Orientation and transformation of flagella in electrostatic field

As an extension of electrostatic molecular manipulation being developed by the authors using a high-frequency high-intensity field produced in microfabricated electrode systems, electrically induced transformation of bacterial flagella is studied. Flagella are known to assume a variety of distinct helical forms, and transformations among these polymorphic states are induced by environmental changes or by mechanical force. The orientation time constant of flagella is measured under the electrostatic field produced in microfabricated electrodes in order to estimate the magnitude of the induced dipole moment. Then, the field intensity is further raised in order to observe the electrostatically induced transformation. The transformations are found to be reversible, and by removing the applied field, flagella restore the original shape. This result can be considered to be an indication that conformations of molecules can artificially be controlled by an electrostatic field through which biological activity of protein may be controlled