  The long time dynamics of the conformational transition from B-DNA to Z-DNA
is shown to undergo a dynamic phase transition. We obtained the dynamic phase
diagram for the stability of the front separating B and Z. The instability in
this front results in two split fronts moving with different velocities. Hence,
depending on the system parameters a denatured state may develop dynamically
eventhough it is thermodynamically forbidden. This resolves the current
controversies on the transition mechanism of the B-DNA to Z-DNA.
