[Isolation and structure of novel peptide inhibitor of HIV-1 integrase from marine polychaetes].

A homogeneous peptide with m683 Da which inhibits HIV-1 integrase with IC50 3 x 10(-5) M was separated from aqueous extracts of marine worm Eunicidae sp. by multi-stage chromatography purification. The structure Asp-Leu-Hse-His-Ala-G1n was proposed for this peptide according to the amino acid analysis, automated amino acid Edman sequencing, TLC with the witness and homoserine MS/MS fragmentation. The proposed structure is the first example of natural peptide containing amino acid homoserine residue.

[HIV-1 integrase inhibition by dimeric bisbenzimidazoles having different spacers].

HIV-1 integrase is responsible for one of the key steps of the viral replication, integration of the viral cDNA into the host cell genome. Integration inhibition leads to complete block of the virus replication. In this study inhibition of integration by dimeric bisbenzimidazoles DBBI(7) with heptamethylene and DBBI(8) with tri(ethylene glycol) spacers was examined, and it was learned out that IC50 for DBBI(7) was about 0.03 microM, and IC50 for DBBI(8) was about 10 microM. By using cross-linking assays, it was shown that both compounds impeded a proper disposition of DNA-substrate at the active centre of integrase. Dissociation constants for complexes between either DBBI and DNA-substrate of integrase were determined. Calculated Kd values were 270 nM and 140 nM for complexes formed by DBBI(7) and DBBI(8), respectively. Therefore, inhibition of integration does not directly result from the binding of DBBIs with DNA. The dependence of initial rates of enzymatic reaction on the DNA-substrate concentration in presence of different concentrations of inhibitors was found, and inhibition constants were determined. All the data obtained allow us to suppose that the different inhibition activity of DBBI(7) and DBBI(8) results from the different mechanism of their binding: DBBI(7) is a competitive inhibitor of integrase whereas DBBI(8) is assumed to show a more complex mechanism of inhibition.

[Interactions of HIV-1 DNA heterocyclic bases with viral DNA]. / Izuchenie vzaimodeistvii geterotsiklicheskikh osnovanii DNK VICH-1 s virusnoi integrazoi.

Human immunodeficiency virus type 1 integrase is one of three viral enzymes, and it realizes a key process of the viral replication cycle, i.e. viral DNA integration into infected cell genome. Integrase recognizes nucleotide sequences located at the ends of the viral DNA U3 and U5 LTRs and catalyzes 3'-processing and strand transfer reactions. To study the interactions between integrase and viral DNA at present work, we used modified integrase substrates mimicking the terminal U5 LTR sequence and containing non-nucleoside insertions in one or/and both strands. It is shown that the substrate modifications have no influence on the integrase binding rate, while the heterocyclic bases removal in the 5th and 6th substrate positions and in the 3rd position of the substrate processed strand distinctly inhibits the integrase catalytic activity. This fact demonstrates these bases significance for the active enzyme/substrate complex formation. On the contrary, modification of the 3rd position within substrate non-processed strand stimulates 3'-processing. Since heterocyclic base elimination results in disruption of the DNA complementary and staking interactions, this result shows that DNA double helix destabilization close to the cleaved bond promotes the 3'-processing.

[Synthesis of nucleotide derivatives containing 1-(4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzamido)-2,3-propanediol for photoaffinity modification of proteins and nucleic acid]. / Sintez oligonukleotidnykh proizvodnykh, soderzhashchikh 1-(4-(3-(triftorometil)-3H-diazirin-3-il)benzamido)-2,3-propandiol, dlia fotoaffinnoi modifikatsii belkov i nukleinovykh kislot.

1-(4-(3-(Trifluoromethyl)-3H-diazirin-3-yl)benzamido)-3-O-(4,4'- dimethoxytrityl)-2,3-propanediol phosphoramidite was synthesized and used as a modified unit in the automatic synthesis of oligodeoxyribonucleotides. Pentadecathymidylates with various numbers of 2,3-propanediol moieties substituted with aryl(trifluoromethyl)diazirinyl (ATFMD) were obtained, and the thermal stability of their duplexes with (dA)15 were studied. One ATFMD-propanediol residue was shown to reduce the thermal stability of the duplex by 8-9 degrees C. The irradiation of the ATFMD-containing duplexes by UV light with the wavelength of 350 nm was found to cause the cross-linking reaction of the ATFMD-containing strand with the complementary strand and the formation of the cross-linked duplexes. The photomodification efficiency was independent of the oligonucleotide sequence, with each ATFMD group providing for 5% cross-linking. The irradiation of an ATFMD-containing duplex, a substrate of the HIV-1 integrase, in the presence of this enzyme resulted in the covalent DNA-protein complex. The oligonucleotides with the 1-(4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzamido)-2,3-propanediol moiety in their chains can be used for the photoaffinity modification of both nucleic acids and proteins that recognize them. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 4; see also http://www.maik.ru.