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1.
Mieczyslaw Remin 《Journal of biomolecular structure & dynamics》2013,31(2):367-382
Abstract The solution distribution of combinations of the sugar ring puckering domains, C2′endo(S), C3′endo(N), and C4′-C5′ rotamers, +sc(g+), ap(t), -sc(g?), in α and β-anomers in ribo- and deoxyribo- pyrimidine nucleic acid components can be determined from vicinal coupling constants (M. Remin, J. Biomol. Str. Dyn. 2, 211 (1984). A general correlation pattern with a conformational constant λ, reflecting an intrinsic physical property of the sugar - side chain ensemble, is developed and expressed in terms of four principles: I) The +sc rotamer contributes to the C3′endo population to a higher extent (1 - Yt) than to C2′endo,(l-Yt-Yg-/Xs). II) The ap rotamer contributes to both C2′endo and C3′endo populations to the same extent (Yt). III) The—sc rotamer contributes only to the C2′endo population, (Yg-/Xs). IV) The molar fractions Xs, Yt and Yg- of conformations C2′endo, ap and—sc, respectively, are strongly correlated, λ = (Yg-/Xs)/Yt ≈ 0.5, and therefore Yt is a basic variable parameter which determines all others in the correlation pattern. In α-anomers, regardless of the type and conformation of the sugar ring and base, the molar fraction Yt = 0.37 ± 0.02. This finding means that different α-anomers show one correlation pattern free of the influence of the base. In β-anomers, structure and conformation of the base are important factors which modulate (through Yt) the correlation pattern, conserving its fundamental features. Yt is considerably increased by a syn-oriented pyrimidine base, but decreases when the base is anti. The transition from anti to syn orientation of the base is followed by destabilization of (C2′endo, +sc) in favor of (C3′endo, ap). The principles of conformational correlations rationalize a variety of correlations observed in the past. 相似文献
2.
Recognition and binding of anions in water is difficult due to the ability of water molecules to form strong hydrogen bonds and to solvate the anions. The complexation of two different carboxylates with 1-(4-carbomethoxypyrrolidone)-terminated PAMAM dendrimers was studied in aqueous solution using NMR and ITC binding models. Sodium 2-naphthoate and sodium 3-hydroxy-2-naphthoate were chosen as carboxylate model compounds, since they carry structural similarities to many non-steroidal anti-inflammatory drugs and they possess only a limited number of functional groups, making them ideal to study the carboxylate-dendrimer interaction selectively. The binding stoichiometry for 3-hydroxy-2-naphthoate was found to be two strongly bound guest molecules per dendrimer and an additional 40 molecules with weak binding affinity. The NOESY NMR showed a clear binding correlation of sodium 3-hydroxy-2-naphthoate with the lyophilic dendrimer core, possibly with the two high affinity guest molecules. In comparison, sodium 2-naphthoate showed a weaker binding strength and had a stoichiometry of two guests per dendrimer with no additional weakly bound guests. This stronger dendrimer interaction with sodium 3-hydroxy-2-naphthoate is possibly a result of the additional interactions of the dendrimer with the extra hydroxyl group and an internal stabilization of the negative charge due to the hydroxyl group. These findings illustrate the potential of the G4 1-(4-carbomethoxy) pyrrolidone dendrimer to complex carboxylate guests in water and act as a possible carrier of such molecules. 相似文献
3.
Hiroaki Terato Hajime Morita Yoshihiko Ohyama Hiroshi Ide 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):131-141
Abstract Reactivities of 5-formyl-2′-deoxyuridine (fdU) and its 5′-monophosphate (fdUMP) to amino acids, amines and thiol compounds in neutral aqueous solution have been studied to elucidate the postmodification of the 5-formyluracil (fU) moiety in cells. fdU and fdUMP specifically reacted with cysteine and its analogs to form thiazolidine derivatives. The reaction involved condensation of the formyl group of fU with both α-NH2 (or NH2 at the equevalent position) and SH groups of cysteine derivatives. 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(10):1671-1672
Multiple alignments of primary structures of many kinds of prenyltransferases that participate in the most fundamental prenyl-chain backbone synthesizing process in isoprenoid biosynthesis showed seven conserved regions in the primary structures of (E)-prenyl diphosphate synthases. However, no information has been available about the structures of (Z)-prenyl diphosphate synthases until our recent isolation of the gene for the undecaprenyl diphosphate synthase of Micrococcus luteus B-P 26.The amino acid sequence of the (Z)-prenyl diphosphate synthase is totally different from those of (E)-prenyl chain elongating enzymes. Protein data base searches for sequences similar to that of the undecaprenyl diphosphate synthase yielded many unknown proteins which have not yet been characterized. Two of the proteins have recently been identified as the undecaprenyl diphosphate synthase of Escherichia coli and the dehydrodolichyl diphosphate synthase of Saccharomyces cerevisiae, indicating that there are three highly conserved regions in the primary structure of (Z)-prenyl chain elongating enzymes. 相似文献
6.
