DYNAMICS OF BIOMOLECULES AND CELLS 2014Unfolding of the elastomeric protein titin using atomic force microscopyWhy atomic force microscopy is best suited for this taskA trial on the role that atomic force microscopy plays in titin unfolding and why atomic force microscopy is suitable for such experiments Proteins are a group of molecules, found in the human body (and in other living organisms ), which have varied functions. They are made up of chains of smaller molecules called amino acids. Amino acids are arranged in long chains, these chains are then folded to form a functional component. Proteins have many different functions, such as bioregulation (in the case of hormones). There are transport proteins which, for example, move minerals in the body, structural proteins make up the skin, bones and certain proteins are catalytic (enzymes). This essay focuses on an elastomeric protein. An elastomer is an elastic polymer; Elastomeric proteins are multi-unit proteins that exhibit elasticity. Elasticity is the ability of a solid material to return to its original shape after deformation. The physical origin of elasticity varies depending on the material. In the case of rubber and other elastic polymers, elasticity results from the stretching of the polymer chain (when a force is applied to it) of which the elastic polymer is made. To study the elasticity of proteins, one must use a tool that can measure the force required to achieve a certain extension of the polymer. One such tool is the atomic force microscope (AFM). An AFM uses a sharp tip on an overhang that deflects when brought closer to a surface. The deflection of the cantilever can be measured and the topography of the sample...... middle of article......i, Z. & Kellermayer, M. Individual globular domains and deployment of Domains visualized in overstretched titin molecules with atomic force microscopy. PLoS One 9, e85847 (2014).15. Puchner, EM et al. Mechanoenzymes of titin kinase. Proc. Natl. Acad. Sci. United States 105, 13385-90 (2008).16. Kellermayer, MS & Granzier, HL Elastic properties of single titin molecules made visible through fluorescent binding of F-actin. Biochemistry. Biophysics. Res. Common. 221, 491–7 (1996).17. Neuman, KC & Nagy, A. Single-molecule force spectroscopy: optical tweezers, magnetic tweezers, and atomic force microscopy. Nat. Methods 5, 491-505 (2008).18. Jannasch, A., Demirörs, A.F., van Oostrum, PDJ, van Blaaderen, A. & Schäffer, E. Nanonewton optical force trap using antireflective coated, high refractive index titanium microspheres. Nat. Photonics 6, 469–473 (2012).