Revisiting the conformational transition model for the pH dependence of BSA structure using photoluminescence, circular dichroism, and ellipsometric Raman spectroscopy

Changes in pH affect metabolic pathways, primarily by modulating enzyme conformations, which is why a detailed analysis of pH -driven conformational transitions is required to understand the underlying biochemistry of diseases and biological organisms. In this work, we examined the pH -driven conformational dynamics of Bovine Serum Albumin (BSA), within the framework of the Foster Model. Circular Dichroism and Raman Optical Activity showed the conversion of helical into beta-rich structures in the acid and basic regions, while an opening of BSA tertiary structure was shown by the upsurging of accessibility of ANS-BSA binding sites and the increasing of random contributions at regions F and B. We could then revisit the Foster Model by introducing two additional intermediate conformational states and structural reorganization at extreme pH values. This expanded model opens up new possibilities concerning protein-molecule interactions, promising far-reaching implications for fields such as drug design and biomaterials.