Mechanics and structural stability of the collagen triple helix

The primary building block of the body is collagen, which is found in the extracellular matrix and in many stress-bearing tissues such as tendon and cartilage. It provides elasticity and support to cells and tissues while influencing biological pathways including cell signaling, motility, and differentiation. Collagen's unique triple helical structure is thought to impart mechanical stability. However, detailed experimental studies on its molecular mechanics have been only recently emerging. Here, we review the treatment of the triple helix as a homogeneous flexible rod, including bend (standard worm-like chain model), twist, and stretch deformations, and the assumption of backbone linearity. Additionally, we discuss protein-specific properties of the triple helix including sequence dependence, and relate single-molecule mechanics to collagen's physiological context.