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1.
Native fungal biomass of fungiAbsidia orchidis, Penicillium chrysogenum, Rhizopus arrhizus, Rhizopus nigricans, and modified spruce sawdust (Picea engelmanii) sequestered metals in the following decreasing preference pb>Cd>Ni. The highest metal uptake was qmax = 351 mg Pb/gA. orchidis biomass. P.chrysogenum biomass could accumulate cadmium best at 56 mg Cd/g. The sorption of nickel was the weakest always at < 5 mg Ni/g. The spruce
sawdust was modified by crosslinking, oxidation to acidic oxoforms, and by substitution. The highest metal uptake was observed
in phosphorylated sawdust reaching qmax = 224 mg Pb/g, 56 mg Cd/g, and 26 mg Ni/g. The latter value is comparable to the value of nickel sorption by wet commercial
resin Duolite GT-73. Some improvement in metal uptake was also observed after reinforcement of fungal biomass. 相似文献
2.
Pentacoordination of boron, carbon, aluminum, and silicon atoms in bicyclic organic compounds of the pentalene type was studied
using theab initio RHF/6-31G** and MP2(full)/6-31G** methods. It was shown that the ability of the atom to form pentacoordinate structures increases on going from B to Al and
from C to Si atom,i.e. as the number of the element of Groups IIIA and IVA of the periodic system increases. At the same time, the reverse tendencies
are observed in the 2nd and 3rd periods of the periodic system,viz., the ability of the atom to form pentacoordinate structures increases on going from C to B and from Al to Si atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1238–1245, July, 1999. 相似文献
3.
In an earlier binding study conducted in our laboratory using Thermobifida fusca cellulases Cel6B, Cel9A, and Cel5A (formally Thermomonospora fusca E3, E4, and E5), it was observed that binding capacities for these three cellulases were 18–30 times higher on BMCC than on Avicel. These
results stimulated an interest in how the difference in accessibility between the two cellulosic substrates would affect synergism
observed with cellulase mixtures. To explore the impact of substrate, accessibility on the extent of conversion and synergism,
three binary T. fusca cellulase mixtures were tested over a range of cellulase ratios and total molar cellulase concentrations on Avicel and BMCC.
Higher extents of conversion were observed for BMCC due to the higher enzyme to substrate ratio resulting from the higher
binding The processive endoglucanase, Cel9A, had four times the extent of conversion of the end endocellulase Cel5A, while
the exocellulase Cel6B had three times the extent of conversion of Cel5A. Approximately 500 nmol/g of the cel9A+Cel6B mixture
was needed to obtain 80% conversion, while the Cel6B+Cel5A and Cel9A+Cel5A mixtures required 1500 and 1250 nmol/g, respectively,
to obtain 80% conversion. Thus, it appears that the more accessible structure of BMCC, as reflected by its binding capacity,
results in relative higher processive activity. 相似文献
4.
Emri T Molnár Z Pusztahelyi T Rosén S Pócsi I 《Applied biochemistry and biotechnology》2004,118(1-3):337-348
The morphologic and physiologic effects of vitamin E, a powerful antioxidant, on the autolysis and sporulation of Aspergillus nidulans FGSC26 were studied. In carbon-depleted submerged cultures, reactive oxygen species (ROS) accumulated in the cells and, concomitantly,
progressing autolysis was observed, which was characterized by decreasing dry cell masses and pellet diameters as well as
by increasing extracellular chitinase activities. Vitamin E supplemented at a concentration of 1 g/L hindered effectively
the intracellular accumulation of ROS, the autolytic loss of biomass, the disintegration of pellets, and the release of chitinase
activities. In surface cultures, vitamin E inhibited autolysis of both A. nidulans FGSC26 and a loss-of-function FlbA autolytic phenotype mutant. In addition, supplementation of the culture medium with this antioxidant also had a negative
effect on the sporulation of strain FGSC26 and the FadA
G203R
hypersporulating phenotype mutant. These results suggest that accumulation of ROS was involved in the initiation of both
sporulation and autolysis in this filamentous fungus, but that FadA/FlbA signaling was not involved in this vitamin E-dependent
regulation. Vitamin E can be recommended as a supplement in fermentations in which the disintegration of pellets and gross
autolysis should be avoided. 相似文献
5.
A cassava flour-processing effluent (manipueira) was evaluated as a substrate for surfactant production by two Bacillus subtilis strains. B. subtilis ATCC 21332 reduced the surface tension of the medium to 25.9 mN/m, producing a crude biosurfactant concentration of 2.2 g/L.
