Characterization of the effect of chromium salts on tropocollagen molecules and molecular aggregates

• Published in: International journal of biological macromolecules 2023-07, Vol.242 (Pt 2), p.124835-124835, Article 124835
• Main Authors: Sergeeva, Irina A., Klinov, Dmitry V., Schäffer, Tilman E., Dubrovin, Evgeniy V.
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Chromium (III) salts; Collagen; Collagenolysis; Dynamic light scattering; Microscopy, Atomic Force - methods; Persistence length; Salts - pharmacology; Tropocollagen; Water
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.124835

Though the capability of chromium treatment to improve the stability and mechanical properties of collagen fibrils is well-known, the influence of different chromium salts on collagen molecules (tropocollagen) is not well characterized. In this study, the effect of Cr3+ treatment on the conformation and hydrodynamic properties of collagen was studied using atomic force microscopy (AFM) and dynamic light scattering (DLS). Statistical analysis of contours of adsorbed tropocollagen molecules using the two-dimensional worm-like chain model revealed a reduction of the persistence length (i.e., the increase of flexibility) from ≈72 nm in water to ≈56–57 nm in chromium (III) salt solutions. DLS studies demonstrated an increase of the hydrodynamic radius from ≈140 nm in water to ≈190 nm in chromium (III) salt solutions, which is associated with protein aggregation. The kinetics of collagen aggregation was shown to be ionic strength dependent. Collagen molecules treated with three different chromium (III) salts demonstrated similar properties such as flexibility, aggregation kinetics, and susceptibility to enzymatic cleavage. The observed effects are explained by a model that considers the formation of chromium-associated intra- and intermolecular crosslinks. The obtained results provide novel insights into the effect of chromium salts on the conformation and properties of tropocollagen molecules. •The effect of chromium (III) salts treatment on collagen molecules is studied.•An approach for AFM study of collagen molecules on graphitic surface is developed.•AFM reveals the increase of flexibility of chromium treated collagen molecules.•DLS demonstrates aggregation of collagen molecules in chromium salt solutions.•A model explaining the observed effects is proposed.