The collagens are a family of more than 20 different proteins, all sharing the same basic structure. Collagen is the most abundant protein in mammals, comprising more than a quarter of the total protein in the human body. Its main role is in connective tissues, such as bone, cartilage, tendons and skin, where it is a vital structural element providing support and rigidity. Even small mutations can lead to weakened tissues, and genetic diseases such as brittle bone syndrome and osteoarthritis. Understanding the mechanical properties of collagen at the molecular level is important for understanding its role in these tissues, their formation, and their degeneration. In humans it has been found that the melting temperature of collagen – the temperature at which the molecule unwinds and separates – is very close to body temperature. The melting temperatures of various types of collagen have been found to be closely linked to the body temperature of the species in which they are present. This indicates that the thermal stability of collagen may be of great relevance to the structural role it plays. Benjamin Downing is investigating how temperature affects the collagen molecule’s strength and flexibility. He is using optical tweezers – a device that employs a tightly focused laser beam to manipulate micron-sized objects – to stretch the molecule and measure its stiffness and elasticity over a range of temperatures. This will reveal how closely the mechanical and thermal stabilities of the molecule are correlated. Downing’s research will help shed light on how the structure of a molecule gives it a particular strength and flexibility, knowledge that may be useful in the future design of artificial molecules that have specific properties. This information could be relevant in the development of biomaterials with applications in tissue repair.