Biological macromolecules such as proteins are remarkable machines at the nano scale. The mechanical motion of proteins that is present in every living system allows those molecules to perform theie specific tasks. Most proteins are enzymes. Enzymes bind to their substrates, speed up the chemical reaction and release the products. Upon this binding and unbinding they undergo a large conformational motion. In case of Guanylate Kinase, the protein under study in my thesis, this deformation is about 1 nm, relatively large compared to the enzyme’s size (∼ 4nm). This conformational motion is essential to the protein’s activity. Proteins are not rigid solids, but rather deformable, wiggling and jiggling inside a medium. This deformability is a general materials property of a folded protein. Enzymes can be deformed and their activity can be modulated by perturbations other than ligand binding.