Direct force measurements of the streptavidin-biotin interaction

The interaction between streptavidin and its ligand, biotin, were studied b y direct force measurements. The complimentary approaches of surface force apparatus (SFA) and atomic force microscopy (AFM) were used to elucidate bo th long-range and short-range adhesive interactions of the streptavidin-bio tin interaction. The high spatial resolution of the SFA provided a detailed profile of the intersurface forces of apposing surfaces functionalized wit h streptavidin and biotin. Measurements obtained by the SFA corresponded to long and intermediate-range forces that are important in determining ligan d-receptor association. AFM was used to measure the unbinding force of indi vidual streptavidin-biotin complexes. These measurements revealed the short -range interactions (i.e. hydrophobic and hydrogen bonding forces) that sta bilize the intermolecular bond. (C) 1999 Elsevier Science B.V. All rights r eserved.