In Silico Analysis of Serum Albumin Binding by Bone-Regenerative Hyaluronan-Based Molecules.

Background: The binding of glycosaminoglycans (GAG) to Wnt signaling components plays a key regulatory role in bone formation and regeneration. We previously reported de novo designed chemically modified hyaluronan derivatives, named REGAG (Rationally Engineered GAG), which demonstrated bone-regenerative properties in a mouse calvaria defect model. To gain initial insights into the pharmacological profile of two REGAG currently under preclinical investigation in mice, we performed a comprehensive in silico investigation of their binding to human and murine serum albumin (HSA and MSA), as it might influence their ADME properties. Furthermore, we evaluated whether REGAG binding might impact the recognition of well-characterized HSA-binding drugs. Methods: State-of-the-art in silico ADMET tools, docking and molecular dynamics simulations were used to predict and characterize the interaction of REGAG with HSA and MSA, and to investigate the molecular mechanisms involved at the atomic level. Results: The investigated REGAG molecules show a consistent binding preference for the FA1 site in both proteins, and an additional preference for the FA7 site in HSA. Their recognition might induce protein conformational changes and alter the functional state. Furthermore, REGAG's conformational adaptability is predicted to influence their binding to the FA5/6 and FA8/9 sites of HSA, and to the FA3/4 and FA7 sites of MSA. Conclusions: Our investigations predict the binding of two hyaluronan derivatives to HSA and MSA. The mechanistic insights gained into the molecular recognition of these two REGAG molecules offer valuable information for their potential clinical application and serve as a rational basis for future molecular design aimed at improving pharmacokinetic properties.