PERIODIC MOTION OF LARGE DNA-MOLECULES DURING STEADY FIELD GEL-ELECTROPHORESIS

Direct observation of individual T4 DNA molecules during steady field gel electrophoresis was carried out with fluorescence microscopy. Stat istical analyses of the image data show that (i) DNA molecules change their conformation and velocity periodically even under a steady field , (ii) the characteristic time of the periodic motion decreases with a n increase of the electric field and with a decrease of the gel concen tration, and (iii) the rear end of DNA shows a periodic stick-slip mot ion, while the front end moves with almost constant speed. A possible interpretation for the periodic behavior is presented.