[Optimization of the industrial production of the recombinant precursor of human insulin]

Conditions were found at the analytical level for the solubilization of a recombinant insulin precursor from inclusion bodies in different buffer systems at a wide pH range in the presence of different reducing (dithiothreitol, dithioerythritol) and chaotropic agents (urea, guanidine hydrochloride) and the subsequent renaturation with the use of redox pairs (cysteine-cystine, oxidized glutathione-reduced glutathione, and others). The scaling of the method for the production of the active substance of genetically engineered human insulin has been performed.

[The influence of growth medium composition and physicochemical factors on biosurfactant production by the bacterium Bacillus licheniformis VKM B-511]

The ability of Bacillus licheniformis strain VKM B-511 to grow and synthesize biosurfactants under both aerobic and anaerobic conditions has been demonstrated. Yields of biosurfactants, emulsion indices and surface tension were considerably higher in culture liquor and preparations derived from cultures grown anaerobically at a C/N ratio of 1 : 24, pH 7.0, and temperature of 30 degrees C. Biosurfactant production by B. lichenformis also depended on concentrations of NaCl and Na2S in the medium and on water characteristics, reaching 4.58 g/l for bacteria grown anaerobically on a medium containing anolyte fraction of water.

[Expression of human serum albumin in metylotrophic yeast Pichia pastoris and its structural and functional analysis]

The stable strain of methylotrophic yeast Pichia pastoris secreting human serum albumin into cultural medium was obtained. Optimal conditions for expression of the protein were determined. We characterized the recombinant protein by mass spectrometry and circular dichroism and analyzed its catalytic activity.

An enzymatic transglycosylation of purine bases

An enzymatic transglycosylation of purine heterocyclic bases employing readily available natural nucleosides or sugar-modified nucleosides as donors of the pentofuranose fragment and recombinant nucleoside phosphorylases as biocatalysts has been investigated. An efficient enzymatic method is suggested for the synthesis of purine nucleosides containing diverse substituents at the C6 and C2 carbon atoms. The glycosylation of N(6)-benzoyladenine and N(2)-acetylguanine and its O(6)-derivatives is not accompanied by deacylation of bases.

[Synthesis of 2-chloro-2'-deoxyadenosine by microbiological transglycosylation using a recombinant Escherichia coli strain]

Cladribine (2-chloro-2'-deoxyadenosine) was synthesized using intact cells of the recombinant Escherichia coli strain producing Geobacillus stearothermophilus B-2194 thermostable purine-nucleoside phosphorylase II (EC 2.4.2.1). Use of the cells containing this thermostable enzyme allowed the process to be conducted at a temperature of 70 degrees C, which provided the maximal concentrations of sparingly soluble substrates. The best results were obtained with 2-chloroadenine as a modified base. The highest yield of the target 2-chloro-2'-deoxyadenosine (up to 95% in the case of deoxyguanosine) was reached when using 2'-deoxypurines as donors of deoxyribose. Use of thymidine for these purposes required its considerable molar excess over 2-chloroadenine (up to 6 : 1), which is connected with a nonoptimal amount of endogenous thymidine phosphorylase, necessary for synthesis of deoxyribose-1-phosphate, in the transglycosylation reaction.

[Recombinant oxyntomodulin]

An artificial gene encoding oxyntomodulin was obtained using chemical and enzymatic methods and cloned into Escherichia coli. A recombinant plasmid was constructed containing a hybrid oxyntomodulin gene and Ssp dnaB intein from Synechocystis sp. The expression of the resulting hybrid gene in E. coli, its properties, and the conditions of its autocatalytic cleavage to oxyntomodulin were studied.

[Prospects for designing Russian gene engineering agents for medicine. Rastan is the first Russian recombinant human growth hormone]

The development of modern pharmacology cannot be imagined without the use of genetic engineering methods (recombinant DNA technology). The success of medicine is increasingly based on the active use of protein preparations obtained using the technology of transferring hereditary information (genes) from one organism to another. The emergence of the ability to express foreign genes in the cells of various organisms (both eukaryotes and prokaryotes) has become one of the revolutionary events in the science of the last two decades of the 20th century and laid the foundations of modern biotechnology.

Substrate specificity of Escherichia coli thymidine phosphorylase

Substrate specificity of Escherichia coli thymidine phosphorylase to thymidine derivatives modified at 5' -, 3' -, and 2' ,3' - positions of the sugar moiety was studied. Equilibrium and kinetic constants (K(m), K(I), k(cat)) of the phosphorolysis reaction have been determined for 20 thymidine analogs. The results are compared with X-ray and molecular dynamics data. The most important hydrogen bonds in the enzyme-substrate complex are revealed.

