[Site-specific BcuAI endonuclease from Bacillus cereus A].

A new restriction endonuclease was isolated from the Bacillus cereus BKM B-814 by means of the cell disruption with ultrasonication, ammonium sulfate fractionation of the cell-free extract, and chromatography on DEAE-Sepharose to give about 1400 U of the enzyme per gram of cells. The enzyme revealed the maximum activity at 30-37 degrees C, pH 7.6-8.

[Bsp153AI and BspM39I--new isoschizomers of PvuII restriction enzyme].

New restriction endonucleases, Bsp153AI and BspM39I, were isolated from Bacillus species strains 153A and M39, respectively. The enzymes recognize and cleave the nucleotide sequence [sequence: see text] and are true isoschizomers of restriction endonuclease PvuII.

[New site-specific endonucleases from strains of Bacillus].

In a search for new restriction endonucleases type II, among forty bacterial strains of the Bacillus genus two strains producing site-specific endonucleases have been found. Endonucleases BbvAIII and BspFI, isolated from B. brevis BLM B-677 and B.

[Isolation, purification, and characteristics of the new restriction enzymes BciBI and BciBII, produced by Bacillus circulans].

New site-specific endonucleases BciBI and BciBII have been detected in Bacillus circulans. The enzymes were purified by fractionation of cell-free extract with polyethylene imine and ammonium sulphate (40-80% of saturation) followed by chromatography on DEAE-sepharose, blue-sepharose and phosphocellulose. The endonucleases BciBI and BciBII were separated only at the final step of the purification--by chromatography on the phosphocellulose column.

[Specific endonuclease BbvBI from Bacillus brevis].

A new restriction endonuclease BbvBI free from contaminating nonspecific nucleases and phosphatases was isolated from the Bacillus brevis cells. The enzyme was purified by fractionating the sonicated cell-free extract in a two-phase PEG/dextran system and subsequent chromatographies on DEAE-sepharose, blue sepharose and heparin sepharose. The endonuclease BbvBI displayed the maximal activity at 45 degrees C, pH between 8.

[BsoAI--a new site specific endonuclease from Bacillus coagulans].

A new site-specific endonuclease was detected in toluene lysates of Bacillus coagulans AUCM B-732 and designated as BcoAI. The enzyme was purified by fractionation of the cell-free extract in the two-phase PEG/dextran system followed by chromatography on DEAE-sepharose and phosphocellulose and shown to be free of nonspecific nucleases and phosphatases. BcoAI has three cleavage sites on lambda DNA, but does not cleave SV40, pBR322 and pUC19 DNA.

[The effect of monovalent cations on the activity of site-specific endonuclease PaeII].

Activity of restrictase Pae II, contrary to known restriction enzymes of the II class (except of true isoshizomere Sma), depended absolutely on monovalent cations. This pattern is untypical for restrictases of the II class. At the same time, restrictase Pae II was able to hydrolyze DNA as a substrate in absence of exogenous Mg2+, in the incubation mixture contained cations K+, Rb+, Cs+ and NH4+ but not Na+ or Li+.

[The search for strains producing new restriction endonucleases].

The search for restrictases in 154 strains belonging to 104 species of 32 genera of microorganisms has been carried out by the method of rapid toluene assay. In 10 strains the activity of endonucleases specifically fragmenting the DNA of phage lambda in the presence of Mg2+ ions has been detected. Restrictases Pae I and Pae II formed by two Pseudomonas aeruginosa strains have been identified as the true isoschizomers of restriction endonucleases Sph I and Sma I respectively.

[Effect of thiol-specific reagents on the activity of PaeI and PaeII restrictases from Pseudomonas aeruginosa].

5,5'-dithiobis-2-nitrobenzoic acid, N-ethylmaleimide, and parachloromercuribenzoate have been demonstrated to inhibit the activity of restrictases PaeI and PaeII from Ps. aeruginosa bacterial cells. Restrictase PaeII was more sensitive to the action of thiol-specific reagents, as compared to PaeI.

A site-specific endonuclease from Pseudomonas aeruginosa.

PaeI, a new restriction endonuclease from Pseudomonas aeruginosa clinical strain was isolated and characterized. It recognizes and cleaves the sequence 5'-GCATG reduced C-3' generating DNA fragments with 3'-tetranucleotide sticky ends. DNAs of pBR322, SV40 and bacteriophage lambda have one, two and six PaeI recognition sites, respectively.