Synthesis of conjugates of 2′,3′-dideoxynucleoside-5′-monophosphates with α-amino acids

Previously undescribed conjugates of 2′,3′-dideoxyuridine-5′-monophosphate-(L)-methoxytryptophylphosphoramidate (5) and 2′,3′-dideoxycytidine-5′-monophosphate-(L)-methoxytryptophylphosphoramidate (7) were isolated by a chemical enzymatic method in order to study their pharmacological properties and to prepare new medicinal preparations based on them. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–175, March–April, 2006.     

Effects of the thermal history and concentration on the aggregation of Erwinia gum in an aqueous solution

The aggregation of Erwinia (E) gum in a 0.2 M NaCl aqueous solution was investigated by multi‐angle laser light scattering and gel permeation chromatography (GPC) combined with light scattering. The GPC chromatograms of five fractions contained two peaks; the fractions had the same elution volume but different peak areas, suggesting that aggregates and single chains coexisted in the solution at 25 °C. The apparent weight‐average molecular weights (M_w) of the aggregates and single chains for each fraction were all about 2.1 × 10⁶ and 7.8 × 10⁴, respectively. This indicates that the aggregates were composed of about 27 molecules of E gum in the concentration range used (1.0 × 10⁻⁶ to 5.0 × 10⁻⁴ g/mL). The weight fraction of the aggregates (w_ag) increased with increasing concentration, but the aggregates still existed even in an extremely dilute solution. The fractionation process and polymer concentration hardly affected the apparent aggregation number but significantly changed w_ag. The E‐gum M_w decreased sharply with an increase in temperature. When the E‐gum solution was kept at 100 °C, w_ag decreased sharply for 20 h and leveled off after 100 h. Once the aggregates were decomposed at a higher temperature, no aggregation was observed in the solution at 25 °C, indicating that the aggregation was irreversible. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1352–1358, 2000     

RHEOLOGICAL BEHAVIOR OF ERWINIA GUM IN AQUEOUS SOLUTION*

Erwinia (E) gum, an extracellular polysaccharide, is composed of fucose, galatose, glucose andglucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and arotational viscometer. Its weight-average molecular weight M_w and intrinsic viscosity [η] in 0.2 mol/L NaClaqueous solution were measured by light scattering method at 35℃and viscometry at 25℃and found to be1.06×10~6 g/mol and 1050 mL/g, respectively, and its aggregates in aqueous solution were proved by gelpermeation chromatography (GPC). These results indicated that E gum in water has exceedingly highviscosity and exhibits Binham fluid behavior, owing to its aggregation. The viscosity of E gum decreasedwith increasing temperature, and the turning point appeared at 38℃for dilute solution and 80℃forconcentrated solution suggesting that the aggregates of E gum in water started to disaggregate under thesetemperatures. In addition, the aggregates can be disrupted by adding either acid or base. The experimentalresults indicated that the E gum is a good thickening agent, and its fluid behavior is similar to xanthan.     

苏云金芽胞杆菌AiiA蛋白对魔芋软腐病菌的抗病活性

AiiA蛋白通过破坏病原菌的信号分子来阻断病原菌的群体感应调节系统,达到抗病的目的,是一种新型的抗病蛋白.根据蜡状芽胞杆菌ATCC14579基因组中aiiA序列设计引物,从苏云金芽胞杆菌中成功扩增出aiiA基因,其ORF为753bp,测序后经blast检测与已发表的序列相似性均在95%以上.将此基因克隆到pET28a表达载体中,转化大肠杆菌BL21(DE3),经IPTG诱导,超量表达的蛋白在菌体中以包涵体形式存在,纯化的AiiA蛋白经SDS PAGE电泳检测,表达产物分子量为28×103,致病性测定表明该蛋白对魔芋软腐病菌CZY具有较强的抗病活性.     

Chemical composition and antimicrobial activity of essential oils from Acantholippia deserticola,Artemisia proceriformis,Achillea micrantha and Libanotis buchtormensis against phytopathogenic bacteria and fungi

Essential oils from aerial parts of Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis were analysed by GC–MS. The major compounds identified were β-thujone (66.5 ± 0.2%), and trans-sabinyl acetate (12.1 ± 0.2%) in A. deserticola; α-thujone (66.9 ± 0.4%) in A. proceriformis; 1,8-cineole (26.9 ± 0.5%), and camphor (17.7 ± 0.3%) in A. micrantha and cis-β-ocimene (23.3 ± 0.3%), and trans-β-ocimene (18.4 ± 0.2%) in L. buchtormensis. The oils showed a weak antimicrobial effect (MIC₁₀₀ > 1.5 mg/ml) on most phytopathogens tested. A moderate antimicrobial activity (MIC₁₀₀ between 0.5 and 1.5 mg/ml) was displayed by the oils of A. deserticola, A. micrantha and L. buchtormensis on Septoria tritici and by the oil of A. deserticola on Septoria glycine. The antimicrobial activity was associated to the contents of β-thujone, trans-sabinyl acetate and trans-sabinol. Our results indicate that the tested essential oils have little inhibitory potency not suitable for use as plant protection products against the phytopathogens assayed.     

Structure of the O-polysaccharide of <Emphasis Type="Italic">Erwinia carotovora</Emphasis> ssp. <Emphasis Type="Italic">atroseptica</Emphasis> GSPB 9205 containing a new higher branched monosaccharide

An O-polysaccharide was prepared by mild acid hydrolysis of a lipopolysaccharide of Erwinia carotovora ssp. atroseptica GSPB 9205 and was found to contain a new higher branched monosaccharide, viz., 3,6,8-trideoxy-4-C-(R-1-hydroxyethyl)-D-gulo-octose, which we called erwiniose. The structure of the pentasaccharide repeating unit of the O-polysaccharide was established by monosaccharide analysis, including the determination of absolute configurations, methylation analysis, O-deacetylation, Smith degradation, and one- and two-dimensional NMR spectroscopy. The configuration of erwiniose was determined based on the coupling constants of vicinal protons combined with the nuclear Overhauser effect data and the results of periodate oxidation of the polysaccharide followed by reduction of the resultant 4-keto sugar (the C(1)-C(4)-C(1′)-C(2′) fragment) to give 3,6-dideoxy-D-ribo-hexose(paratose) and oxidation of 3-hydroxybutyraldehyde (the C(5)-C(8) fragment) to give R-3-hydroxybutyric acid. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1239–1244, May, 2005.     

Facile isolation ofEndo-pectate lyase fromErwinia carotovora based on electrostatic interaction

Endo-pectate lyase (PATE) from Erwinia carotovora was selectively cosedimented with extracellularly produced lipopolysaccharide-lipid complex (LPSLC) through dialysis of the cell free culture broth. The selective isolation of PATE was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The cosedimentation of the PATE with LPSLC was initiated by decreasing conductivity of the solution and terminated at approx 1 m siemens (mScm-1). As much as 62% of PATE activity in the culture broth was removed by precipitation. PATE was isolated from the precipitate by gel chromatography. The cosedimentation of PATE with LPSLC was remarkably affected by pH or ionic strength. The addition of polycationic peptide polymyxin B sulfate or a metal chloride affected the interaction. The cosedimentation was diminished by acetylation of the free amino groups of PATE. From these results, it was confirmed that the cosedimentation was induced by electrostatic interaction.