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1.
Roots of Arctium tomentosum (Compositae) were found to contain water-soluble polysaccharides (glucofructans), pectinic substances, and hemicellulose. The structure of the glucofructan was established by chemical methods and IR and 13C NMR spectroscopies. 相似文献
2.
T. Sh. Suladze V. Yu. Vachnadze D. M. Tsakadze M. D. Gedevanishvili L. E. Tsutsunava N. A. Malazoniya 《Chemistry of Natural Compounds》2006,42(1):71-74
The alkaloid accumulation dymanics in Veratrum lobelianum were investigated. Jervine was found from 0.02 to 0.11% in the subterranean part at all vegetation stages. The jervine content
was greatest in subterranean plant organs, reaching a maximum (0.3%) during natural dying off of aerial organs. Jervine, a
natural analog of serotonin, can be used as a specific fibroblast growth factor.
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Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 57–59, January–February, 2006. 相似文献
3.
D. N. Olennikov L. M. Tankhaeva G. G. Nikolaeva A. V. Tsyrenzhapov S. M. Nikolaev G. V. Chekhirova 《Chemistry of Natural Compounds》2004,40(1):1-5
Leaves of Cacalia hastate L. (Asteraceae) were composed of free sugars, water-soluble polysaccharides (arabinogalactan type), pectinic substances, hemicelluloses, and cellulose. The hypoglycemic activity was determined for the water-soluble polysaccharides and pectinic substances. 相似文献
4.
A method for determining with a relative uncertainty of less than 3% the total content of polysaccharides in Plantago major leaves that were converted to galacturonic acid was developed using the Dreywood method. The polysaccharide content in Plantago major leaves determined by the developed method was 1.44–1.52%.
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Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 221–223, May–June, 2006 相似文献
5.
Oil pumpkin (Cucurbita pepo L. var. Styriaca) is an economically important horticultural plant cultivated for oil production. After harvesting seeds, the residual biomass
has a limited application and is usually left in the field. An experimental study was performed to evaluate the chemical composition
of the seeded fruit oil pumpkin biomass (OP) dried by solvent-exchange using ethanol. The sugar composition of polysaccharides
obtained by sequential extraction with water and dilute alkali indicated the prevalence of pectic polysaccharides. Hemicelulloses
were released in higher amounts in the alkaline step. The chemical composition of OP and its individual tissues (peel, flesh
and hairy flesh) was investigated and compared to the corresponding preparations of standard pumpkin (SP, Cucurbita pepo L.). The content of components (on oven-dry basis), calculated from the analysis data of the individual tissues, was estimated
for OP: 7.9 % ash, 7.6 % Klason lignin, 19.3 % pectin (as uronic acids), 34.1 % neutral carbohydrates, and 27.4 % α-cellulose
and for SP: 6.4 % ash, 4.0 % Klason lignin, 20.9% pectin (as uronic acids), 38.1% neutral carbohydrates, and 29.2 % α-cellulose,
respectively. The OP biomass showed a higher proportion of hemicelluloses. 相似文献
6.
V. U. Khuzhaev I. Zh. Zhalolov M. G. Levkovich S. F. Aripova A. S. Shashkov 《Russian Chemical Bulletin》2004,53(8):1765-1767
The structure of a new dimeric indole alkaloid, arundarine, isolated from the roots of the plant Arundo donax L. (Poaceae) was determined. On the basis of spectroscopic data, arundarine was identified as 5-[3-(2-dimethylaminoethyl)indol-1-yl]-6-hydroxy-N
2-methyl-1,2,3,4-tetrahydro--carboline.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1697–1699, August, 2004.For Part 14, see Ref. 1. 相似文献
7.
5-Alk(en)ylresorcinols in rye, wheat, spelt, and barley have been characterized by high-performance liquid chromatography
coupled to atmospheric pressure chemical ionization multistage mass spectrometry (HPLC-APcI-MS
n
) for the first time. Among the 29 compounds analysed, several major and minor C15, C17, C19, C21, C23, and C25-substituted resorcinols with saturated, monoenoic, dienoic, and/or oxygenated side-chains were characterized by their specific
fragmentation patterns in collision-induced dissociation experiments. Additionally, a C27:0 homologue, which has probably been overlooked in previous studies based on HPLC alone, was detected in all cereals analysed.
Furthermore, we provide tentative evidence for the occurrence of alkylresorcinols with triolefinic side-chains, which have,
to our knowledge, so far not been reported in any cereal species. 相似文献
8.
Nadtochenko V. A. Khudyakov D. V. Abramova N. V. Vorontsov E. V. Loim N. M. Gostev F. E. Tovbin D. G. Titov A. A. Sarkisov O. M. 《Russian Chemical Bulletin》2002,51(6):986-993
The relaxation of the Q1(—*) excited state of the nonprotonated Fc4PH2 and diprotonated Fc4PH4
2+ forms of meso-tetraferrocenylporphyrin was studied by femtosecond laser absorption spectroscopy. Transition from the Q1(—*) state to the charge-transfer state was shown to occur within 208±10 fs for Fc4PH2 and 9±3 ps for Fc4PH4
2+. A fast vibrational relaxation with a characteristic time of 120—140 fs was found for both forms. The relaxation time of Fc+—P– charge-transfer state for Fc4PH2 was 17±4 ps. 相似文献
9.
