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V V Butkus

Publications and source records attributed to V V Butkus.

11 recordsLinked to original sources
PubMed1990

[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. Hin1 I, Hin8 I--Acy I; Hin1 II, Hin8 II--Nla III; Hin2 I, Hin5 I--Hpa II; Hin3 I--Cau II; Hin5 II--Asu I; Hin5 III--Hind III; Hin6 I, Hin7 I--Hha I. Restriction endonucleases Hin1 I, Hin1 II and Hin6 I recognize nucleotide [formula: see text] sequences 5'GRCGPYC, 5'CATG, 5'GCGC, respectively, and cleave them as indicated by arrows.

Base Sequence↗
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↗
PubMed1988

[Effect of N4-methylcytosine and 5-methylcytosine on the stability of the DNA helix].

The thermodynamic parameters (delta H, delta S) of the helix-coil transition of self-complementary oligonucleotides d(CGCGCGCG), d(CG5mCGCGCG), d(CG4mCGCGCG), d(GGACCCGGGTCC), d(GGA5mCCCGGGTCC), and d(GGA4mCCCGGGTCC) were determined. The substitution of 4mC for C was found to decrease the melting temperature of the oligonucleotides. The destabilization effect of the two substitutions is equivalent to the change of A.T for G.C pair. The free energy decrease of the helix-coil transition due to the introduction of two 4mC into an octanucleotide was estimated to be 1,24 kcal/mol.

5-Methylcytosine↗
PubMed1987

[Purification and substrate specificity of BcmI restriction endonuclease].

A strain producing the new specific restriction endonuclease BcmI has been found in the Bacillus generum. The enzyme has been purified by chromatography on the blue sepharose, phosphocellulose PII, heparin sepharose. The analogous purification has been obtained when the blue sepharose has been substituted for the orange sepharose, the home produced sorbent. The BcmI enzyme has been shown by the substrate specificity definition to be an isoschizomer of the restriction endonuclease ClaI.

Bacillus↗
PubMed1985

Characterization of restriction-modification enzymes Cfr13 I from Citrobacter freundii RFL13.

This communicatiopn describes some properties of RCfr13 I and MCfr13 I, isolated from Citrobacter freundii RFL13. RCFfr13 I restriction enzyme recognizes the 5'-G GNCC sequence and cleaves, as indicated by the arrow. MCfr13 I methylase modifies the internal cytosine producing m5C (5'-GGNm5CC). RCfr13 I is sensitive not only to this type of substrate modification but also to hemimethylation in overlapping sites by MCfr10 I (internal cytosine of RCfr13 I recognition is methylated) and MHpa II (external cytosine is methylated). From these results the sensitivity of RCfr13 I to methylation by dcm methylase of E.coli in overlapping sites is deduced.

Bacteriophage lambda↗
PubMed1985

Analysis of products of DNA modification by methylases: a procedure for the determination of 5- and N4-methylcytosines in DNA.

Although many different methods are used for the identification of methylated heterocyclic bases in DNA not all of them possess the ability to discriminate N4-methylcytosine (m4C) and 5-methylcytosine (m5C). Therefore, some of the methods need additional reexamination. This paper reinvestigates some chromatographic systems (thin-layer chromatography, paper chromatography, electrophoresis) most widely used in the analysis of minor bases occurring in nucleic acids according to their ability to separate m4C and m5C. A simple procedure for the preparation of the sample and a chromatographic system for its analysis was developed. The recommended chromatographic systems may be used for the simultaneous separation of not only of m4C and m5C but also both methylated cytosines together with N6-methyladenine and 7-methylguanine.

5-Methylcytosine↗
PubMedDate not supplied

[Mycoplasma restriction-modification system MunI and its possible role in pathogenesis processes].

The restriction-modification system, named RMMunI, has been purified and characterised from Friend murine erythroleukemia cells. The site-specific endonuclease recognizes and cleaves the 5'C1AATTG nucleotide sequence. RMunI is an isoschizomer of RMfeI from Mycoplasma fermentans. Site-specific methylase modifies the second adenine residue in the same sequence (5'Cam6ATTG). It was established that the discovered enzymatic system is from mycoplasma which contaminates cell lines. Mycoplasma's DNA hybridizes with species-specific DNA probed for Mycoplasma fermentans and Mycoplasma arginini. The possible role of mycoplasmic restriction-modification enzymes in the process of acquired immune deficiency syndrome are discussed.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[B-A and B-Z transitions in deoxyoligoduplexes containing 4- and 5- methylcytosine].

Self-complementary oligodeoxynucleotides: GGACCCGGGTCC, GGA4mCCCGGGTCC, GGA5mCCCGGGTCC, CGCGCGCG, CG4mCGCGCG, CG5mCGCGCG were synthetized to study the contribution of methyl groups into the energetics of the three known cooperative transitions in DNA: helix-coil, B-A and B-Z With the use of circular dichroism and absorbtion methods the profiles of the above transitions were obtained by variation of temperature (helix-coil), trifluoroethanol fraction (B-A), NaCl and trifluorethanol contents (B-Z). On the basis of the transition widths and shifts of the transition points due to the methylations the energetics of the methyl groups was estimated. 5mC stabilizes the B form relatively the A form by 0.33 kcal/mol; while 4mC by 0.5 kcal/mol. In the B-Z transition 5 mC stabilizes the Z form by 0.28 kcal/mol relatively the B form; 4mC stabilizes also the Z form although by 0.14 kcal/mol only. Thus, these naturally occurring modifications could modulate substantially the ability of a DNA piece to shift into the A or Z form.

5-Methylcytosine↗
PubMedDate not supplied

[Specificity of action of DNA methylases BcnI, CfrI and Cfr10I].

The site specificity of three DNA methylases BcnI, CfrI and Cfr10I was determined to be 5'Cm4C(C/G)GG, 5'PyGGm5CCPu and 5'Pum5CCGGPy, respectively. Using the modification methylases under investigation with known restriction endonucleases, fourteen new DNA cleavage specificities can be created. Some aspects of the use of restriction endonucleases in DNA methylation analysis are discussed.

Bacillus↗