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Biomedical subjects

V L Florent'ev

Publications and source records attributed to V L Florent'ev.

At least 19 recordsLinked to original sources
PubMed1990

[Compounds similar to acyclovir. VII. Attempts to construct an anti-herpetic agent (6-hydroxy-2-oxa-4-hexenyl derivatives of nucleic bases].

Based on the available data on the acyclovir's mechanism of action we attempted to predict the antiherpetic activity of 6-hydroxy-2-oxahexen-4-yl derivatives of nucleic bases. In terms of this model 9-(6-hydroxy-2-oxahexen-4-yl) guanine might be active. 6-Hydroxy-2-oxahexen-4-yl derivatives of adenine, guanine, cytosine, thymine, uracil, 1,2,4-triazole-3 and 1,2,4-triazole-5-carboxamide have been synthesized and their activity against herpes virus I investigated. The guanine derivative proved to possess rather high activity (chemotherapeutical index 8).

Acyclovir↗
PubMed1990

[Compounds similar to acyclovir. VI. Synthesis of optically active 1',2'-seconucleosides].

A convenient method is suggested of synthesis of (3R, 4R)-, (3S, 4S)- and (3R/S, 4S/R)-dihydroxy-3-hydroxymethyl-2-oxapentyl derivatives of the, cytosine, uracyl, adenine and guanine ("full" acyclic analogues of nucleosides with C1'-C2' bond cleaved) by condensation of trimethylsilyl derivatives of nucleic bases (sodium salt in case of adenine) with (3$, 4R)-, (3S )-, (3S, 4S)- and (3R/S, 4S/R)-4,5-diacetoxy-3-acetoxymethyl-1-chloro-2-oxapentanes without catalyst followed by deacetylation.

Acyclovir↗
PubMed1990

[Synthesis, conformation analysis, and antiviral activity of benzimidazole ribofuranosides].

To study the structure-biological effect correlation in the series of nucleoside analogues containing deazapurines, a number of 2-R-benzimidazole 1-beta-D-ribofuranosides (R = H, CF3, SCF3, CH2SCF3, CH2Ph, CH2CN) have been prepared by the modified silyl method. On the basis of CD and PMR data it was shown that the compounds exist in solution mainly as syn-conformers. Calculation of the furanose ring pseudorotation parameters in terms of N-S model indicates the predominance of S-population. In contrast to acyclonucleosides, the ribofuranosides obtained are nonactive against entheroviruses and more cytotoxic.

Antiviral Agents↗
PubMed1987

[Inhibition of influenza virus A RNA-polymerase activity by various 3'-amino-3'-deoxy- and 3'-azido-3'-deoxyribonucleoside-5'-triphosphates].

The effects of 3'-amino-3'-deoxy- and 3'-azido-3'-deoxyribonucleoside-5'-triphosphates on the RNA synthesis catalyzed by influenza virus A RNA polymerase were studied. All nucleotide analogues tested decreased the RNA synthesis twofold at the inhibitor: substrate ratio about 1:5 (in moles). The hypothetic mechanism of inhibitors action based on the incorporation of inhibitors into the 3'-termini of the RNA chains and subsequent blocking of the RNA chains elongation is proposed. The nucleotide analogues under investigation were several times more effective as compared with the ribavirine 5'-triphosphate, a well-known inhibitor of influenza A virus reproduction.

Azides↗
PubMed1986

[Synthesis of acyclic analogs of ribavirin].

A number of ribavirin analogues were prepared in which the ribose moiety was replaced with acyclic substituents imitating some fragments of the ribose ring: 2,3-dihydroxy-prop-1-yl, 3-hydroxymethyl-4-hydroxy-2-oxabut-1-yl, 4,5-dihydroxy-2-oxapent-1-yl and 1,5-dihydroxy-3-oxapent-2-yl. These analogues were synthesized by direct alkylation of ethyl 1,2,4-triazole-3-carboxylate with suitable agents followed by ammonolysis. New convenient methods for preparing the alkylating agents were developed.

