4: Biophysical and functional characterization of bovine lactoferrin as an antibacterial compound

Abstract: Lactoferrin (LF) is an iron-binding glycoprotein and is one of the most abundant antibacterial proteins that is commonly found in milk and most biological fluids. This antimicrobial property makes this protein appealing for pharmaceutical applications. Since protein function is linked to its biophysical properties, we are investigating the behavior of LF in various conditions, focusing on variables like temperature, ionic effects, and storage conditions. Thermal transitions were characterized using calorimetry, structural changes were monitored by circular dichroism (CD) spectroscopy, and aggregation behavior was assessed by dynamic light scattering (DLS). Native LF exhibits a compact globular structure with a hydrodynamic diameter of approximately 8-10 nm. Upon heating, a transition near the denaturation temperature is accompanied by changes in secondary structure and a pronounced increase in particle size, indicating aggregation. These aggregates persist after cooling. The presence of different ionic conditions modulates aggregation behavior, affecting both size distribution and dispersity. In addition, repeated freeze–thaw cycles induce measurable changes in particle size and secondary structure. Considering the impact of such biophysical properties on the functional activity of LF is crucial in ensuring optimal performance in various pharmaceutical applications.