Interaction between L-Methionine and Picolinic and Nicotinic Acids by Means of Densimetry and Quantum Chemistry

• Published in: Russian Journal of Physical Chemistry A 2022, Vol.96 (1), p.99-108
• Main Authors: Tyunina, E. Yu, Tarasova, G. N., Dunaeva, V. V.
• Format: Article
• Language: English
• Subjects: Amino acids; Buffer solutions; Buffers (chemistry); Chemistry; Chemistry and Materials Science; Density functional theory; Dilution; Isomers; Methionine; Molar volume; Physical Chemistry; Physical Chemistry of Solutions; Quantum chemistry
• ISSN: 0036-0244; 1531-863X
• DOI: 10.1134/S0036024422010253

Densimetry and computer modeling are used to study the interaction between L-methionine (Met) and picolinic (PA) and nicotinic (NA) acids in an aqueous buffer solution (pH 7.4). The first experimental densities are obtained for Met–buffer, PA–buffer, and Met–PA–buffer systems at T = 288.15, 298.15, 303.15, 308.15, and 313.15 K. Results include the apparent molar volumes ( V φ ) of pyridinecarboxylic acid isomers and their limiting apparent molar volumes ( ) at infinite dilution in solutions containing an amino acid (with a concentration of 0.0125 mol kg −1 ). The extreme concentration relations of the apparent molar volumes indicate the structural strengthening effect PA and NA have on solutions containing an amino acid (Met), and the maxima shift slightly upon an increase in temperature. Derivatives ( ) p and ( ) p are calculated, along with partial molar volumes of the transfer of isomers from a buffer to buffer solutions of an amino acid. Results are discussed in the context of the Gurney model. Met complexes with PA and NA are modeled by means of quantum chemistry at the B3LYP level of density functional theory using the Gaussian_03 software in combination with the correlation-consistent cc-pVTZ basis set.