Chemical Phenomena↗
PubMed1978

[Substrate specificity of soluble mitochondrial ATPase].

The parameters of the hydrolysis of ATP and several analogs by soluble mitochondrial ATPase were determined. Vmax of the reaction decreases within the range: 2'-desoxy-ATP greater than ATP greater than etheno-ATP greater than GTP greater than 3'-O-methylATP greater than UTP. ATP, 2'-desoxypATP, 3'O-methyl-ATP, GTP, and etheno-ATP are hydrolysed by soluble mitochondrial ATPase with close Km(app) values. CTP is not hydrolysed by the enzyme and does not inhibit the ATPase reaction at a concentration of 10(-2) M. Nucleoside triphosphate derivatives with an "open" ribose cycle 9-[1',5'-dihydroxy-4-(S)-hydroxymethyl-3'-oxapent-2' (R)-yl]adenyl-5'-triphosphate, and 1-[1',5'-dihydroxy-4'-(S)-hydroxymethyl-3'-oxapent-2'(R)-yl[cytosine-5'-triphosphate are effective inhibitors of ATPase (Ki approximately 5.10(-5)M). Mitochondrial ATPase binds the ATP analogs that have hydrocarbon radicals-(CH2)2-, -(CH2)3-, and (CH2)4- instead of the ribose residues: 9-(2'hydroxyethyl)adenyl-2'-triphosphate, 9-(3'-hydroxypropyl)-adenine-3'-triphosphate, and 9-(4'-hydroxybutyl)adenine-4'-triphosphyl)adenine-4'-triphosphate were not hydrolysed by the enzyme, although they inbibit the ATPase reaction (Ki 2.10(-4)M). 9-(2'-hydroxyethyl)adenine-2'-triphosphate is hydrolysed by ATPase eight times more slowly than ATP. It is suggested that the hydrolysis of the substrates of mitochondrial ATPase is- preceded by the binding of the substrates in a tense conformation in the active site of the enzyme.

Adenosine Triphosphatases↗
PubMed1976

[Inhibition of pyridoxal kinase by 2- and 6-alkyl substituted vitamin B6 analogues and by pyridoxal oximes].

It is shown in the system with partially purified pyridoxal kinase from mouse liver, that the presence of one alkyl group in the 2nd or 6th positions of pyridine cycle in pyridoxole and pyridoxamine derivatives and pyridoxal oximes is a necessary condition which determines relatively high affinity of structural vitamin B6 analogues to the enzyme. 2'-n-Propylpyridoxal was phosphorylated by pyridoxal kinase with a relatively high rate, while 2-nor-6-methylpyridoxal, having a similar affinity to pyridoxal kinase, was not phosphorylated at all. The data obtained indicate an important role of the methyl group in the 2nd position of pyridine cycle in vitamin B6 molecule for its fixation in the enzyme active site and for the proper orientation, which provides enzymatic substrate phosphorylation. Some structural peculiarities of vitamin B6 analogues are considered, pre-determining their low or high efficiency as vitamin B6 antimetabolite in vivo.

Animals↗
PubMed1976

[Interaction of 4-aminobutyrate-transaminase from swine kidneys with 5'- and 6'-methyl derivatives of pyridoxal-5'-phosphate].

The study of interaction of 4-aminobutyrate transaminase with 5'- 6'-methyl derivates of PLP demonstrated that only the former was capable of forming a catalytically active holoenzyme possessing 0.37 activity of the native holoenzyme and a low affinity substrates. This compound interacts with the apoenzyme at a slower rate than does PLP; it has a reduced affinity towards apotransaminase (Km = 1.10(-4) M) and is replaced from the active site by native coenzyme. The other analog of pyridoxal-5'-phosphate forms a catalytically inactive complex with the apoenzyme; the other analog is not replaced from the active center by native coenzyme and non-competitively inhibits the reconstruction of apotransaminase (Ki = 2.10(-5) M).

