Coiled coils as mechanical building blocks The natural abundance of Coiled Coil (CC) motifs in cytoskeleton and extracellular matrix proteins suggests that CCs play an important role as passive (structural) and active (regulatory) mechanical building blocks. CCs are self assembled superhelical structures consisting of 2 7 α helices. Self assembly is driven by hydrophobic and ionic interactions while the helix propensity of the individual helices contributes additional stability to the structure. As a direct result of this simple sequence structure relationship CCs serve as templates for protein design and sequences with a pre defined thermodynamic stability have been synthesized de novo. Despite this quickly increasing knowledge and the vast number of possible CC applications the mechanical function of CCs has been largely overlooked and little is known about how different CC design parameters determine the mechanical stability of CCs. Once available this knowledge will open up new applications for CCs as nanomechanical building blocks e.g. in biomaterials and ...