Effect of pH on the conformation of bovine serume albumin - gold bioconjugates

• Published in: Journal of molecular liquids 2020-07, Vol.309, p.113065, Article 113065
• Main Authors: Fehér, Bence, Lyngsø, Jeppe, Bartók, Boróka, Mihály, Judith, Varga, Zoltán, Mészáros, Róbert, Pedersen, Jan Skov, Bóta, Attila, Varga, Imre
• Format: Article
• Language: English
• Subjects: BSA; Gold; Reversibility; SAXS
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2020.113065

Biodegradable, biocompatible nanoparticles with tuneable fluorescence - due to their great potential in biology, medicine and sensor development - are widely studied nowadays. Recently it was shown that the complex red emitting spectroscopic feature of Bovine Serum Albumin - gold (BSAAu) bioconjugates can be related to the versatility of conformational changes of the BSA protein. In our study, we performed a comprehensive study on the structural changes of the host BSA molecules by infrared spectroscopy (FTIR) and small-angle X-ray scattering (SAXS). Both methods revealed that the BSA structure is not reversible after a neutral - alkali - neutral pH cycle and this behaviour is more pronounced in the presence of the gold salt (HAuCl4). The changes in the monitored secondary structural elements of BSA-(HAuCl4) system, with the fitted molecular shapes indicate that all steps in the synthesis route influence both the fine and the global structures of BSA and result in a complex structural prehistory dependent hindering of the total structural reversibility. A robust connection exists between the structural/conformational changes and the fluorescence behaviours. •Monitoring the structure of BSA and BSA – gold conjugates during a pH cycle•Reconstruction of molecular shapes by the means of small-angle X-ray scattering•The effect of gold on the atomic structure and the shape of conjugates•Monitoring the fluorescence behaviours and their relation to structural features