Study of Large Multimeric Biomolecules by Single-Molecule Manipulation and Imaging

Single-molecule manipulation enables us to study the properties of long chain, multimeric biomolecules. Perlecan, a giant secreted heparin sulfate proteoglycan, is a major component of basement membrane, bone stroma and blood vessels. It is involved in processes such as cell adhesion, migration and modulation of apoptosis. The changes in its synthesis and function are closely associated with many diseases, including cancer. Von Willebrand factor is a large multimeric protein circulating in blood, and is crucial for initiation of blood coagulation. We use atomic force microscope to obtain force curves and images of these proteins. We characterized the mechanical property of perlecan as well as the domain conformational changes of von Willebrand factor. The results demonstrate that single-molecule manipulation can probe directly the dynamics of large biomolecules that are usually not accessible with other methods.