[Biological activity of electrochemically activated solutions obtained in a diaphragm electrolyser]

The biological activity of the catholyte and anolyte of bidistilled water in experiments with the germination of wheat grains in the period from March to May has been studied. The activity of solutions, which was characterized by the grain germination index, was high at the beginning of the period, then it gradually decreased and was equal to zero at the middle of the period; at the end of the period it gradually increased almost to initial values. It has been established that the effectiveness of bidistilled water anolyte was as a rule higher than that of catholyte throughout the observation period. At the beginning and end, the stimulating effect of anolyte was 5-5.5 times greater than that of catholyte. The seasonal changes in the biological activity of M 9 medium catholyte were compared with those of bidistilled water anolyte and catholyte. The stimulating effect of M 9 catholyte was estimated by changes in the growth of E. coli cells. The stimulating effect, which was estimated from an increase in the optical density of cell suspension in the initial period at a cultivation temperature of 20 degrees C was 55-60% relative to control (untreated medium). Then it decreased almost to zero in the middle of the period to increase again approximately to the initial values. The assumption has been made that the physicochemical causes of the influence of catholyte and anolyte of bidistilled water on wheat grains and of the culture medium catholyte on E. coli cells are of different nature.

Production and purification of recombinant human glucagon overexpressed as intein fusion protein in Escherichia coli

Chemico-enzymatic synthesis and cloning in Esherichia coli of an artificial gene coding human glucagon was performed. Recombinant plasmid containing hybrid glucagons gene and intein Ssp dnaB from Synechocestis sp. was designed. Expression of the obtained hybrid gene in E. coli, properties of the formed hybrid protein, and conditions of its autocatalytic cleavage leading to glucagon formation were studied.

Ribokinase from E. coli: expression, purification, and substrate specificity

Ribokinase (RK) was expressed in the Escherichia coli ER2566 cells harboring the constructed expression plasmid encompassing the rbsK gene, encoding ribokinase. The recombinant enzyme was purified from sonicated cells by double chromatography to afford a preparation that was ca. 90% pure and had specific activity of 75 micromol/min mg protein. Catalytic activity of RK: (i) is strongly dependent on the presence of monovalent cations (potassium>>>ammonium>cesium), and (ii) is cooperatively enhanced by divalent magnesium and manganese ions. Besides D-ribose and 2-deoxy-D-ribose, RK was found to catalyze the 5-O-phosphorylation of D-arabinose, D-xylose, and D-fructose in the presence of ATP, and potassium and magnesium ions; L-ribose and L-arabinose are not substrates for the recombinant enzyme. A new radiochemical method for monitoring the formation of D-pentofuranose-5-[32P]phosphates in the presence of [gamma-32P]ATP and RK is reported.

[On the fluorescence of bidistilled water after electrochemical treatment]

The short-wave fluorescence of bidistilled water treated in the cathode and anode chambers of two types of electrolysers made from different materials was investigated by fluorescence spectroscopy. It was shown that the electrochemical treatment of water did not induce intrinsic short-wave flyorescence of catholyte and anolyte in the case of quartz glass electrolyser. The increase observed in the intensity of intrinsic short-wavelength fluorescence of bidistilled water in the catholyte and anolyte of the electrolyser made from technical organic glass was caused by microcontaminations released from electrolyser material in the samples.

Galectins as markers of aggressiveness of mouse mammary carcinoma: towards a lectin target therapy of human breast cancer

Galectins, beta-galactoside binding proteins, expressed selectively in human breast carcinoma are attractive targets to employ lectin-aimed therapeutics. We examined beta-galactoside binding potency of neoplastic cells using fluorescein-labelled synthetic glycoconjugates as probes for flow cytometry. As a result, surface beta-galactoside binding proteins/galectins were discovered on mouse mammary carcinoma cells in vitro and in vivo unlike non-malignant cells from the several tissues; and asialo-GM1 ganglioside carbohydrate part--containing probe was the most specific one. However, in liver and lung metastatic cells galectins seem to be expressed within cytoplasm and/or nuclei. Galectin expression correlated directly with aggressive tumour potential in the A/Sn transplantable model similar to findings in several human breast carcinoma cell lines. However, galectin expression was reduced during tumour progression in more aggressive forms of spontaneous BLRB mammary carcinomas like it was shown for human breast carcinoma specimens. Analysis of the histopathological data led, however, to the conclusion that galectin expression hardly might be a suitable marker of aggressiveness of heterogeneous mammary carcinomas as the observed level of galectin expression is influenced by the amount of the stroma in a tumour sample and/or probably, galectin expression inversely correlates with tumour aggressiveness during the initial and advanced steps of mammary tumour progression. We conclude that surface beta-galactoside binding proteins/galectins that are selectively expressed during mouse mammary carcinoma progression, similarly to human breast carcinomas, seem to be proper targets for asialo-GM1-vectored cytotoxics and our mouse model system might be a relevant instrument to further test novel modes of anti-breast cancer therapy.

