The concentration-dependence of the diffusion and sedimentation coefficients ( kDand ks, respectively) of a protein can be used to determine the second virial coefficient (B2), a parameter valuable in predicting protein-protein interactions. Accurate measurement of B2 under physiologically and pharmaceutically relevant conditions, however, requires independent measurement of kDand ks via orthogonal techniques. We demonstrate this by utilizing sedimentation velocity (SV) and dynamic light scattering (DLS) to analyze solutions of hen-egg white lysozyme (HEWL) and a monoclonal antibody (mAb1) in different salt solutions. The accuracy of the SV-DLS method was established by comparing measured and literature B2 values for HEWL. In contrast to the assumptions necessary for determining kDand ks via SV alone, k Dand ks were of comparable magnitudes, and solution conditions were noted for both HEWL and mAb1 under which 1), kDand ks assumed opposite signs; and 2), kD ≥ ks. Further, we demonstrate the utility of kDand ks as qualitative predictors of protein aggregation through agitation and accelerated stability studies. Aggregation of mAb1 correlated well with B2, kD, and ks, thus establishing the potential for k D to serve as a high-throughput predictor of protein aggregation. © 2010 by the Biophysical Society.
Saluja, A., Fesinmeyer, R. M., Hogan, S., Brems, D. N., & Gokarn, Y. R. (2010). Diffusion and sedimentation interaction parameters for measuring the second virial coefficient and their utility as predictors of protein aggregation. Biophysical Journal, 99(8), 2657–2665. https://doi.org/10.1016/j.bpj.2010.08.020