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1.
The blue-green algaMicrocystis aeruginosa contains a branched glucan constructed of D-glucopyranose residues with α-1,4 bonds in the main chain and α-1,6 bonds at
the points of branching. 相似文献
2.
N. M. Shevchenko Yu. V. Burtseva T. N. Zvyagintseva T. N. Makar′eva O. S. Sergeeva A. M. Zakharenko V. V. Isakov Nguyen Thi Linh Nguyen Xuan Hoa Bui Minh Ly Pham Van Huyen 《Chemistry of Natural Compounds》2009,45(1):1-5
Sterols and polysaccharides of green alga Caulerpa lentillifera grown under laboratory conditions and in mariculture and polysaccharides of green alga C. sertularioides grown under natural conditions were studied. The sterol fraction consisted of C27-C29 steroidal alcohols with Δ5-unsaturation in the steroid core regardless of the growth conditions. The dominant (79.9%) steroid component of the sterol
fraction was clionasterol. The water-soluble fraction of C. lentillifera grown under laboratory conditions was a mixture of 1,4-α- and 1,3-β-D-glucans and protein. The same fraction isolated from C. lentillifera grown in mariculture contained only protein. The water-soluble fraction of C. sertularioides grown under natural conditions contained 1,3;1,6-β-D-galactan sulfated at C2. The principal components of the base-soluble polysaccharide fractions from all algae samples were
1,4-α-D-glucans.
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 5-8, January-February, 2009. 相似文献
3.
The action modes of an oligosaccharide-producing multifunctional amylase (OPMA) were investigated using glucose and some oligosaccharides
as its substrates. OPMA did not cause the hydrolysis of maltose or isomaltose, but it catalyzed the α-1,6-transglycosylation
of maltose to produce isomaltose or did the self-condensation of isomaltose to form isomaltotetraose and 4-O-α-isomaltosyl
isomaltose. OPMA exhibited strong α-1,6-transglycosylation activity in addition to its α-1,4-hydrolytic activity on higher
oligosaccharides substrates rather than bisaccharides. OPMA displayed high acceptor specificity in its transglycosylation
or condensation reaction. OPMA seemed to only take glucose or isomaltose as the acceptor molecule in its transglycosylation
or condensation reaction, which made glucose or isomaltose form higher products, and as a result, glucose or isomaltose were
absent in the final products. In view of the simultaneously formation of several transglycosylation or condensation products,
it was predicted that there might be separate donor and acceptor sites in OPMA’s active center and the fact that the catalytically
active form of this enzyme included its homodimer or homotrimer supported this prediction. Accordingly, a special pathway,
isomaltose pathway, for OPMA catalysis was proposed to emphasize the central or important signification of isomaltose in OPMA
catalysis. 相似文献
4.
Comparison and characterization of polysaccharides from natural and cultured Cordyceps on the basis of their chemical characteristics such as glycosidic linkages were performed for the first time using saccharide
mapping. The results showed that polysaccharides from most of the natural and cultured Cordyceps had similar responses to enzymatic digestion. These polysaccharides mainly contained (1→4)-β-D-glucosidic linkages, and (1→4)-α-glucosidic, (1→6)-α-glucosidic, 1,4-β-D-mannosidic, as well as (1→4)-α-D-galactosiduronic linkages also existed in some polysaccharides. Especially, natural and cultured Cordyceps polysaccharides could be discriminated on the basis of high performance liquid chromatography profiles of pectinase hydrolysates,
which is helpful to control the quality of polysaccharides from Cordyceps. 相似文献
5.
Zaghloul Taha I. Abdel Wahab Abir E. Mostafa Mostafa H. 《Applied biochemistry and biotechnology》2000,84(1-9):319-327
Bacillus subtilis Bios 11 strain was previously isolated and identified. This strain naturally produces a high level of α-amylase. The multicopy
(pS1) plasmid that carries the complete alkaline protease aprA gene was introduced to this host strain by transformation. The newly constructed strain was found to express the aprA gene and produces a high level of alkaline protease. The level of α-amylase production was not affected compared with the
parent strain. The pS1 plasmid in the new host was proved to be segregationally and structurally stable, and the multicopy
aprA gene was expressed at the stationary phase. This expression did not affect growth rate and sporulation frequency. Moreover,
the level of α-amylase was maintained. Both alkaline protease and α-amylase enzymes were purified using a single-step affinity
chromatography column. The use of the newly constructed strain would be valuable to the enzyme industry and would promote
recycling of some food-processing wastes. 相似文献
6.
Nilsson C Nilsson F Turner P Sixtensson M Nordberg Karlsson E Holst O Cohen A Gorton L 《Analytical and bioanalytical chemistry》2006,385(8):1421-1429
In this work, a real-time sampling/analytical method for on-line measurements of two newly discovered cyclomaltodextrinases
(CDases) has been developed and evaluated. This novel methodology not only allows the final products to be investigated, but
it also reveals enzyme-specific differences in the degradation pathways during the hydrolysis of different substrates, which
is a great advantage in the important tasks of investigating the mechanisms of and classifying new hydrolases, and is an advantage
that conventional techniques cannot offer. Two different enzymes, one CDase from Laceyella
sacchari (LsCda13) and one from Anoxybacillus flavithermus (AfCda13), were investigated during the hydrolysis of α-, β- and γ-cyclodextrin, and the hydrolysis products were sampled via
a microdialysis probe and injected on-line every 30 min into a high-performance anion exchange chromatography system equipped
with a pulsed amperometric detector (HPAEC–PAD), where they were identified. The enzymes yielded the same end-products, maltose
and glucose, in an approximate molar ratio of 2:1, but they exhibited distinctly different patterns of intermediate product
formation before reaching the end-point. LsCda13 had a more random distribution of the intermediate products, whereas AfCda13 showed the distinct intermediate production of maltotriose, which in some cases accumulated. 相似文献
7.
