Orientation and transformation of flagella in electrostatic field

Electrostatic orientation and electrically induced transformation of bacterial flagella are 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 of flagella under an electrostatic field is studied, and by measuring the time constant of orientation, the magnitude of the dipole moment induced by the external field is estimated. By further raising the field intensity, observations on the electrostatically induced transformation are made. The transformations are found to be reversible, and when the applied field is removed, flagella return to the original shape. This result indicates that conformations of molecules can artificially be controlled by an electrostatic field, through which biological activity of protein can be controlled.<>