Car-Parrinello molecular dynamics (CPMD) simulations have been performed on ubisemiquinone radical anion in aqueous solution.
The different types of hydrogen bonding formed between the semiquinone and the solvent were studied in terms of frequency
and directionality, in comparison with the parent benzosemiquinone radical anion. The EPR parameters (g-tensors and hyperfine coupling constants) were obtained from quantum chemical property calculations performed on snapshots
along the MD trajectory, and the contributions of different solvation effects to the EPR parameters have been evaluated. The
influence of the anion’s conformational behaviour was examined, including the orientation-dependent effects of hyperconjugation
on side-chain hyperfine coupling. 相似文献
10.
Apocytochrome b5 (apocyt b5) with heme removal from the heme-binding core 1, and its mutants with amino acid replaced in the hydrophobic core 2, namely apocyt b5 Y7P, P81A and H15R/S20E, have been subjected to molecular dynamics (MD) simulation at high temperature (500 K) for elucidating their folding behaviors. The early events upon thermal induced unfolding were found to be in good agreement with available experimental results, and the lowest stability of Y7P was predicted among the four apoproteins. The influences of these key residues on protein folding behavior were compared directly at an atomic level. At the same time, the influences of non-native interactions of hydrogen bonds and salt-bridges on protein stabilities were analyzed in detail. The insights from current MD simulations are valuable for understanding the apoprotein folding and the holoprotein formation in terms of heme proteins. 相似文献
11.
V. Živica 《Journal of Thermal Analysis and Calorimetry》1996,46(2):611-617
The objects of the paper are the results of the study on the compatibility of copper refining waste with cement system. The study based on the use of thermal analysis and the comparison of its results with further applied methods (tests of setting, compressive strength and pore analysis) showed good compatibility of the waste up to 20% dose opposite to the cement. It seems that the waste action in cement paste with the Ca(OH)2 binding, produced in the cement process hydration, is connected. 相似文献
12.
MntA from Lactobacillus plantarum and copA from Enterococcus hirae both encode membrane proteins that are members of the P-type family of adenosine triphosphatases (ATPases). Both transporters
act as metal importers to take up nutritionally required substrates; MntA translocates Mn(II) and CopA translocates Cu(I).
Both ATPases can also translocate secondary substrates, Cd(II) and Ag(I), respectively. Although functionally and sequentially
similar, these ATPases differ in several key residues and in their membrane topologies. The bioaccumulation properties of
these two proteins were examined by coexpressing the transporters with overexpressed metallothionein in Escherichia coli cells, a system that has previously shown high levels of substrate-specific uptake. Both strains exhibited rapid metal accumulation,
both saturated at around 50 μM metal, and both displayed temperature-sensitive uptake. However, the transporters responded differently when external conditions
were varied; MntA displayed increased sensitivity to ionic strength, while CopA was more pH sensitive and more inhibited by
chelating agents. The differences in accumulation are likely owing to structural differences in the transmembrane region of
these two ATPases. 相似文献
13.
U. M. Azizov D. B. Mirakilova N. T. Umarova S. A. Salikhov D. A. Rakhimov L. G. Mezhlumyan 《Chemistry of Natural Compounds》2007,43(5):508-511
Dry extracts from roots and stems of Alcea rosea were prepared. Their chemical composition was studied by characterizing the carbohydrate, protein, and elemental compositions.
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Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 417–419, September–October, 2007. 相似文献
14.
Mycobacterium tuberculosis 1-deoxy-d-xylulose-5-phosphate reductoisomerase (MtDXR) is a potential target for antitubercular chemotherapy. In the absence of its crystallographic structure, our aim was
to develop a structural model of MtDXR. This will allow us to gain early insight into the structure and function of the enzyme and its likely binding to ligands
and cofactors and thus, facilitate structure-based inhibitor design. To achieve this goal, initial models of MtDXR were generated using MODELER. The best quality model was refined using a series of minimizations and molecular dynamics
simulations. A protein–ligand complex was also developed from the initial homology model of the target protein by including
information about the known ligand as spatial restraints and optimizing the mutual interactions between the ligand and the
binding site. The final model was evaluated on the basis of its ability to explain several site-directed mutagenesis data.
Furthermore, a comparison of the homology model with the X-ray structure published in the final stages of the project shows
excellent agreement and validates the approach. The knowledge gained from the current study should prove useful in the design
and development of inhibitors as potential novel therapeutic agents against tuberculosis by either de novo drug design or
virtual screening of large chemical databases.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Flavonoids uncharacteristic of intact plants were isolated from callus tissue of Iris ensata and were identified as 5-hydroxy-4′-methoxyflavone, 5-hydroxy-3′-methoxyflavone, and 5-hydroxy-2′-methoxyflavone using PMR
and mass spectrometry. It was proposed that the lack of growth of callus tissue after changing cultivation conditions was
related to the inhibiting effect of these flavones on cell proliferation.
