Probing Mechanical Properties of Collagen at the Molecular Level

INTRODUCTION In the past decade, the field of single-molecule mechanics has grown rapidly, and through the use of techniques such as atomic-force microscopy (AFM) and optical tweezers, much has been learned about the molecular mechanisms responsible for mechanical response [1]. In spite of this, there have been few studies relating mechanical response across a range of hierarchies, in order to relate molecular-level mechanics to mechanics at higher levels of structure. We are taking a systematic approach to this problem, by developing optical tweezers instruments capable of probing protein mechanics at various levels of assembly, and by focussing our studies on collagen, for which we have developed a recombinant expression system. Collagen undergoes hierarchical assembly, from isolated triple-helical molecules to fibrils to higher-order structures found in connective tissues, allowing us to isolate and probe mechanics at different levels of structural assembly.