The application of Kirkwood-Buff theory to study hydration properties of $\alpha$-amino acids

Štefanič, Zala (author), Hribar-Lee, Barbara (author)

Protein conformational stability and function depend on non-covalent interactions that are strongly influenced by the surrounding environment. To explore protein properties, amino acids are often utilized as model systems. In this study, we determined the densities of seven α-amino acids in aqueous solutions between 278.15 K and 308.15 K and calculated the apparent molar volumes. Linear extrapolation yielded standard molar volumes, which were analyzed to characterize amino-acid hydration. The contributions of side chains to the standard molar volume were determined relative to glycine. The standard molar volume increased with temperature, indicating reduced electrostriction of water around the amino acids, consistent with lower hydration numbers at higher temperatures. We employed the Ornstein-Zernike integral equation with hypernetted-chain closure and a coarse-grained Lennard-Jones bead model to calculate pair correlation functions and Kirkwood-Buff integrals, from which standard molar volumes were obtain. The model reproduced the experimental standard molar volumes very well.

• Language: English
• Keywords: amino acids, apparent molar volume, standard molar volume, hydration number, integral equation, Kirkwood-Buff theory
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 11 str.
• Numbering: Vol. 29, iss. 1, art. 13801
• PID: 20.500.12556/RUL-181390
• UDC: 577.322
• ISSN on article: 1607-324X
• DOI: 10.5488/CMP.29.13801
• COBISS.SI-ID: 274187779
• Publication date in RUL: 03.04.2026

Record is a part of a journal

• Title: Condensed matter physics
• Shortened title: Condens. matter phys.
• Publisher: Institute for Condensed Matter Physics.
• ISSN: 1607-324X
• COBISS.SI-ID: 33562117

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Ukrainian
• Keywords: aminokisline, navidezni molski volumen, standardni molski volumen, hidratacijsko število, integralna enačba, Kirkwood-Buffova teorija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0201
• Name: Fizikalna kemija

• Funder: ARIS - Slovenian Research and Innovation Agency
• Funding programme: Young researchers