(578e) Diffusing Colloid Measurements of Protein-Carbohydrate Interactions

Specific protein-carbohydrate interactions are critical to numerous processes in biology, medicine, and nanobiotechnologies. As a result, there is great interest in better understanding how to directly measure weak, short-range, and orientation specific protein-carbohydrate interactions on appropriate time, length, and energy scales. In this talk, we present measurements of non-specific and specific interactions between colloids and surfaces with and without conjugated proteins and carbohydrates. Interactions are obtained by novel measurements that analyze evanescent wave scattering and video microscopy measurements of 3D trajectories of colloids above planar surfaces. As a baseline for interpreting specific interactions, results will be presented for non-specific polymer-protein, polymer-carbohydrate, protein-protein, and carbohydrate-carbohydrate interactions. Specific interactions will be presented for colloids conjugated with proteins and several immobilized carbohydrates with different known dissociation constants. Ongoing work is investigating such protein-carbohydrate interactions in the presence of competitive binding with small saccharide ligands. Results show excellent agreement between experiment, theory and Brownian dynamics simulations.