Titin Domain Unfolding: AFM Force Spectroscopy

This simulator models a single molecule of titin — the giant elastic protein of the muscle sarcomere — as it is stretched by a virtual atomic-force-microscope cantilever, exactly as in the single-molecule pulling experiments that first revealed how titin generates passive muscle tension. A chain of folded immunoglobulin (Ig) domains is pulled at a controllable speed; force builds along a worm-like-chain curve until one domain's force-dependent unfolding rate (Bell's model) makes it snap open, adding ~25 nm of new contour length and dropping the force before the cycle repeats — producing the classic sawtooth force-extension trace plotted live alongside the 3D chain.