Self-entanglement of bovine serum albumin in shear flow: cumulative effects and irreversibility

We perform Brownian dynamics simulations of shear-induced unfolding of bovine serum albumin. This protein was reported to unfold irreversibly in the shear flow. Using a coarse-grained model of a protein, we track the conformational changes induced by the flow and observe that after an extended exposure to shear albumin loses its ability to refold even when the flow has been turned off. Instead, it is trapped in a metastable state characterized by a large degree of self-entanglement which prevents the molecule from folding into the native conformation. This state becomes more populated with time, which can explain the cumulative effect of the shear observed in the experiments.