The wild-type strain, B. subtilis LB5a, reduced the surface tension of the medium to 26.6 mN/m, giving a crude biosurfactant concentration of 3.0 g/L. A decrease
in surfactant concentration observed for B. subtilis ATCC 21332 seemed to be related to an increase in protease activity. The biosurfactant produced on cassava effluent medium
by B. subtilis LB5a was similar to surfactin. 相似文献
6.
E. E. Sirotkina A. I. Khlebnikov O. A. Napilkova 《Chemistry of Heterocyclic Compounds》2008,44(12):1505-1509
10-Propenylphenothiazine reacts with a catalytic amount of BF3·Et2O in dry ethyl acetate via intramolecular heterocyclization of an intermediate dimeric cation to give mainly 1-ethyl-2-methyl-3-(phenothiazin-10-yl)-2,3-dihydro-1H-pyrido[3,2,1-k,l]phenothiazine and a minor product through fission of phenothiazine which is 1-ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenothiazine. Under similar conditions 10-propenylphenoxazine gave an oligomer (degree of polymerization 4.4) and the minor
product 1-ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenoxazine likely formed similarly to the phenothiazine analog from the corresponding product of intramolecular heterocyclization
(the latter not being observed in the reaction mixture).
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1855–1860, December, 2008. 相似文献
7.
Akram M. El-Didamony 《Central European Journal of Chemistry》2005,3(3):520-536
Three simple, accurate, and sensitive spectrophotometric methods (A, B and C) have been described for the indirect assay of
diltiazem hydrochloride (DIL.HCl), either in pure form or in pharmaceutical formulations. The first method (A) is based on
the oxidation of DIL.HCl by N-bromosuccinimide (NBS) and determination of unconsumed NBS by measuring the decrease in absorbance
of amaranth dye (AM) at a suitable λ
max
=521 nm. Other methods (B) and (C) involve the addition of excess cerric ammonium sulfate (CAS) and subsequent determination
of the unconsumed oxidant by a decrease in the red color of chromotrope 2R (C2R) at a suitable λ
max
=528 nm or a decrease in the orange-pink color of rhodamine 6G (Rh6G) at λ
max
=525 nm, respectively. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 3.0–9.0,
3.5–7.0 and 3.5–6.3 μg ml−1 for methods A, B and C, respectively. The apparent molar absorptivity, Sandell's sensitivity, detection and quantification
limits were calculated. The proposed methods have been applied successfully for the analysis of the drug in its pure form
and its dosage form. No interference was observed from a common pharmaceutical adjuvant. Statistical comparison of the results
with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. 相似文献
8.
T. N. Makarieva A. G. Guzii V. A. Denisenko P. S. Dmitrenok V. A. Stonik 《Russian Chemical Bulletin》2008,57(3):669-673
New two-headed sphingolipid-like compounds, rhizochalin B and rhizochalinin B, containing a butoxy group, which is rarely
encountered in natural products, were isolated as peracetates from the marine sponge Oceanapia sp. Their structures were established by NMR spectroscopic and MALDI TOF and HRESI TOF MS methods.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 656–660, March, 2008. 相似文献
9.
A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization oftrans- andcis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the
five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in
the presence of the Ph3P−CBr4−Et3N system. (Pr2BH)2 and Pr3B are used as the hydroborating reagents, and H2O2 in an acid medium is used for the oxidation of 2-[3-(dipropylboryl]-Δ2-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and itstrans-isomer were prepared fromcis- andtrans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B andtrans-5-propylindolizidine were synthesized fromcis- andtrans-2,6-diallyl-1,2,3,6-tetra-hydropyridine, respectively.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 971–979, May, 1998. 相似文献
10.
K. W. Lo H. Chua H. Lawford W. H. Lo Peter H. F. Yu 《Applied biochemistry and biotechnology》2005,122(1-3):575-580
The effects of saturated and unsaturated fatty acids (lauric acid, palmitic acid, steric acid, oleic acid, linoleic acid,
soybean oil) on Sphaerotilus natans, 0B17 (Pseudomonas sp.), and recombinant Escherichia coli DH5(/pUC19/CAB were studied. Oleic acid enhances Poly-3-hydroxybutyrate (PHB) production in these three bacterial strains, suggesting that
the single double bond of the acid activates the polyhydroxylkanoate accumulation enzymatic reaction. Under the effect of
lauric acid and linoleic acid, the growth of S. natans and 0B17 were totally inhibited. However, the enhanced PHB accumulation in recombinant E. coli was observed. 相似文献
11.
