MIGRATION OF SINGLE-STRANDED-DNA IN POLYACRYLAMIDE GELS DURING ELECTROPHORESIS

By using fluorescence recovery after photobleaching (FRAP) and electri c birefringence, the migration of single-stranded DNA in polyacrylamid e gels and orientation as a response to an electric pulse were investi gated. Electrophoretic mobility is in good agreement with the model of biased reptation including fluctuations. The determination of the ele ctrophoretic mobility in solution, Cc,, allows an estimation of the ge l pore diameter seen by the molecule. As previously observed for doubl e-stranded DNA, the electric birefringence results from two processes: the alignment of the molecule along the electric field and the elonga tion of the primitive path in the gel, for long single-stranded DNA (> 2000 bases). The combination of results obtained with the two techniq ues allows us to propose experimental conditions to improve the separa tion of single-stranded DNA with pulsed field techniques.