[Bacteria that degrade low-molecular linear epsilon-caprolactam olygomers].

Five bacterial strains with the unique ability to utilize low-molecular linear caprolactam olygomers (nylon olygomers) were isolated from soil samples contaminated with industrial wastes of epsilon-caprolactam. Based on the properties studied and also on the analysis of 16S rRNA gene nucleotide sequences, the strains BS2,BS3, BS9, BS38, and BS57 were classified to the general Arthrobacter, Brevibacterium, Microbacteriun, Gulosibacter, and Achromobacter, respectively. All of the strains also utilized 6-aminohexanoic and adipic acids, which are intermidiates of the epsilon-caprolactam catabolism. This indirectly points to the fact that degradation of olygomers in these bacteria occurs via the monomer degradation pathway. The BS9 and BS57 strains utilized only olygomers of the epsilon-caprolactam, while BS2, BS3, and BS38 also degraded epsilon-caprolactam and its homologs, enantolactam and caprylolactam, which differentiates the latter from the previously known degraders of olygomers and suggests the presence in these strains of enzymes with lactam hydrolase activity, in addition to 6-aminohexanoate-dimer hydrolase.

[Investigation of active center of deoxynucleoside monophosphate kinase of bacteriophage T5 by site-directed mutagenesis].

Based on the computer model of active center of bacteriophage T5 deoxyribonucleoside monophosphate kinase amino acid residues essential for the enzyme activity were determined. As the result of site-directed mutagenesis, cloning and expression of the gene in E. coli series of proteins were obtained with single amino acid substitutions of conservative active center residues--S13A, D16N, T17N, T17S, R130K, K131E, Q134A, G137A, T138A, W150F, W150A, D170N, R172I, E176Q. Electrophoretically homogeneous preparations of mutant forms were purified using ion exchange and affinity chromatographic steps. Measuring of the specific enzyme activities of these enzymes for the natural acceptors of phosphoryl group (dAMP, dCMP, dGMP, dTMP) revealed that substitutions of charged residues of NMP-binding domain-namely, R130, R172, D170 and E176-lead to almost complete loss of enzyme activity. It was shown that presence of OH-group at position 17 is also important for catalytic activity. Based on the changes in specific activities we suppose that arginine residues at positions 130 and 172 participate in binding of γ-phosphoryl of donor and α-phosphoryl of acceptor. Also, aspartic acid at 16 position of ATP-binding site (P-loop) probably assists in the binding of acceptor, first of all dTMP. Unequal decrease in enzyme activities for different substrates of partially active mutants--G137A, T138A, T17N, Q134A, S13A, D16N--indicate that in the binding of various substrates different amino acid residues take part.

[Enzymatic transglycosylation of natural and modified nucleosides by immobilized thermostable nucleoside phosphorylases from Geobacillus stearothermophilus].

Natural and modified purine nucleosides have been synthesized using the recombinant thermostable enzymes purine nucleoside phosphorylase II (EC 2.4.2.1) and pyrimidine nucleoside phosphorylase (EC 2.4.2.2) from Geobacillus stearothermophilus B-2194. The enzymes were produced in recombinant E. coli strains and covalently immobilized on aminopropylsilochrom AP-CPG-170 after heating the cell lysates and the removal of coagulated thermolabile proteins. The resulting preparations of thermostable nucleoside phosphorylases retained a high activity after 20 reuses in nucleoside transglycosylation reactions at 70-75 degrees C with a yield of the target products as high as 96%. Owing to the high catalytic activity, thermal stability, the ease of application, and the possibility of repeated use, the immobilized preparations of thermostable nucleoside phosphorylases are suitable for the production of pharmacologically important natural and modified nucleosides.

[Substrate specificity of T5 bacteriophage deoxyribonucleoside monophosphate kinase and its application for the synthesis of [alpha-(32)P]d/rNTP].

Bacteriophage T5 deoxynucleoside monophosphate kinase (dNMP kinase, EC 2.7.4.13) is shown to catalyze the phosphorylation of both d(2)CMP and ribonucleotides AMP, GMP, and CMP, but does not phosphorylate UMP. For natural acceptors of the phosphoryl group, K(m) and k(cat) were found. The applicability of T5 dNMP kinase as a universal enzyme capable of the phosphorylation of labelled r/dNMP was shown for the synthesis of [alpha-(32)P]rNTP and [alpha-(32)P]dNTP.

[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.

[Biotechnological synthesis of ribavirin. Effect of ribavirin and its various combinations on the reproduction of Vaccinia virus]. / Biotekhnologicheskii sposob polucheniia ribavirina. Deistvie ribavirina i nekotorykh ego kombinatsii na reproduktsiiu virusa ospovaktsiny (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.

[Synthesis and antibacterial activity of analogues of the N-terminal fragment of the sarcotoxin IA antimicrobial peptide]. / Sintez i antibakterial'naia aktivnost' analogov N-kontsevogo fragmenta antimikrobnogo peptida sarkotoksina IA.

Three 18-membered analogues of the N-terminal fragment of the sarcotoxin IA cationic antimicrobial peptide were synthesized by the solid phase method of peptide synthesis with the use of swellographic monitoring. The ability of these peptides to inhibit the growth of various bacteria in culture medium and their hemolytic activity in experiments on human erythrocytes were studied. The analogue completely corresponding to the N-terminal amino acid sequence of the natural sarcotoxin IA with the amide group on its C-terminus exhibited higher antibacterial activity. The presence of carboxyl group on the C-terminus or the substitution of Tyr for Trp2 resulted in a decrease in the antimicrobial activity of the peptide. Our results indicate that the amphiphilic N-terminal peptide corresponding to the 1-18 sequence of sarcotoxin IA involves the moieties responsible for the antimicrobial activity of the antibiotic.