DNA naturally twists until it may coil about itself. This twisting, called supercoiling, is caused by enzymes that travel along DNA’s helical groove resulting in forces and torques. As an example, such torque generated by the protein, E. coli RNA polymerase (RNAP) is found to be 10 piconewton-nanometers. A nanofabricated quartz cylinder was fabricated especially for this application.
||Proteins and peptides
Proteins and peptites arrange into complex isomeric structures. Determining the isomer beyond the molecule type is essential and may be life threatening. In one example, cow disease is caused by the mis-folded version of an otherwise harmless prion protein. In conjunction with AFM, tip-enhanced Raman spectroscopy (TERS) can be used to scan across a single molecule and provide an insightful bonds representation beyond the diffraction limit of visible light.