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Biomedical subjects

E N Demchenko

Publications and source records attributed to E N Demchenko.

5 recordsLinked to original sources
PubMed1993

Specificity of interaction of pyrimidine oligonucleotides with DNA at acidic pH in the presence of magnesium ions: affinity modification study.

Sequence-specific alkylation of dsDNA with pyrimidine oligonucleotides bearing an alkylating group at the 3' and 5' terminal phosphates, or both, has been investigated. At pH 5.4, sequence-specific modification of guanosines of the DNA in the vicinity of the target purine-pyrimidine sequence occurs. The reactive group at the 5' terminus of the oligonucleotides attacks guanosines in the purine strand of the target DNA. The reactive group at the 3' end can interact with guanosines in both strands of the DNA. Bifunctional reagents can alkylate both strands of the DNA simultaneously. At pH 4 in the presence of magnesium ions, the oligonucleotide derivatives can form imperfect complexes with sequences homologous to the target sequence and alkylate the DNA at the corresponding positions.

Alkylation↗
PubMed1991

Sequence-specific alkylation of dsDNA with derivatives of pyrimidine oligonucleotides conjugated to 2-chloroethylamine groups.

Reaction of homopyrimidine oligonucleotides bearing a 5'-terminal alkylating aromatic 2-chloroethyl-amino group with a bovine papilloma vector expressing human interferon-gamma was investigated. The oligonucleotide derivatives bound to corresponding homopurine-homopyrimidine sequences in dsDNA and alkylated guanosine residues at these sites in the purine strand of the target. The alkylated DNA can be cleaved at the modified residues. At pH 5.4, the reaction was highly specific to the target sequences; at pH less than 5, some nonspecific reactions were observed at the sequences partially complementary to the oligonucleotides. Elongation of the linker between the alkylating group and the oligonucleotide phosphate increased the alkylation efficiency. Repeated treatment of the DNA with gradually increased concentrations of the reagent resulted in quantitative modification of the target guanosines.

Alkylation↗
PubMed1987

[Problems of selecting the reagent concentration in the solid-phase immunoenzyme method for determining antibody concentrations].

The problems of selecting the concentration of reagents with the aim of increasing the accuracy and sensitivity of reactions, as well as decreasing the consumption of reagents, are shown as exemplified by the antigen-antibody reaction of the first order. A new approach to the ELISA reaction is proposed, which makes it possible to present the totality of consecutive interactions of the reagents as block diagrams described by known mathematical expressions. The limitations of the linear dependence of the results of the reaction are shown, and the methodological recommendations for overcoming these limitations are given.

Antibodies, Bacterial↗
PubMed1987

[Construction of DNA-probes and their immunochemical detection using nonradioactive hybridization tests].

Simple and efficient chemical approaches to preparation of DNA probes carrying 2,4-dinitrophenyl, dansyl or biotin residues were developed. The residues were introduced using following DNA derivatization procedures: a) transamination of cytidine residues with O-(4-aminobutyl)hydroxylamine; b) mercuration of pyrimidine residues followed by beta-mercaptoethanol modification. It was shown that 2,4-dinitrophenyl-containing DNA probes can be used for nonradioactive hybridization detection of nucleic acids. DNP-DNA: DNA complexes were detected using mouse antibodies specific to 2,4-dinitrophenyl groups, which were developed with peroxidase-conjugated antimouse immunoglobulins. Peroxidase-catalyzed chemoluminescent reaction of luminol oxidation with hydrogen peroxide allowed to detect 10 picograms of the dinitrophenylated single-stranded DNA probe.

Biotin↗