we found that in the presence of dmso ( 10 % v/v ) , the superhelical cleavage of pbr322 dna by restriction endonucleases saci and ecori proceeds with extensive accumulation of an intermediate , the single-nicked circular dna , while with pvuii endonuclease the superhelical form is converted directly to the linear form .
C0012937
superhelical
C0012925
circular dna