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S V Mamaev

Publications and source records attributed to S V Mamaev.

28 records · Page 2Linked to original sources
PubMed1988

[Complementary-addressed modification of a single-stranded DNA fragment with an iron-porphyrin oligonucleotide derivative].

Hemin was attached covalently to the 5'-terminus of the 14-mer d(pTGACCCTCTT.CCC)rA and was shown, in the presence of oxygen and a reducing agent, to be active in the cleavage of the complementary sequence (position 261-274) in a 303 nucleotide-long DNA fragment. The yield of the cleavage products reached approximately 50%, the cleavage locus comprising two bases (G275 and G276).

DNA, Single-Stranded↗
PubMed1987

[Effectiveness of the modification of a single-stranded DNA fragment by alkylating derivatives of oligonucleotides].

Modification of a single-stranded DNA fragment 303 nucleotides long with addressed reagents d(pTGACCCTCTTCCC) A greater than CHRCl (I), d(pACCCTCTTCCC) A greater than CHRCl (II), d(CCTCTTCCC) A greater than CHRCl (III) and d(TCTTCCC) A greater than CHRCl (IV) complementary to the sequence 261-274 has been studied. It was shown that not only G258 residue, located near to the above sequence, but also G179 residue is modified. The latter can be explained by the vicinity of G179 and the alkylating group in the three-dimensional structure of the complex. Some modification of fragment 19-24 was observed due to non-complementary binding of the reagent. Association constants of the reagents (I)-(IV) with 261-274 sequence of the fragment were calculated using the dependence of the modification extent of G258 and G179 on the reagent concentration. The constants at 25 and 35 degrees C were found to be 260 and 31 (I), 0,5 and 2 (II), 0,46 and 0,13 (III), 0,0020 and 0,0023 (IV) microM-1.

Alkylating Agents↗
PubMed1986

Complementary addressed modification and cleavage of a single stranded DNA fragment with alkylating oligonucleotide derivatives.

A single stranded DNA fragment was modified with alkylating derivatives of oligonucleotides complementary to a certain nucleotide sequences in the fragment. The derivatives carried aromatic 2-chloroethylamino groups at their 3'- or 5'-terminal nucleotide residues. Some of the derivatives carried both alkylating group and intercalating phenazine group which stabilized complementary complexes. It was found that these oligonucleotide derivatives modify the DNA fragment in a specific way near the target complementary nucleotide sequences, and the DNA fragment can be cleaved at the alkylated nucleotides positions. Alkylating derivatives carrying phenazine groups were found to be the most efficient in reaction with the DNA fragment.

Alkylation↗
PubMedDate not supplied

[Device-aided determination of an effective dose in x-ray studies].

The paper proposes how to determine an effective radiation dose for patients undergone X-ray examinations, which includes the estimation of the size of a field while measuring the superficial dose and the assessment of an experiment protocol by taking into account the X-ray receiver used to measure exposure.

Adult↗
PubMedDate not supplied

[Affinity modification of 80S ribosomes from human placenta by derivatives of tri- and hexauridylates as mRNA analogs].

Derivatives of 5'-32P]labeled (pU)3 and (pU)6 bearing 4-(N-2-chloroethyl-N-methylamino)benzylmethylamine residues attached to 5'-phosphates via phosphamide bond were applied to the affinity labeling of 80S ribosomes from human placenta. The reagents had normal coding properties and were fixed in the ribosomal mRNA-binding region by codon-anticodon interaction with cognate Phe-tRNA(Rhe) at P site (in the case of (pU)3 derivative) or at both A and P sites (in the case of (pU)6 one). Both reagents were found to modify only the 40S subunit. The sites of the reagents attachment to 18S ribosomal RNA were identified by blot-hybridization of the modified 18S rRNA with restriction fragments of the corresponding rDNA. They were found to be located within positions 976-1057 for (pU)6 derivative and within 976-1164 for (pU)3 one. These sites are located presumably within highly conserved parts of the eukaryotic small subunit rRNA secondary structure.

Alkylating Agents↗
PubMedDate not supplied

[Role of the lysine residues in the phenylalanyl-tRNA synthetase substrates interaction].

The effect of 2,4-pentandione on the activity of phenylalanyl-tRNA synthetase (Phe-RSase) from E. coli MRE-600 was investigated. It was shown that modification of Phe-RSase with 2,4-pentandione leads to decrease of the aminoacylation rate without an influence on the ATP--[32P]pyrophosphate exchange reaction rate. tRNAPhe protects the enzyme against inactivation. Neither L-Phe and ATP nor the analog fo aminoacyladenylate protects the enzyme against inactivation. There are no changes in Km for amino acid and ATP in the aminoacylation reaction after modification while Km for tRNAPhe decreases three times. The dissociation constant of Phe-RSase: [14C]Phe-tRNA complex increases 4--8 times after modification. It is assumed that there are some lysine residues in Phe-RSase essential for the Phe-RSase-tRNA interaction.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

[Chemical modification of the complex of tRNA Phe with phenylalanyl-tRNA synthetase from Escherichia coli].

Alkylation of E. coli tRNAPhe, bound to the cognate synthetase was investigated. The alkylating reagent is a derivative of 2-chloroethylamine: 2',3'-O-[4(N-2-chloroethyl-N-methylamino)-benzylidene]-uridine-5'-methylphosphate. It was found that the enzyme protects from the reaction D-stem (guanosine G24) and the region of juxtaposition of acceptor stem and D-stem (S4U8 and C13) in the tRNAPhe.

Alkylation↗
PubMedDate not supplied

[Chemical modification of phenylalanyl-tRNA synthetase and ribosomes of Escherichia coli with derivatives of tRNA-Phe carrying photoreactive groups on guanosine residues].

Photoreactive derivatives of tRNAPhe (E. coli) were synthesized by alkylation of the tRNAPhe with 4-(N-2-chloroethyl-N-methylamino)benzylamine and subsequent treatment with 1.4--dinitro-5-fluorophenylazide. The derivatives are active in binding with ribosomes and phenylalanyl-tRNA synthetase when the extent of modification is lower than 3 reactive groups per tRNAPhe molecule. Under irradiation the derivatives modify exclusively the beta-subunit of the phenylalanyl-tRNA synthetase.

Amines↗