Application of restriction endonucleases as a tool for studying the action of 4-S-ethanolsulfido-cyclophosphamide on DNA with known sequences.

Lambda-DNA and plasmid pBR 322-DNA, respectively, were treated in vitro with increasing amounts of 4-S-ethanolsulfido-cyclophosphamide (CPA-P1). Subsequent digestion with restriction endonuclease Pvu II or Mbo II revealed discrete alterations in the cleavage patterns as compared to the controls, indicating subtle changes in DNA structure due to CPA-P1 interaction. In the case of pBR 322-DNA the CPA-P1 treatment of supercoiled circular DNA was more inhibitory to subsequent digestion as compared to the treatment of linearized plasmid DNA molecules.