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Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 440–442, September–October, 2005. 相似文献
16.
Isolation of lipase producer and its performance in enantioselective hydrolysis of glycidyl butyrate
A racemic glycidyl butyrate resolving strain, preliminarily identified as a Rhizopus sp., had been isolated from soil. Its extracellular lipase was found to enantioselectively hydrolyze the (S)-enantiomer of
the chiral ester, with optimal activities at pH 5.3 and 42°C. Higher en antioselectivity of theenzyme was observed at lower
temperatures, while the best anantioselectivity was obtained at pH 5.5–6.0, with an, E value (enantiomeric ratio) of 57. 相似文献
17.
The structural and dynamical properties of high-spin Ru2+ in aqueous solution have been theoretically studied using molecular dynamics (MD) simulations. The conventional MD simulation based on pair potentials gives the overestimated average first shell coordination number of 9, whereas the value of 5.9 was observed when the three-body corrected function was included. A combined ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulation has been performed to take into account the many-body effects on the hydration shell structure of Ru2+. The most important region, the first hydration shell, was treated by ab initio quantum mechanics at UHF level using the SBKJC VDZ ECP basis set for Ru2+ and the 6-31G∗ basis sets for water. An exact coordination number of 6 for the first hydration shell was obtained from the QM/MM simulation. The QM/MM simulation predicts the average Ru2+–O distance of 2.42 Å for the first hydration shell, whereas the values of 2.34 and 2.46 Å are resulted from the pair potentials without and with the three-body corrected simulations, respectively. Several other structural properties representing position and orientation of the solvate molecules were evaluated for describing the hydration shell structure of the Ru2+ ion in dilute aqueous solution. A mean residence time of 7.1 ps was obtained for water ligands residing in the second hydration shell. 相似文献
18.
Yagi Kiyohito Hamada Kenji Hlrata Kazumasa Miyamoto Kazuihisa Miura Yoshiharu Akano Tohru Fukatu Kiyomi Ikuta Yoshiaki Nakamura Hiroshi K. 《Applied biochemistry and biotechnology》1994,(1):225-232
A marine green alga,Chlamydomonas sp. strain MGA161 was cultivated under illumination of red and white lights. The growth rate under red light illumination
was almost the same as that in the basic conditions under white light illumination, but red light-grown cells accumulated
almost twice as much starch as white light-grown cells. Although there was a slight decrease in carbonic anhydrase activity,
red light-illuminated cells had almost 2.3 times the fructose-l,6-diphos-phatase activity of white light-illuminated cells.
Red light might stimulate starch accumulation by increasing the amounts of enzymes related to carbon fixation through the
phytochrome system. Cells grown under red light degraded 1.6 times as much starch and produced 1.7 times as much hydrogen
and 1.6 times as much ethanol compared with cells grown under white light during 12 h of dark anaerobic fermentation. 相似文献
19.
The rotation dynamics of C60 molecules in organic superconductor K3C60 has been investigated from the viewpoint of intramolecular interaction. It is determined that the rotation of C60 at mom temperature has been frozen up within a small region of rotation angle (0°–50°), and pointed out that the reason for
the freeze is the physical interaction rather than the geometrical hindrance. The computations of the interactions for alkali-doped
compounds A3-x
A′
x
C60 (x = 1, 2, 3; A, A′ = K, Rb, Cs) other than K3C60 have also been camed out. Fmm the obtained results, it is seen that the superconducting transition temperatures T, are strongly
connected with the interactions in them, and this observation is consistent with the discovery of the correlation between
Tc, and lattice constants a.
Project supported by the National Natural Science Foundation of China. 相似文献
20.
M. Walid Qoronfleh 《Applied biochemistry and biotechnology》1999,80(2):107-120
A central problem in aerobic growth of any culture is the maintenance of dissolved oxygen concentration (DOC) above growth-limiting
levels especially in high-cell density fermentations that are usually of the fed-batch type. Fermentor studies have been conducted
to determine the influence of DOC on the production of heterologous proteins in Escherichia coli. The results demonstrated that there is a significant degree of product-to-product variation in the response of heterologous
protein accumulation to DOC. For translational fusions of the human immunodeficiency virus-1 (HIV-1) proteins p24Gag and Env41,
the imposition of a dissolved oxygen (DO) limitation resulted in 100 and 15% increases in the respective product yields. On
the other hand, the imposition of a DO limitation had no effect on the production of a similar translational fusion of the
HIV-1 protein p55Gag, and a large negative effect on the production of an influenza protein (C13). The stimulatory effects
of DOC on p24Gag production were investigated further. The results of my studies suggested that the stimulatory effect observed
at reduced agitation rates on p24Gag accumulation was owing to an oxygen effect and not a shear effect. Furthermore, the results
of my investigations indicated that the effect a DOC had on the production of p24Gag was strongly influenced by the cell density
at which the culture was induced. 相似文献