N. V. Ivanchina T. V. Malyarenko A. A. Kicha A. I. Kalinovskii P. S. Dmitrenok 《Russian Chemical Bulletin》2008,57(1):204-208
Nine steroidal compounds including three new steroidal glycosides, viz., sodium (24S)-3,24-di-O-(β-D-xylopyranosyl)-5α-cholestane-3β,6β,8,15α,24-pentol 15-sulfate (fuscaside A), (24S)-3,24-di-O-(β-D-xylopyranosyl)-5α-cholestane-3β,6β,8,15α,24-pentol (fuscaside B), and (22E,24R)-24-O-(β-D-xylopyranosyl)-5α-cholest-22-ene-3β,6α,8,15β,24-pentol (desulfated minutoside A); three previously known glycosides, viz., distolasterosides D1 and D2 and pycno-podioside A; two previously known polyhydroxysteroids, viz., 5α-cholestane-3β,6α,8,15β,16β,26-hexaol and 5α-cholestan-3β,4β,6α,7⇇8,15β,16β,26-octol; and the known sodium 24,25-dihydro-marthasterone
3-sulfate were isolated from the Far-Eastern starfish Lethasterias fusca. The structures of these compounds were elucidated by NMR spectroscopy and mass spectrometry.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 196–200, January, 2008. 相似文献
12.
Marko D. Mihovilovic Bernhard Müller Markus Spina Arjumand I. Durrani Peter Stanetty Georg Dazinger Karl Kirchner 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):785-794
Summary. Recombinant Escherichia coli overexpressing Pseudomonas sp. NCIMB 9872 cyclopentanone monooxygenase (CPMO, EC 1.14.13.16) and Acinetobacter sp. NCIMB 9871 cyclohexanone monooxygenase (CHMO, EC 1.14.13.22) have been utilized in whole-cell Baeyer-Villiger biotransformations of prochiral bicycloketones. A significant difference in substrate acceptance and stereoselectivity was
observed for bicyclo[3.3.0] and bicyclo[4.3.0] substrates. A plausible mechanism of these transformations was established
by means of high level DFT/B3LYP calculations suggesting an essential difference in electronic requirements for a successful
enzymatic conversion, which was similarly encountered in recombinant whole-cell mediated biooxidations. Some of the lactones
produced in the biocatalytic Baeyer-Villiger oxidation represent key intermediates for the synthesis of indole alkaloids. 相似文献
13.
Infrared andRaman vibrational spectra ofn-Si4Cl10,n-Si5Cl12,neo-Si5Cl12 and [(SiCl3)3Si]2 have been measured and assigned. A local symmetry force field has been developed to simulate vibrational spectra of all (noncyclic) perchlorosilanes Si
n
Cl2n+2 known today (n=2, 3, 4, 5, 8). The observed spectra are reproduced satisfactorily
Die Vibrationsspektren linearer und verzweigter PerchlorsilaneSi n Cl 2n+2 und deren Simulierung mittels eines lokalen Symmetrie-Kraftfeldes
Zusammenfassung Infrarot- undRaman-Spektren vonn-Si4Cl10,n-Si5Cl12,neo-Si5Cl12 und [(SiCl3)3Si]2 wurden aufgenommen und zugeordnet. Ein lokales Symmetrie-Kraftfeld zur Simulation der Spektren aller bisher bekannten (nicht cyclischen) Perchlorsilane Si n Cl2n+2 (n=2, 3, 4, 5, 8) wird angegeben. Die beobachteten Spektren werden zufriedenstellend reproduziert相似文献
14.
Cloning, characterization, and expression of a new cry2Ab gene from Bacillus thuringiensis strain 14-1 总被引:2,自引:0,他引:2
Jain D Udayasuriyan V Arulselvi PI Dev SS Sangeetha P 《Applied biochemistry and biotechnology》2006,128(3):185-194
Bacillus thuringiensis is the major source for transfer of genes to impart insect resistance in transgenic plants. Cry2A proteins of B. thuringiensis are promising candidates for management of resistance development in insects owing to their difference from the currently
used Cry1A proteins, in structure and insecticidal mechanism. The cry2Ab gene was found to lack a functional promoter and, hence, is cryptic in nature. The cry2Ab7 gene was cloned from a new indigenous B. thuringiensis strain, 14-1. Nucleotide sequencing of the cry2Ab gene cloned from B. thuringiensis strain 14-1 revealed an open reading frame of 1902 bp. The deduced amino acid sequence of Cry2Ab of B. thuringiensis strain 14-1 showed a variation in three amino acid residues in comparison to the holotype sequence, Cry2Ab1. Expression of
the newly cloned cry2Ab gene was studied in an acrystalliferous strain of B. thuringiensis (4Q7) by fusing the cry2Ab gene downstream of cry2Aa promoter and orf1+orf2 sequences. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of a spore-crystal mixture obtained from transformants
of B. thuringiensis strain 4Q7 showed production of Cry2Ab protein of about 65 kDa. Alkali solubilized Cry2Ab7 protein showed toxicity against
Helicoverpa armigera neonates. 相似文献
15.
