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L L Kiselev

Publications and source records attributed to L L Kiselev.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

[20 years of cooperation in the study of structure and function of tRNA and aminoacyl-tRNA-synthetases].

The article reviews the results of joint projects initiated 20 years ago in the field of tRNA and aminoacyl-tRNA synthetases. Laboratories located at Novosibirsk, Moscow, Kiev and other places remoted geographically effectively cooperated with each other. More than 30 common publications emerged and the data obtained were communicated at several international meetings. The effectiveness of cooperation was achieved by two important factors: (i) mutual scientific and methodological complementarity of the cooperating units, and (ii) absence of administrative pressure. The cooperation was strongly supported by the Scientific Council of Molecular Biology and 10 workshops were sponsored by the Council to facilitate personal contacts and to create an atmosphere of intensive and informal exchange of data and ideas. It is stressed that the experience worked out in this particular field is applicable to other fields of molecular biology.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

[Regions of human genome containing analogs of oncogenes and retrovirus genes. I. A family of c-mos genes and unusual structure of ORA-gp5 locus].

The structural organization of a number of recombinant phages previously selected from the human gene library has been studied. On the basis of comparison of physical maps and hybridization to cloned probes it was deduced that different human loci with the homology to v-mos are represented in lambda recombinants. The physical map of the cloned region of the human genome designated as ORA-gp5 was constructed. The sequences of three different genetical elements v-mos-related oncogene, mammalian type C retrovirus and Alu type repeat are interspersed in this structure. The hypothesis concerning the probable origin of this locus has been proposed. The mosaical structure of ORA-gp5 could be the result of the integration of mammalian retrovirus in the vicinity to c-mos gene with subsequent recombination and transposition. The resulting potentially oncogenic structure was later inactivated by the integration of Alu-type repeats.

Animals↗
PubMedDate not supplied

[Role of the anticodon in recognition of tRNA by aminoacyl-tRNA-synthetases].

The nucleic acid-protein interactions are considered for mutual recognition of transfer RNAs and cognate aminoacyl-tRNA synthetases. The validity of the first recognition hypothesis (1964) which postulated the participation of anticodons in this process has been proved both for prokaryote and eukaryote tRNA species. This conclusion stems from numerous data obtained by means of different methodological approaches. These experimental observations concern the majority of tRNAs belonging to the main structural class of tRNAs with a short variable loop. Structural basis of recognition for some tRNAs (with long variable loop) remains obscure.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

[Mechanism of functioning of aminoacyl-tRNA-synthetases].

The article reviews the data available concerning the kinetics of reactions catalysed by eukaryotic and procaryotic aminoacyl-tRNA synthetases (E.C.6.1.1). It is shown that most of these enzymes operate in accordance with the flip-flop mechanism although individual variations do exist. It is stressed that a simplified kinetic approach of Cleland is inappropriate if applied to the aminoacyl-tRNA synthetases where subunit interactions are involved in the overall kinetics. The fidelity of aminoacylation reaction depends not only on the proofreading mechanisms at catalytic centres but also on the contribution of mutual conformational changes induced in interacting subunits of the synthetases.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

Dimensions of homo- and heteropolymeric sections of DNA synthesized by reverse transcription from globin mRNA matrices.

The lengths of globin messenger RNAs, isolated from rabbit and pigeon reticulocytes, and single-stranded complementary DNAs, synthesized from mRNA in presence of RNA-directed DNA-polymerase and oligo(dt) have been investigated by polyacrylamide gel electrophoresis under denaturing conditions. The cDNA preparations contained a fraction which corresponded in length to the alpha and beta chains of the mRNA used as a matrix. The lengthwise distribution of poly(A) sequences, isolated from globin mRNAs, corresponded to a statistical distribution, with a maximum at 75-80 nucleotides and with a maximum length of approximately 150 nucleotides. The lengthwise distribution of poly(dt) sequences, isolated from cDNA, corresponded to the poly(A) sequence distribution. It was concluded that: 1) cDNA is heterogeneous with respect to the length of poly(dt) sequences located at the 5' end of the molecule; 2) there was no selective use as primer of only that oligo(dt) which was located within the complex formed with the 5' end of the mRNA poly(A) sequence; 3) the heterogeneity of poly(DT) corresponded qualitatively to two models of template-primer interaction: selective use as a true primer of the oligonucleotide located in the complex formed with the 3' end of mRNA, and a statistical distribution of primer along the poly(A) sequence; and 4) the heterogeneity of the homopolymeric section of the cDNA may affect the kinetics of hybridization with mRNA, which possibly explains the previously observed [1] anomalous dependence of the hybridization rate on time.

Animals↗
PubMedDate not supplied

[Increasing specificity of tryptophanyl-tRNA synthetase after amino acid activation].

It is shown for beef pancreas tryptophanyl-tRNA synthetase that there exists a mechanism which provides additional discrimination in vitro after misactivation of monofluorinated tryptophan analogs. In the presence of tryptophan one can observe a rapid decomposition of noncognate aminoacyl adenylate-enzyme complexes containing 4-fluoro-, 6-fluoro- or 7-fluorotryptophan residues, whereas the stoichiometry aminoacyl adenylate.enzyme complexes with tryptophan and 4-fluorotryptophan residues is not changed. Rejection of noncognate aminoacyl adenylate-enzyme complexes is connected neither with the enzymatic hydrolysis of aminoacyl adenylate nor with the competition of non-cognate aminoacyl adenylate and the added amino acid for the enzyme binding site. Rejection of noncognate complexes is presumably caused by the interaction between the active centers localized on two subunits, with one of them being occupied by an amino acid molecule and the other one by noncognate aminoacyl adenylate.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

[Role of zinc ions in the functioning of bovine tryptophanyl-tRNA-synthetase].

By means of atomic absorption spectroscopy up to 0.9 Zn2+ atom per molecule of bovine tryptophanyl-tRNA-synthetase (E. C. 6.1.1.2) was found. Treatment of the enzyme with orthophenanthroline (Zn2+-chelating agent) or prolonged dialysis leading to the removal of bound Zn2+ causes inactivation of the enzyme whereas the addition of Zn2+ reactivates it. Kinetic analysis of the inhibiting action of orthophenanthroline at various concentrations of tryptophan, ATP and tRNA leads to the conclusion that removal of Zn2+ prevents the binding of the ATP molecule to tryptophanyl-tRNA-synthetase. By means of chemical modification it is shown that exposed histidine residues and the carboxylic groups of the enzyme participate in Zn2+ binding. According to circular dichroism data removal of Zn2+ has no influence on the secondary structure although some local alterations of the ternary structure are revealed.

Adenosine Triphosphate↗