Rapid quantitative characterization of protein interactions by composition gradient static light scattering

Abstract

Two new applications of the recently developed technique of composition gradient static light scattering (CGSLS) are presented. 1), The method is demonstrated to be capable of detecting and quantitatively characterizing reversible association of chymotrypsin and bovine pancreatic trypsin inhibitor in a solution mixture and simultaneously occurring reversible self-association of chymotrypsin at low pH in the same mixture. The values of equilibrium constants for both self- and hetero-association may be determined with reasonable precision from the analysis of data obtained from a single experiment requiring <15 min and <1 mg of each protein. 2), Analysis of the results of a single CG-SLS experiment carried out on Ftsz, a protein that self-associates to form linear oligomers of indefinite size in the presence of guanosine diphosphate, yields the dependence of the equilibrium constant for monomer addition upon oligomer size. © 2006 by the Biophysical Society.