A PCR-based semiquantitative assay of DNA impurities in recombinant protein preparations

A semiquantitative assay of DNA impurities in preparations of human recombinant insulin is described. The assay is based on the detection of a fragment of the ampicillin-resistant gene within the producer strain DNA by PCR. The analysis of PCR products of the studied preparations and PCR products containing known amounts of E. coli total DNA enabled a quantitative determination of the producer strain DNA content in the preparations under study. The sensitivity of the method is 7 pg of E. coli DNA per 10 microg of human recombinant insulin. The high sensitivity of the method allows us to recommend it for the quantitative determination of DNA content in recombinant preparations that do not inhibit PCR.

Ribavirin: Biotechnological Synthesis and Effect on the Reproduction of Vaccinia Virus

The biotechnological method of synthesis of ribavirin, vidarabin, and 6-azauridine by the use of immobilized recombinant enzymatic preparations of nucleoside phosphorylase was improved. The effect of ribavirin and its combinations with the other synthesized nucleosides on the reproduction of Vaccinia virus was studied using cultures of Vero cells. The combination of ribavirin and vidarabin was shown to provide an antiviral effect at lesser concentrations than when these compounds were taken separately. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.

[Using of 4-thiouridine and 4-thiothymidine for pyrimidine nucleoside phosphorylase studing]

4-Thiouridine and 4-thiothymidine were developed as efficient substrates for spectrophotometric determination of uridine phosphorylase and thymidine phosphorylase activity. 4-Thiouridine has maximum absorbance at 330 nm (pH 7.5). The change in extinction coefficient for 4-thiouridine/4-thiouracil, deltaepsilon is 3000 M(-1) x cm(-1). It appeared that 4-thiouridine is a good substrate for uridine phosphorylase with Michaelis-Menten constant 130 microM and kcat 49 s(-1). In the case of 4-thiothymidine/4-thiothymine deltaepsilon is even larger: 5000 M(-1) x cm(-1) at 336 nm.

[The causes of the biological action of electrochemically activated solutions by changes in the growth of Escherichia coli cells]

To study the causes of the biological effect of electrochemically activated solutions, nutrient growth media M 9 were prepared using catholyte and anolyte solutions containing separate components of the nutrient medium, such as distilled water, phosphate buffer, phosphate buffer with chlorides (NaCl, NH4Cl), and chlorides. The biological activity of different nutrient media was assessed by a comparison with the stimulation or inhibition of the growth of Escherichia coli cells in the catholyte and anolyte of the complete nutrient medium M 9. It was shown that medium M 9 prepared on the catholytes of different initial solutions acquired the stimulating properties only if the initial solution contained salts containing chlorine. The stimulating effect of the initial solution was 18-24%. Electrochemical treatment of solutions containing no chlorides (distilled water, phosphate buffer) and subsequent addition of the components of nutrient medium to exposed solutions had neither a stimulating nor the inhibiting effect on cell growth. The cultivation of cells in a nutrient medium based on the catholyte of preliminarily treated hydrochloric acid showed that it is the presence of chlorine ions in solution during electrolysis that causes the stimulating effect of the nutrient medium based on the catholyte. The formation of oxidizers and the inhibitory effect of the anolyte described previously was also observed if the solution contained chlorine ions during electrolysis. Possible mechanisms of the biological effect of catholytes containing chlorides during electrolysis were discussed.

Recombinant Thymosin 1

An artificial gene encoding thymosin alpha1 was obtained by the chemoenzymatic synthesis and cloned into Escherichia coli. An expressing recombinant plasmid containing the hybrid protein gene, which encodes amino acid sequences of thymosin alpha1 and the Saccharomyces cerevisiae intein Sce VMA, was constructed. The expression of the hybrid protein from the resulting hybrid gene in E. coli, the properties of the resulting hybrid protein, and the conditions for its nonenzymatic cleavage to thymosin alpha1 were studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 5; see also http: // www.maik.ru.