Greice S. Borghetti Ivana S. Lula Ruben D. Sinisterra Valquiria L. Bassani 《AAPS PharmSciTech》2009,10(1):235-242
The present study was designed to investigate the influence of operating conditions (temperature, stirring time, and excess
amount of quercetin) on the complexation of quercetin with β-cyclodextrin using a 23 factorial design. The highest aqueous solubility of quercetin was reached under the conditions 37°C/24 h/6 mM of quercetin.
The stoichiometric ratio (1:1) and the apparent stability constant (Ks = 230 M−1) of the quercetin/β-cyclodextrin complex were determined using phase-solubility diagrams. The semi-industrial production
of a 1:1 quercetin/β-cyclodextrin solid complex was carried out in aqueous solution followed by spray-drying. Although the
yield of the spray-drying process was adequate (77%), the solid complex presented low concentration of quercetin (0.14%, w/w) and, thus, low complexation efficiency. The enhancement of aqueous solubility of quercetin using this method was limited
to 4.6-fold in the presence of 15 mM of β-cyclodextrin. Subsequently, an inclusion complex was prepared via physical mixture
of quercetin with β-cyclodextrin (molar ratio of 1:1 and quercetin concentration of 23% (w/w)) and characterized using infrared spectroscopy, differential scanning calorimetry, nuclear magnetic resonance spectroscopy,
and scanning electron microscopy analyses. The enhancement of aqueous solubility of quercetin using this method was 2.2-fold,
similar to that found in the complex prepared in aqueous solution before the spray-drying process (2.5-fold at a molar ratio
of 1:1, i.e., 6 mM of quercetin and 6 mM of β-cyclodextrin). 相似文献
7.
Koji Tateishi Shinya Hayashi Masahiro Kurosaka 《Biochemical and biophysical research communications》2009,389(4):593-847
In order to analyze the function of DcR3 for the regulation of cell adhesion and apoptosis in macrophages, we investigated the expression of decoy receptor 3 (DcR3) in THP-1 monocytes/macrophages.DcR3 was expressed in THP-1 and increased by phorbol 12-myristate 13-acetate (PMA). The formation of macrophage aggregates was observed when THP-1 cells were differentiated by PMA or stimulated with DcR3-Fc. Undifferentiated THP-1 cells were also induced to form aggregates by DcR3-Fc. The expression of integrin α4 was significantly increased by DcR3-Fc. CHX-induced apoptosis in THP-1 was inhibited by DcR3-Fc, of which inhibition against CHX-induced apoptosis and aggregate formation were ameliorated by anti-VLA4 antibody.DcR3 may play a significant role in macrophages not only by a decoy receptor but also by increasing α4 integrin. 相似文献
8.