Lanosterol was converted by degradation of the side chain followed by transformations within rings B and C into a series of 9,11-epoxy-7-oxo-4,4,14-trimethylsteroids.Part IV.Paryzek, Z., Wydra, R., Bull. Acad. Polon. Sci., Ser. sci. chim.26, 591 (1978). 相似文献
16.
The kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine
(E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO4 was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT]
o
, fractional-order in [substrate]
o
, and inverse fractional-order in [H+]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The
variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect
on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was
studied using D2O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for
CAT-catecholamine complexes have been evaluated. CH3C6H4SO2NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic
relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed
and the derived rate law are consistent with the observed kinetics. 相似文献
17.
Summary A high-performance liquid chromatographic method for the separation and determination of gastrodin,p-hydroxybenzyl alcohol, vanillyl alcohol,p-hydroxylbenzaldehyde and vanillin in extract of Chinese herbal medicine tall gastrodia tuber (Chinese name: Tianma) was established.
The chromatographic conditions were optimized by means of computer-assisted method development technique. Dry-Lab software
was used to model the retention behavior of the compounds as a function of gradient conditions, based on the data from two
scouting gradient runs. Under the optimized conditions: column, Kromasil-C18, 5 μm, 15×0.46-cm; solvent A, water; solvent
B, methanol; gradient, 5/44/65/65% B at 0/9/12/15 min; flow rate, 1.00 mL min−1; temperature, ambient, the quality of tall gastrodia tubers from different sources and tianma injection were examined. 相似文献
18.
Dimitrovska Sandra Aleksovska Slobotka Kuzmanovski Igor 《Central European Journal of Chemistry》2005,3(1):198-215
The unit cell edge length, a, of a set of complex cubic perovskites having the general formula A
2
2+
BB′O6 is predicted using two methodologies: multiple linear regression and artificial neural neworks. The unit cell edge length
is expressed as a function of six independent variables: the effective ionic radii of the constituents (A, B and B′), the
electronegativities of B and B′, and the oxidation state of B. In this analysis, 147 perovskites of the A
2
2+
BB′O6 type, having the cubic structure and belonging to the Fm3m space group, are included. They are divided in two sets; 98 compounds are used in the calibration set and 49 are used in
the test set. Both models give consistent results and could be successfully use to predict the lattice cell parameter of new
members of this series. 相似文献
19.
首次利用薯蓣皂甙元的完整骨架经16步反应以7.6%的总收率合成了骨化三醇(1α,25-二羟基维生素D3)的光化反应前体. 3-苄基保护的薯蓣皂甙元经还原开E/F环产生3,16,26-胆甾三醇-3-苄醚(5). 除去化合物5 C-16羟基后, 其C-26羟基经消除和羟基化反应转移到C-25位. 目标分子A/B环结构单元通过薯蓣皂甙元A/B环的官能团转化被构筑. 按照已知的光化反应, (1S,3R)-胆甾-5,7-二烯-1,3,25-三醇能被转化成为1α,25-二羟基维生素D3. 相似文献
20.
It is commonly observed that the rate of enzymatic hydrolysis of solid cellulose substrates declines markedly with time. In
this work the mechanism behind the rate reduction was investigated using two dominant cellulases of Trichoderma reesei: exoglucanase Cel7A (formerly known as CBHI) and endoglucanase Cel7B (formerly EGI). Hydrolysis of steam-pretreated spruce
(SPS) was performed with Cel7A and Cel7B alone, and in reconstituted mixtures. Throughout the 48-h hydrolysis, soluble products,
hydrolysis rates, and enzyme adsorption to the substrate were measured. The hydrolysis rate for both enzymes decreases rapidly
with hydrolysis time. Both enzymes adsorbed rapidly to the substrate during hydrolysis. Cel7A and Cel7B cooperate synergistically,
and synergism was approximately constant during the SPS hydrolysis. Thermal instability of the enzymes and product inhibition
was not the main cause of reduced hydrolysis rates. Adding fresh substrate to substrate previously hydrolyzed for 24 h with
Cel7A slightly increased the hydrolysis of SPS; however, the rate increased even more by adding fresh Cel7A. This suggests
that enzymes become inactivated while adsorbed to the substrate and that unproductive binding is the main cause of hydrolysis
rate reduction. The strongest increase in hydrolysis rate was achieved by adding Cel7B. An improved model is proposed that
extends the standard endo-exo synergy model and explains the rapid decrease in hydrolysis rate. It appears that the processive
action of Cel7A becomes hindered by obstacles in the lignocellulose substrate. Obstacles created by disordered cellulose chains
can be removed by the endo activity of Cel7B, which explains some of the observed synergism between Cel7A and Cel7B. The improved
model is supported by adsorption studies during hydrolysis. 相似文献