A restriction endonuclease having one DNA binding site is proposed, synthesized from a restriction endonuclease that has one C-terminal domain and one N-terminal domain and two DNA binding sites, by proteolytic cleavage into the two domains or by cloning the gene segment that codes for the domains and expression of the domains and selection of the endonucleolytic domains having one DNA binding site. In addition, a method of synthesis of the restriction endonuclease and its use are claimed.