Byproduct with altered fluorescent properties is formed during standard deprotection step of hexachlorofluorescein labeled oligonucleotides.

HEX-labeled oligonucleotides obtained via typical synthetic protocols may contain more than 15% of material with altered spectral characteristics. We discovered hexachlorofluorescein residue transformation unknown earlier for standard DNA ammonolysis step. HEX residue reacts with ammonium hydroxide yielding acridine derivative, which has differed UV-VIS and fluorescent properties compared to HEX. Therefore, for critical bioassays where sensitivity and/or fluorescent signal differentiation (e.g., in quantitative or multiplexed assays) are essential, the careful RP-HPLC purification step is required.

Significance of methods for purification of oligodeoxyribonucleotide probes for the efficiency of gene diagnosis by real-time PCR.

Analysis of the use of real-time PCR with fluorescent registration of results for gene diagnosis of infectious diseases showed that the sensitivity and reliability of quantitative evaluation of DNA targets directly depended on the method of purification of oligonucleotide probes. Chromatographic behavior of synthetic probes carrying various fluorophores and fluorescence quenchers was analyzed. Approaches to optimization of purification methods are proposed enabling elimination of previously undetectable admixtures. The importance of these studies is explained by the need in extending the armory of methods for the development and production of diagnosticums for detection of infectious and hereditary diseases, identification of genetically modified organisms, and for a wide spectrum of research in molecular biology and medicine.

[Telomeric oligonucleotide complexes with PGEk protein vector: internalization by target cells and antiproliferative properties].

The recombinant protein PGEk, containing residual of the human epidermal factor (hEGF) bearing DNA binding sequence, retains ability of hEGF to bind with hEGF receptor and to induce cell proliferation was shown. On an example of PGEk complexes with telomeric mimic-oligodeoxyribonucleotide d(TTAGGG)4 and with its thio-analogue we had found such systems can be effectively and selectively internalized by hEGF receptors super expressing cells. The association of this process with a protein/oligonucleotide ratio in complexes was investigated. The intracellular localization of oligonucleotides was explored. We had shown that PGEk not only promotes intensive delivery of oligonucleotides, but also protects them from degradation by nucleases. The oligonucleotides in composition of complexes have considerably more expressed cytotoxic activity in comparison with free oligonucleotides.

Principles of creation of protein carriers of DNA new derivatives of human epidermal growth factor for gene therapy.

We formulated a new approach to the creation of transport proteins for the delivery of foreign DNA to target cells and used it for obtaining a polypeptide PGEk. Structural and functional analysis of PGEk--DNA complexes demonstrated good prospects for the creation of a wide spectrum of targeted preparations for gene therapy. These approaches and regularities are necessary for construction of new DNA carriers selective for various cell types.

[Complexes of telomeric oligonucleotide d(TTAGGG)4 with the new recombinant protein PGEk--nucleic acid carrier into proliferating cells].

The complexation of the new protein vector PGEk--a carrier of nucleic acids into proliferating cells with phosphodiester d(TTAGGG)4 (TMO) and phosphorothioate Sd(TTAGGG)4 (TMS) telomerase inhibitor oligonucleotides was studied. PGEk molecule, consisting of 64 amino acids, is comprising the sequence of the human epidermal growth factor EGFh which is hydrophobic cell targeting moiety serving for receptor-mediated endocytosis and an NLS (nuclear localization signal) which is hydrophilic serving as a DNA-binding and selective nuclear import moiety. Experiments were carried out in 0.01 M Na-phosphate buffer contained 0.1 M NaCl, pH 7.8 at 37 degrees C. CD spectral analysis revealed that TMO molecules folded back into intramolecular antiparallel G-quadruplex while TMS molecules were represented as unstructured thread. The number of adsorbed PGEk molecules were estimated using PGEk intrinsic fluorescence decrease and fluorescence polarization increase of PGEk under oligonucleotide titration. Adsorption isotherms were plotted in Scatchard coordinates. We have shown that adsorption of the first two PGEk molecules on TMO and TMS occurs noncooperatively with the high association constants K1(TMO) = (7 +/- 1) x 10(7) M(-1) and K1(TMS) = (3 +/- 0.5) x 10(7) M(-1), respectively. Further adsorption up to 5-6 PGEk molecules on TMO occurrs cooperatively with still high association constant K2(TMO) = (4.0 +/- 1.5) x 10(6) M(-1). TMS oligonucleotide binds the third PGEk molecule rather weakly, K2(TMS) = (8 +/- 2) x 10(5) M(-1). CD spectral analysis revealed that G-quadruplex structure formed by TMO have undergone a partial unfolding by binding of PGEk molecules while single-stranded structure formed by TMS was not affected by binding PGEk. Thus, the tertiary structure of DNA and the number of adsorbed PGEk molecules formed biologically active compounds PGEk: TMO and PGEk: TMS were defined, which are able to penetrate through the membrane of proliferating cells and to suppress their growth.

[Synthesis of phosphono analogs of a phospholipid platelet activating factor]. / Sintez fosfonoanalogov fosfolipidnogo faktora aktivatsii trombotsitov.

Structural analogues of phospholipidic platelet activating factor, (2-acetoxy-3-octadecyloxy)propyl-1-phosphonocholine and (2-methoxy-3-octadecyloxy)propyl-1-phosphonocholine, were synthesized. High efficiency of the polymer-bound dibenzo-18-crown-6-ether as the O-alkylation catalyst was demonstrated. Reaction of allyl-octadecyl ether with methanol and iodine in the presence of zinc oxide was shown to give a mixture of 1-iodo-2-methoxy- and 1-methoxy-2-iodoprop-3-yl ethers of octadecanol in the 3:1 ratio.

[Allosteric regulators of reversible oxygenation of hemoglobin]. / Allostericheskie reguliatory obratimoi oksigenatsii gemoglobina.

Properties of regulators of reversible haemoglobin oxygenation, especially of a natural regulator, 2,3-diphosphoglyceric acid (DPG), are reviewed. DPG provides effective deoxygenation of haemoglobin, helps to maintain its functional properties preventing its transformation into inactive derivatives. Correlation between organism metabolic requirements and haemoglobin oxygen affinity is established by erythrocyte DPG. Several functional analogues of DPG, their structure--activity relationship and possible medical application are discussed.

[Synthesis and analysis of glycol bis-phosphates, regulators of reversible hemoglobin oxygenation]. / Sintez i isledovanie bisfosfatov glikolei, reguliatorov obratimoi oksigenatsii gemoglobina.

Bisphosphates of glycols, ethyleneglycol and 1,2-propanediol, were synthesized. These structural analogues of 2,3-diphosphoglyceric acid were shown to reduce significantly the oxygen affinity of stripped hemoglobin.