The effect of shear stress on bovine lactoferrin

Bovine lactoferrin is a multi-functional glycoprotein susceptible to environmental changes which can alter its structure and functionality. This paper explores the impact of shear stress on this protein in the presence of an air interface. Lactoferrin remained stable in 10 mM buffer when sheared at 4000 s −1 for 1h, while aggregate size increased from 13 to 405 nm in de-ionized water. The thermal stability of this latter sample also declined, with solution turbidity increasing after heating for 10 min at 80 o C. This increased protein association could be related to higher surface hydrophobicity in de-ionized water. The iron-binding capacity of lactoferrin did not vary with shear stress but was notably higher in de-ionized water at pH 5.5 and buffer at pH 7. The study also compared UV absorbance, the Bradford Assay, and an Index of Refraction sensor for measuring protein concentration in turbid solutions, with the sensor proving the most effective.