Thresholds in field-induced reactions of linear biopolymers

摘要: We have analysed the field-induced conformation change of DNA by absorbance measurements at magic angle. Conformation changes are observed when electric field strength exceeds a clearly defined threshold value. The values increase with increasing salt concentration and show linear dependence upon logarithm ionic strength. Measurements homogeneous samples different chain lengths N that increases decreasing N; given is function N. value for circular molecule length Nc fits to these data an effective Nc/2. This result indicates maximal extension important reaction suggests, together other results, mainly driven polarization ion atmosphere along axis DNA. Some also dynamics reaction: high pulses first step fast destacking tilting bases followed slow unwinding process. For short almost completely reversible characteristic time constant about 3 microseconds back reaction.