[Search, isolation and study of restrictases].

New Class II restrictases were searched in over 800 microorganisms by using a highly sensitive toluene microtechnique developed in the laboratory. This enabled site-specific endonuclease activity to be revealed in 72 strains. Thirty two new restriction endonucleases were identified, which were highly purified and contained no impurities of nonspecific nucleases, phosphatases. Many of them (LpII, PaeI, PaeBI, ApiI, CsiAI, BavAI, BavAIII, BbvAI, etc.) are of interest for use in molecular genetic studies. Corynebacterium species cells were used to isolate a new supercoarse hissing restrictase CsiBI that recognizes the 8-nucleotide site GGGGGGGG (the isoschizomer NotI) and a fine tool for obtaining enlarged fragments of pro- and eukaryotic genome.