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Biomedical subjects

A A Baev

Publications and source records attributed to A A Baev.

At least 19 recordsLinked to original sources
PubMed1990

[Structure of the Pseudomonas aeruginosa recA gene].

The nucleotide sequence of the 1206 bp fragment of Pseudomonas aeruginosa DNA coding for the recA gene has been determined. This structure was shown to contain an open reading frame corresponding to a protein with m.w. 36808 D highly homologous (70%) to the Escherichia coli recA protein. Homology on the DNA level is significantly lower (57%) due to the high G/C content characteristics of Pseudomonas DNA. Making use of S1 nuclease and reverse transcriptase it was shown that in P. aeruginosa and E. coli cells recAPA gene transcription starts from A or T unit. Unlike "-35" region, "-10" region is homologous to the consensus E. coli promoter sequence. Comparison of primary structures of the recAPA and recAEC proteins demonstrates that the recAPA protein is by 7 amino acid residues shorter and differs from recAEC at 108 positions. Homology is the lowest in the C-terminal part. Basing on the analysis of hybrid recAPA proteins with a modified C-terminal part, it may be suggested that C-terminus is nonessential for main activities of the recA protein.

Amino Acid Sequence↗
PubMed1989

[Isolation, purification and properties of restrictase and methylase BstN1 from Bacillus stearothermophilus].

Restriction-methylation enzymes BstN1 from Bacillus stearothermophilus were isolated and purified. These enzymes are related to a new class of restriction-methylation enzymes of the second type, whose modifying component is N4-cytosine-DNA-methylase. Both enzymes recognize the DNA sequence CC(A/T)GG. Restrictase BstN1 is a protein made up of one subunit with a molecular mass of 25 kDa. The molecular mass of native DNA-methylase BstN1 is about 55 kDa. The temperature optima for restrictase and methylase BstN1 are around 60 degrees C. Possible uses of BstN1 restriction-methylation enzymes for the analysis of cytosine methylation in bacterial and higher plant DNA are discussed.

Base Sequence↗
PubMed1979

[Isolation and properties of DNA-cytosine-methylase I from Escherichia coli MRE 600].

DNA-cytosine-methylase I was isolated and purified to homogeneity. The yield made up to about 30% of total activity. The enzyme molecular weight as determined by centrifugation in a sucrose gradient, by gel filtration and by electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate was found to be 45,000. The Michaelis constant was 1,8 . 10(-6) M for SAM and 2 . 10(-4) M for DNA. DNA-cytosine-methylase I modifies phage lambda DNA in 60 sites. This modification does not protect DNA from the effects of restriction endonucleases HpaII and BsuRI. The enzyme methylates DNA in the nucleotide sequence: 5'...Pur-MC-C-G-G-Pyr...3'.

DNA (Cytosine-5-)-Methyltransferases↗
PubMed1979

[Isolation and properties of DNA-cytosine-methyltransferase EcoRII and E. coli K12].

The methods of isolation and partial purification of two DNA-cytosine-methylases (DC-methylases) EcoRII and E. coli K12 are described. After chromatography on phosphocellulose the enzymes were purified 100-fold, the yield being 30%. Further purification of the enzymes was performed by sedimentation in a sucrose concentration gradient. Both enzymes have native molecular weights of 50,000; DC-methylase from E. coli K12 may simultaneously occur in the forms with molecular weights of 70,000, 90,000 and 110,000. Both DC-methylases modify identical nucleotide sequences of DNA, have equal numbers (90) of methylation sites in phage lambda DNA and provide in vitro a complete protection of phage lambda DNA against restriction endonuclease EcoRII. DC-methylases E. Coli K12 and EcoRII differ in their chromatographic behaviour on phosphocellulose and capacity to form compexes with the cell DNA-adenine-methylase.

Coliphages↗