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

[A new approach to the synthesis of enzyme inhibitors].

On the basis of the application of transition-state theory to enzymatic catalysis a novel approach to the synthesis of inhibitors of enzymes involving conformational rigid substrate has been proposed. It is predicted that the substrates which resemble the natural species in the structure of functional groups, but posses conformational flexibility, will be bound to the enzyme more tightly and converted more slowly than the natural substrate.

Binding Sites↗
PubMedDate not supplied

[Structure of d(GT)n repeating sequences with parallel and antiparallel chains].

The ability of oligonucleotides 3'-d(GT)5pO(CH2)5Opd(GT)5-5' (anti[d(GT)]) and 3'-d(GT)5pO(CH2)6Opd(GT)5-3' (par[d(GT)]) to form hairpins and higher associates is studied. Optical methods of thermal denaturation and circular dichroism as well as the fluorescence of ethidium bromide and acridine orange bound to oligonucleotides were used. At room temperatures the formation of hairpin structure with parallel and antiparallel strands is possible. Thermodynamic parameters of par[d(GT)] and anti[d(GT)] are similar and equal to delta H = -15 kcal/mol, delta S = -50 cal/mol. deg. In the temperature range 3-10 degrees C par[d(GT)] and anti[d(GT)] form four-stranded structures with parallel chains, in which layers of four G-residues alternate with unpaired T-residues being bulged out easily. On comparison of occurrence of alternating (GT)n, (GC)n and (G)n sequences in genome it can be stated that (GT)n biological functions could be connected with conformational possibilities of the four-stranded parallel structures with unpaired T-residues.

Circular Dichroism↗
PubMedDate not supplied

[Four-stranded complexes of oligonucleotides--quadruplexes].

The review presents analysis of the experimental, model and calculation studies concerned with the formation of the four-stranded helices of the natural and synthetic oligonucleotides. Guanine-rich oligonucleotides form stable four-stranded helices. Structures of such complexes were investigated by means of X-rays and spectrographic methods. These works have been reviewed in the first part. There are three possible variants of noncanonical structures formed by oligoguanylic acids. Two of them--four-stranded helices differed by the mutual direction of the sugar-phosphate chains. The third one is the two-stranded hairpin. Regulation of the number of cellular processes by means of the structural conversions between these three forms of guanine-rich motifs are investigated in articles reviewed in the second part. These works are concerned with the structural organization and functions of telomers, and on the other hand with the possible role of quadruplexes in self-recognition processes of the four homologous chromatids during meiosis and the following recombination. The third part of the review considers quadruplexes with an arbitrary sequence. In general there are model works inspired by investigations of recombination and replication processes. Experimental data concerned with the formation of quadruplex structures from two decamer Watson-Crick base paired duplexes oligo(dA).oligo(dT) are also presented.

Nucleic Acid Conformation↗
PubMedDate not supplied

[DNA sequencing by hybridization with an oligonucleotide matrix (SHOM). The theory of DNA elution after hybridization].

The theoretical treatment of the process of washing out of a single stranded DNA fragment after hybridization with short oligonucleotides immobilized within the polyacrylamide gel layer is presented. The theory describes satisfactorily the main body of experimental findings, obtained earlier in connection with the elaboration of a new DNA sequencing method based on hybridization with the matrix of immobilized oligonucleotides [K.R. Khrapko et al.@J. DNA Sequencing Mapp. 1991. V. 1. P. 373-388]. In particular the theory explains and describes well quantitatively the observed dependence of the "washing off temperature" Tw on the concentration of the immobilized oligonucleotides. The Tw dependence on inherent physico-chemical parameters such as the enthalpy and the entropy of duplex formation and on those selected by the experimenter (washing time duration, the gel thickness etc.) is also considered. A simple approximate expression for the calculation of "washing off temperature" is given. Some inconsistencies between calculated and observed washing curves are discussed.

Base Sequence↗