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N N Sokolov

Publications and source records attributed to N N Sokolov.

At least 19 recordsLinked to original sources
PubMed1999

N-terminal truncated cytochrome P450 2B4: catalytic activities and reduction with alternative electron sources.

It was shown that riboflavin binds to the truncated cytochrome P450 2B4 and forms a complex with the K(d) = 26 microM. Noncovalent complex of truncated (Delta2-27) cytochrome P450 2B4 with riboflavin was essential for electron transfer realization and catalyzed the NADH-dependent and hydrogen peroxide-supported monooxygenase reactions of aminopyrine N-demethylation and aniline p-hydroxylation. Flavocytochrome molecular maquette was capable of supporting photoactivatable electron transfer and could be photoreduced and electroreduced quantitatively in the absence of pyridine nucleotides.

Aminopyrine↗
PubMed1998

Isolation and characterization of CspBI, a novel NotI isoschizomer from Corynebacterium species B recognizing 5'-GC/GGCCGC-3'.

Sixty-seven bacterial strains were surveyed for the presence of type II restriction endonucleases, especially concerning super-rare-cutting enzymes. Fourteen strains were found to contain specific enzymes. One of them CspBI from Corynebacterium species B was purified and characterized as an isoschizomer of NotI, which recognizes the palindromic octanucleotide sequence 5'-GC/GGCCGC-3' and cleaves at the position shown by the arrow. A comparison between the cleavage patterns on different DNAs, obtained with partially purified endonucleases from other detected producents including some strains of Corynebacterium, Cellulomonas and Rhizobium has shown that these enzymes do not belong to super-rare-cutting restriction endonucleases.

Binding Sites↗
PubMed1998

[Isolation and specificity of novel restriction endonucleases Bsp40091 and AsiI, isoschizomers of BamHI].

New type II restriction endonucleases AsiI and Bsp40091 are detected in Azotobacter species N55 and Bacillus species 4009, respectively. Purified preparations of the restriction enzymes free from interfering nucleases and phosphatases were obtained by column chromatography on phosphocellulose and heparin-sepharose (Asil) and phosphocellulose and DEAE-cellulose (Bsp40091). The yield of purified AsiI and Bsp40091 was 16 x 10(3) and 8 x 10(3) units per g of wet cells, respectively. The above restriction endonucleases recognize the 5'-G decreases GATCC-3' sequence on double-stranded DNA and cleave it as shown, thus being true isoschizomers of BamHI restriction endonuclease.

Azotobacter↗
PubMed1998

[Novel site-specific endonucleases from Brevibacterium species].

New site-specific endonucleases BecAI and BecAII have been detected in Brevibacterium species A. Endonuclease BecAII free from contaminating nonspecific endonucleases, exonucleases, and phosphatases was isolated by column chromatography on phosphocellulose, heparin sepharose, and DNA cellulose. It recognizes and cleaves the 5'-GG decreases CC-3' sequence and is a true isoschizomer of HaeIII restriction enzyme. The other restriction endonuclease, BecAI, cleaves Ad2 DNA at least by 2 sites but not the DNA of phage lambda, T7, SV40, phiX174, and plasmides pBR322 and pUC19. The substrate specificity of BecAI indicates its appurtenance to the super rare restriction endonucleases.

Brevibacterium↗
PubMed1996

[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 7.6-8.2, and 5-10 mM MgCl2 under a high ionic strength (50 mM Tris-HCl, 100 mM NaCl). The site-specific endonuclease BcuAI was found to recognize the 5' G decreases G(A/T)CC sequence in double-stranded DNA and cleave it as shown with the arrow, thus being a true isoschisomer of the AvaII restriction endonuclease.

Bacillus cereus↗
PubMed1995

[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.

Bacteria↗
PubMed1994

[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. The yields of BciBI and BciBII were 600 and 10,000 U/g of cells. It was found that restriction endonucleases BciBI and BciBII are isoschizomers of ClaI and BstNI, respectively.

Bacillus↗
PubMed1994

[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. species F, are shown to be true isoschisomers of BspMII (Kpn2I) and Sau3AI, respectively.

Bacillus↗
PubMed1992

[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 8.0 and 8.5, MgCl2 concentration in the range of 5-10 mM and at the low ionic strength. It is shown that the enzyme cleaves the sequence G'GYPC'C, with the preferential cleavage of GGTACC and GGCACC sites as compared with GGTGCC and GGCGCC. Thus, the restriction endonuclease BbvBI is a true isoschizomer of nuclease BanI.

Bacillus↗
PubMed1992

[Immobilization of EcoR1, Pae1 and Lpl1 restriction enzymes].

In search for sorbents (silica gels, styrene-divinylbenzene copolymers), for immobilization of some restriction endonucleases, derivatives of trityl-containing silochroms are shown to bind EcoRI, PaeI and LplI endonucleases with the retention of 10-20, 60-70 and 40-60% activity, respectively. The immobilized restriction endonucleases have the unchanged substrate specificity, can be used several times and are stable at storage. Tritylaminopropylsilochrom is suggested to be the sorbent of choice.

Bacteriophage lambda↗
PubMed1991

[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. BcoAI recognizes the sequence 5' CAC decreases GTG 3' on double-stranded DNA and cleaves it as indicated by the arrow to yield blunt-ended DNA fragments. Thus, BcoAI is a true isoschizomer of PmaCI from Pseudomonas maltophila C.

Autoradiography↗
PubMed1990

[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. The L. plantarum strain has 400 fold endonuclease productivity as compared with the ClaI producent and is perspective for preparative isolation of LplI.

Alcaligenes↗
PubMed1989

[Current approaches to the search for new restriction endonucleases].

The main methodological approaches to the search of new restriction endonucleases are reviewed. These methods include obtaining acellular extracts by ultrasonic desintegration of microbial cells, osmotic shock effects, the effects of organic solvents, mechanical disruption of bacterial cells, biphase division after Albertson and others. The resolving power of any method discussed depends mainly on the level of restriction endonuclease activity, the presence of nonspecific endonucleases in the biomass, the presence of exonucleases and the taxonomy of the used microorganisms.

DNA Restriction Enzymes↗