Mechanical response of polyprotein revealed by single-molecule optical tweezers

We researched the mechanical unfolding of protein domains in monomeric protein NuG2 and the tandem polyproteins (NuG2)(8) and (NuG2)(16) using a dual-trap optical tweezers system. By stretching NuG2 and its polyproteins, (NuG2)(8) and (NuG2)(16) at the constant pulling speed of 500 nm s(-1), we achieved the mechanical unfolding force of each domain in these proteins. Besides, we calculated the energy dissipation of NuG2, (NuG2)(8) and (NuG2)(16) by measuring the area enclosed by stretching and relaxation traces. Our results represent a key step towards engineering artificial polyproteins with controllable mechanical force and energy dissipation properties for force-buffering and energy dissipator applications.