Bovine serum albumin unfolds in Couette flow

Abstract

Direct measurements of the effect of hydrodynamic forces generated in Couette flow on the secondary and tertiary structure of bovine serum albumin (BSA) are reported. Real time measurements were made using both fluorescence and circular dichroism spectroscopy as complementary measures of protein structure. Our results demonstrate that BSA, a medium sized, predominantly α-helical protein, unfolds irreversibly in simple shear flow. The shear rates used in this study are comparable to those encountered in bioprocessing and in physiology. Flow-induced unfolding of BSA occurs in simple Couette flow where both exposure time and shear rate increase the degree of irreversible unfolding.