Tadao Kurata Masao Fujimaki Yosito Sakurai 《Bioscience, biotechnology, and biochemistry》2013,77(6):1471-1477
At the initial stage of the browning reaction of dehydro-l-ascorbic acid (DHA) with α-amino acid, a kind of red pigment was produced. The pigment was isolated as very hygroscopic red powder from non-aqueous reaction system, and its characterization was made. It was revealed that it had the same structure with that of the red pigment produced by the oxidation of l-scorbamic acid, an intermediate amino-reductone expected to be produced by Strecker degradation. Formation mechanism of the pigment which was considered to be an intermediate of browning reaction of DHA with α-amino acid was also discussed. 相似文献
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Nguyen Van Chuyen Tadao Kurata Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):2209-2210
Enrichment cultures in a medium containing 0.1% methanol and 0.1% bicarbonate at pH 7.0 under anaerobic conditions in the light became mainly green in color. Forty-four enrichment cultures, which showed abundant growth, were obtained from 46 different sources and found to contain cells of methanol-utilizing bacteria and green algae as predominant members. From these enrichment cultures, two strains of bacteria and two strains of algae were isolated. The microorganisms isolated were designated as bacterium No. 7, bacterium No. 8, Chlorella sp. A-1 and Chlorella sp. B-1, respectively. Stable mixed cultures were easily formed by mixing the isolated cultures of bacteria and algae. Both methanol and bicarbonate were necessary for the growth of the mixed cultures under anaerobic-light conditions. Growth behavior of the mixed cultures was examined on a medium containing 0.1% methanol and 0.1 % bicarbonate at 30°C in the light (about 6000 lx). The maximum specific growth rate for the cultures, µmax, was 0.092 hr?1 (doubling time, 7.5 hr). The maximum cell yield was 0.87 g dry-cell weight per g of methanol used. The protein content of the biomass was 65%. 相似文献
12.
Anders Viks?-Nielsen Andreas Blennow Tom Hamborg Nielsen Birger Lindberg M?ller 《Plant physiology》1998,117(3):869-875
The possible involvement of potato (Solanum tuberosum L.) starch-branching enzyme I (PSBE-I) in the in vivo synthesis of phosphorylated amylopectin was investigated in in vitro experiments with isolated PSBE-I using 33P-labeled phosphorylated and 3H end-labeled nonphosphorylated α(1→4)glucans as the substrates. From these radiolabeled substrates PSBE-I was shown to catalyze the formation of dual-labeled (3H/33P) phosphorylated branched polysaccharides with an average degree of polymerization of 80 to 85. The relatively high molecular mass indicated that the product was the result of multiple chain-transfer reactions. The presence of α(1→6) branch points was documented by isoamylase treatment and anion-exchange chromatography. Although the initial steps of the in vivo mechanism responsible for phosphorylation of potato starch remains elusive, the present study demonstrates that the enzyme machinery available in potato has the ability to incorporate phosphorylated α(1→4)glucans into neutral polysaccharides in an interchain catalytic reaction. Potato mini tubers synthesized phosphorylated starch from exogenously supplied 33PO43− and [U-14C]Glc at rates 4 times higher than those previously obtained using tubers from fully grown potato plants. This system was more reproducible compared with soil-grown tubers and was therefore used for preparation of 33P-labeled phosphorylated α(1→4)glucan chains. 相似文献
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J. Tomasz 《Nucleosides, nucleotides & nucleic acids》2013,32(1):63-79
Abstract The title compound 1 is prepared from thymidine 5′-phos-phorodiamidate (2) and inorganic pyrophosphate (3) in anhydrous DMF, at 30–32°C. The products of alkaline hydrolysis of 1, at room temperature, are: thymidine 5′-phosphoramidate (4), thymidine 3′-phosphoramidate (8) and thymidine (9) as well as 3 and inorganic trimetaphosphate (10). In 1 N NH4OH, 1 reacts with cytidine (15) to form cytidylyl-/2T(3′)-5′/-thymidine (16) and a mixture of cytidine 2′,3′-cyclic phosphate (17) and 9. 相似文献
15.
Hirofumi Nakano Sumio Kitahata Haruko Kinugasa Yasuto Watanabe Hiroshi Fujimoto Katsumi Ajisaka 《Bioscience, biotechnology, and biochemistry》2013,77(8):2075-2082
A transfer reaction catalyzed by an exo-β-1,4-galactanase from Bacillus subtilis was studied. The enzyme had a broad acceptor specificity and transferred galactobiosyl residues to acceptors such as various alcohols, including hydroxy benzenes and saccharides. Transfer products of glycerol formed by the enzyme were compared with those formed by Escherichia coli β-galactosidase and by Penicillium citrinum endo-galactanase. E. coli enzyme transferred 90% of galactose residues to the primary hydroxyl groups of glycerol and P. citrinum endo-enzyme transferred 80% of saccharide residues to the secondary hydroxyl group. The B. subtilis exo-galactanase was less specific than the other two enzymes and formed two products (1-DG and 2-DG) with a 2-DG/l-DG ratio of about 2. The structures of the saccharides were examined by 13C-nuclear magnetic resonance analysis and by enzymatic hydrolysis. 1-DG and 2-DG were elucidated to be O-β-d-galactosyl-(l→4)-O-β-d-galactosyl-(1→1)-glycerol and O-β-d-galactosyl-(l→4)-O-β-d-galactosyl-(l→2)-glycerol, respectively. The efficiency of the transfer reaction was measured at various concentrations of glycerol using galactotriose as a donor. About 40–75% of galactobiosyl residues were transferred at an acceptor concentration range of 20–100 mg/ml. 相似文献
16.
