[Site-specific endonucleases LplI and AagI].

New site-specific endonucleases LplI and AagI have been isolated from the Lactobacillus plantarum and Achromobacter agile cells, respectively. The enzymes' purification stages included treatment of cell-free extracts with polyethylenimine, fractionation in two-phase system by Albertsson's method, chromatography on blue Sepharose and DEAE-cellulose. The results of cleavage of a 5'-32P-labelled oligodeoxynucleotide duplex by restriction endonucleases LplI and AagI indicate that these enzymes recognize and cut the sequence AT decreases CGAT, being therefore true isoschizomers of the ClaI restriction endonuclease from Caryophanon latum.

[Isolation and characteristics of new restriction endonucleases from Haemophilus influenzae].

Various strains of Haemophilus influenzae have been examined for the presence of site-specific endonuclease activities, and eleven restriction endonucleases have been isolated from seven strains. For all the endonucleases recognition sequences were determined, for three of them cleavage sites being identified. The enzymes proved to be isoschizomers of known endonucleases, viz.

[A new specific endodeoxyribonuclease from Escherichia coli RFL 72].

A restriction endonuclease Eco72I with a novel substrate specificity has been isolated from Escherichia coli strain RFL 72. The enzyme recognizes (Formula: see text) hexanucleotide palindromic sequence and cleaves it, as indicated by the arrows, to produce blunt-ended fragments.