[Level of hydrogen peroxide in electrochemically activated solutions and study of its effect on growth of Escherichia coli]

The formation of hydrogen peroxide in catholytes and anolytes of electrochemically activated solutions: bidistilled water and solutions of sodium chloride and nutrition medium M9 was studied. The concentration of hydrogen peroxide was determined by the method of enhanced chemiluminescence in a system peroxidase-luminol-p-iodophenol. It was shown that the concentration of hydrogen peroxide depends on the ionic content of the solution and varies from a few fractions of a micromole in catholytes of bidistilled water and sodium chloride solutions (10(-5) divided by 10(-2) M) to 20-25 microM in catholytes of medium M9. The concentration of H2O2 in anolytes of various solutions was 15-20 times lower than in the corresponding catholytes and was equal to a few nanomoles in bidistilled water and a few micromoles in medium M9. The biological activity of the catholyte of medium M9 was determined from changes in the growth of E. coli cells. It was found that this catholyte stimulates the cell growth. The stimulating effect was 20-25% and did not change after the decomposition of hydrogen peroxide in the catholyte by catalase. The addition of H2O2 at the corresponding concentration to the inactivated nutrient medium produced no stimulating effect. These data suggest that hydrogen peroxide formed in the catholyte of nutrient medium M9 does not affect its biological activity.

Chemical and Chemoenzymatic Synthesis of Nucleoside 5′-α-Thiotriphosphates

New methods of chemical and chemoenzymatic synthesis of nucleoside 5'-thiophosphates and 5'-alpha-thiotriphosphates are developed. The 5'-alpha-thiotriphosphates are used as substrates both in template-dependent enzymatic PCR synthesis and in a T7-RNA transcription polymerase system. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2003, vol. 29, no. 6; see also http://www.maik.ru.

Production And Purification Of Recombinant Human Oxytocin Overexpressed As A Hybrid Protein In Escherichia Coli

The plasmid DNA pERilox4 containing the gene of the recombinant protein, which included the leader sequence and the oxytocinoyl lysine tetramer, was constructed. The high level of gene expression in E. coli was achieved. The method for purification of the recombinant protein and its isolation in the soluble form was developed. The conditions for digestion of the hybrid protein by trypsin and carboxypeptidase B were matched. The effective method for transformation of oxytocinic acid to oxytocin was worked out. The scheme suggested allowed obtaining oxytocin in high yield.

Therapeutic effect of a single peritumoural dose of IL-2 on transplanted murine breast cancer

Interleukin-2 therapy is not clearly effective against breast cancer both in mouse models and in human patients. However, the study of IL-2 therapy of breast cancer remains important, as 3,700 women died from this malignancy in the Netherlands in 2000. Previously we have shown the therapeutical efficacy of a single peritumoural IL-2 application in different experimental models and in veterinary patients. Here we apply this mode of IL-2 therapy to advanced mouse mammary carcinoma models, i.e., severe metastasised tumours in A/Sn mice and non-metastasised carcinomas in BALB/c mice. Mice with advanced transplanted mammary carcinomas were given a single peritumoural treatment with 2.5 x 10(6) IU IL-2 at days 10-14 after i.p. or s.c. inoculation of 10(6) carcinoma cells. Within each experiment it was always possible to distinguish relatively slowly and fast growing tumours which allows the therapeutical effect of IL-2 in tumours with different growth rates to be studied. A new approach to analyse results enabled us to show that survival of mice with transplanted, advanced metastasised breast cancer can be significantly improved after a single local treatment with IL-2. Advanced relatively fast i.p and s.c. growing mammary carcinomas seem to be more sensitive to a single IL-2 treatment than relatively slowly growing tumours. IL-2 was most effective against non-metastasised mouse breast cancer.

[A new approach to enhance PCR specificity]

A new approach to enhanced specificity and product yield of polymerase chain reaction is proposed. It is based on control of DNA polymerase activity during PCR by changing the magnesium ion concentration, which depends on the temperature of the reaction mixture. A slightly soluble magnesium salt, magnesium oxalate, whose solubility depends on temperature, was used as a source of magnesium ions. During PCR, magnesium oxalate was maintained at saturating concentration by the presence of an insoluble excess of this salt, and the concentration of magnesium ions depended on the salt solubility: binding of magnesium ions at lower temperatures and their release at higher temperatures was shown to affect the DNA polymerase activity and to favor the specific PCR amplification of the target DNA fragment.