Summary Activity of amylopullulanase from Thermoanaerobacter ethanolicus 39E on -1,6 and -1,4-glucosidic linkages in highly branched mammalian glycogen was analyzed by paper chromatography and 13C nuclear magnetic resonance (NMR) spectroscopy. Paper chromatography analysis showed that the glycogen hydrolysate consisted of glucose, maltose, maltotriose and maltotetraose. NMR spectroscopy confirmed that no hydrolysate products of -1,6 linkage were present resulting from treatment with the amylopullulanase. Therefore, the amylopullulanase efficiently hydrolyzed glycogen both at -1,6- and at -1,4-glucosidic linkages into oligosaccharides. 相似文献
17.
Ashima Kapoor H. R. Singal Sunita Jain 《Journal of plant biochemistry and biotechnology.》2003,12(2):157-158
Infection of Brassica juncea plants with Albugo candida caused the induction of β-1,3-glucanase in the leaf tissues following inoculation; the induction being more pronounced in the resistant cultivars. The enzyme purified from infected leaves of resistant cultivar RC-781 had a molecular mass of 35.4 kD. The enzyme exhibited its optimum activity at 50°C and at pH 5.5 with Km value of 0.55 mg laminarin ml?1. The enzyme activity was slightly stimulated by Cl? and Mg++, while inhibited by Hg++ and Mn++ at higher concentrations only 相似文献
18.
《Bioscience, biotechnology, and biochemistry》2013,77(10):2172-2178
Four fractions of a water-insoluble α-(1→3)-D-glucan GL extracted from fruiting bodies of Ganoderma lucidum were dissolved in 0.25 M LiCl/DMSO, and then reacted with sulfur trioxide-pyridine complex at 80°C to synthesize a series of water-soluble sulfated derivatives S-GL. The degree of substitution of DS was measured by using IR infrared spectra, elemental analysis, and 13C NMR to be 1.2-1.6 in the non-selective sulfation. Weight-average molecular weight Mw and intrinsic viscosity [η] of the sulfated derivatives S-GL were measured by multi-angle laser light scattering and viscometry. The Mw value (2.4×104) of sulfated glucan S-GL-1 was much lower than that (44.5×104) of original α-(1→3)-D-glucan GL-1. The Mark-Houwink equation and average value of characteristic ratio C∞ for the S-GL in 0.2 M NaCl aqueous solution at 25°C were found to be: [η]=1.32×10-3Mw1.06 (cm3 g-1) and 16, respectively, in the Mw range from 1.1×104 to 2.4×104. It indicated that the sulfated derivatives of the α-(1→3)-D-glucan in the aqueous solution behave as an expanded chain, owing to intramolecular hydrogen bonding or interaction between charge groups. Interestingly, two sulfated derivatives synthesized from the α-(1→3)-D-glucan and curdlan, a β-(1→3)-D-glucan, all had significant higher antitumor activity against Ehrlich ascites carcinoma (EAC) than the originals. The effect of expanded chains of the sulfated glucan in the aqueous solution on the improvement of the antitumor activity could not be negligible. 相似文献
19.
Russell P. Newton 《Nucleosides, nucleotides & nucleic acids》2013,32(6):1009-1018
Abstract uv absorbance spectrophotometry is the routine method of determining nucleotide concentrations in solution. To obviate the need for determining solution pH a method is described whereby cyclic CMP concentration in aqueous solution is calculated from absorbances at four wavelengths: the rationale is of general applicability to nucleosides and nucleotides. 相似文献
20.
Marta Rodríguez-García Núria Climent Harold Oliva Víctor Casanova Rafael Franco Agathe Leon José M. Gatell Felipe García Teresa Gallart 《PloS one》2010,5(2)