Paper Number
BA3 

Session
Biorheology & Active Fluids

Title
Using solution shear to test the effects of protein conformational flexibility on dense liquid protein clusters

Presentation Date and Time
February 13, 2017 (Monday) 10:50

Track / Room
Track 2 / Audubon A

Authors (Click on name to view author profile)

1. Byington, Michael C. (University of Houston)
2. Safari, Mohammad S. (University of Houston)
3. Conrad, Jacinta C. (University of Houston)
4. Vekilov, Peter G. (University of Houston)

Author and Affiliation Lines (in printed abstract book)
Michael C. Byington, Mohammad S. Safari, Jacinta C. Conrad, and Peter G. Vekilov
University of Houston, Houston, TX

Speaker / Presenter 
Conrad, Jacinta C.

Text of Abstract
Shear flow alters the rate at which crystals nucleate from solution, yet the underlying mechanisms remain poorly understood. Here, we explore the response to shear of dense liquid clusters, which may serve as crystal nucleation precursors. Solutions of the protein lysozyme were sheared in a Couette cell at rates from 0.3 to 200 s^-1 for up to seven hours. The cluster size and total population volume were characterized by dynamic light scattering. We demonstrate that shear rates greater than 10 s^-1 applied for longer than one hour reduce the volume of the cluster population. The likely mechanism of the observed response involves enhanced partial unfolding of the lysozyme molecules, which exposes hydrophobic surfaces between the constituent domains to the aqueous solution. We show that disruption of the intramolecular S-S bridges does not contribute to the mechanism of response to shear. The decrease of the cluster population with increasing shear rate or shear time suggests that nucleation may be inhibited at relatively high shear rates and that nucleation rate enhancement due to shear may be due to alternative mechanisms.