Effective interactions in protein solutions with and without clustering

Fajun Zhang, Michal K. Feustel, Maximilian W.A. Skoda, Robert M.J. Jacobs, Felix Roosen-Runge, Tilo Seydel, Michael Sztucki and Frank Schreiber

Physica A: Statistical Mechanics and its Applications, 2024, vol. 650, issue C

Abstract: Protein interactions in solution and the question of cluster formation are of paramount importance to a wide range of research fields and industrial applications. Protein clustering can arise due to a delicate interplay between the short-range attraction and the long-range repulsion in the interaction potential. This study employs small angle X-ray scattering (SAXS) to examine the clustering behavior of three protein systems in solution: bovine serum albumin (BSA), bovine β-lactoglobulin (BLG) and lysozyme (LYZ) under varying protein concentrations, ionic strengths and temperatures. The goal is to elucidate the influence of the attractive potential’s nature on clustering behavior. BSA serves as a reference system, where electrostatic repulsions dominate the effective interactions, resulting in a mean protein–protein distance as a function of protein concentration which follows the 1/3 power law and precludes protein cluster formation. In contrast, BLG and LYZ solutions exhibit exponents less than 1/3, indicating concentration-dependent cluster formation. The effective interactions are well described using a two-Yukawa type potential comprising a long-ranged repulsion and a short-ranged attraction. While increasing ionic strength by adding NaCl reduced repulsion and correlation in all three systems, the response of protein solutions to ionic strength differed for clustering systems of BLG and LYZ. BLG solutions exhibited a reduced attraction with increasing ionic strength, leading to cluster dissolution, while LYZ solutions experienced enhanced attraction, favoring larger cluster formation. Notably, BLG solutions showed minimal temperature dependence, while LYZ solutions exhibited increased attraction with decreasing temperature, further promoting cluster formation. These results demonstrate the crucial role of short-ranged attractions of specific nature in determining protein clustering behavior. A thorough understanding of protein interactions is essential for predicting protein clustering and phase behavior.

Keywords: Protein interaction; Protein clustering; Competing interactions; SAXS; BSA; BLG; Lysozyme (search for similar items in EconPapers)
Date: 2024
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Persistent link: https://EconPapers.repec.org/RePEc:eee:phsmap:v:650:y:2024:i:c:s0378437124005041

DOI: 10.1016/j.physa.2024.129995

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