A monoclonal antibody (MAb) against amylase-pullulanase enzyme fromBacillus circulons, which hydrolyzes not only theα-1,6-glycosidic linkage but also theα-1,4-glycosidic linkage to the same extent, has been produced by the fusion of BALB/c mouse spleen cells immunized with the
native enzyme and P3x63Ag8U1 myeloma cells, and examined for inhibition of pullulanase activity in order to characterize the
catalytic site of the pullulanase. The MAb recognizes active enzyme, but not the SDS-denatured or heat-inactivated protein,
indicating that the antibody is highly conformational-dependent, specific for active enzyme. The antibody inhibited the pullulanase
activity, but not amylase activity. The monoclonal antibody immunoblotted the enzyme and immunoprecipitated the enzyme. The
immunoprecipitation was inhibited in the presence of substrate, pullulan, and the MAb competitively inhibited the binding
of pullulan to the enzyme. The MAb, therefore, recognizes the pullulanbinding site of the enzyme. Kinetic analysis showed
that the MAb inhibited pullulanase activity with inhibition constant (K
i
,) of 0.77Μg/mL, providing evidence that the antibody decreases the catalytic rate of enzyme activity and has an effect on
substrate binding. These results strongly confirm the previous observations that APE may have two different active sites responsible
for the expression of amylase and pullulanase activities (Kim, C. H. and Kim, Y. S.Eur. J. Biochem. 1995,227, 687–693). 相似文献
8.
Production of Cyclodextrins by CGTase from Bacillus clausii Using Different Starches as Substrates 总被引:1,自引:0,他引:1
Alves-Prado HF Carneiro AA Pavezzi FC Gomes E Boscolo M Franco CM da Silva R 《Applied biochemistry and biotechnology》2008,146(1-3):3-13
Cyclodextrins (CDs) are cyclic oligasaccharides composed by d-glucose monomers joined by α-1,4-d glicosidic linkages. The main types of CDs are α-, β- and γ-CDs consisting of cycles of six, seven, and eight glucose monomers,
respectively. Their ability to form inclusion complexes is the most important characteristic, allowing their wide industrial
application. The physical property of the CD-complexed compound can be altered to improve stability, volatility, solubility,
or bio-availability. The cyclomaltodextrin glucanotransferase (CGTase, EC 2.4.1.19) is an enzyme capable of converting starch
into CD molecules. In this work, the CGTase produced by Bacillus clausii strain E16 was used to produce CD from maltodextrin and different starches (commercial soluble starch, corn, cassava, sweet
potato, and waxy corn starches) as substrates. It was observed that the substrate sources influence the kind of CD obtained
and that this CGTase displays a β-CGTase action, presenting a better conversion of soluble starch at 1.0%, of which 80% was
converted in CDs. The ratio of total CD produced was 0:0.89:0.11 for α/β/γ. It was also observed that root and tuber starches
were more accessible to CGTase action than seed starch under the studied conditions. 相似文献
9.
Glycosyl hydrolase family 16 (GHF16) truncated Fibrobacter succinogenes (TFs) and GHF17 barley 1,3-1,4-β-d-glucanases (β-glucanases) possess different structural folds, β-jellyroll and (β/α)8, although they both catalyze the specific hydrolysis of β-1,4 glycosidic bonds adjacent to β-1,3 linkages in mixed β-1,3
and β-1,4 β-d-glucans or lichenan. Differences in the active site region residues of TFs β-glucanase and barley β-glucanase create binding
site topographies that require different substrate conformations. In contrast to barley β-glucanase, TFs β-glucanase possesses
a unique and compact active site. The structural analysis results suggest that the tyrosine residue, which is conserved in
all known 1,3-1,4-β-d-glucanases, is involved in the recognition of mixed β-1,3 and β-1,4 linked polysaccharide. 相似文献
10.
Nicolas Smiljanic Vincent Moreau Duplex Yockot Jose Manuel García Fernández Florence Djedaïni-Pilard 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):9-14
An original synthetic route based on multi-glycosylation and selective protection–deprotection steps has been developed which
allows a fast access to complex oligomannosides with both α-(1,3),α-(1,6) and α-(1,3),α-(1,4) cores. The later have been linked
to modified β-cyclodextrins bearing spacing arms of varying chemical structure and length through peptidic-like coupling,
leading to the formation of a range of oligomannosyl cyclodextrin conjugates. Complexation studies with sodium anthraquinone-2-sulfonate
(ASANa) and sodium adamantane 1-carboxylate (ACNa) as guest molecules demonstrated that the β-cyclodextrin inclusion properties
are preserved. Binding affinity studies using the mannose specific lectin Concanavalin A (Con A) demonstrated the key role
of the density and tridimensional structure of the sugar ligand in recognition events. 相似文献
11.
Thermomucor indicae-seudaticae, a glucoamylase-producing thermophilic mould, was mutagenised using nitrous acid and gamma (60Co) irradiation in a sequential manner to isolate deregulated mutants for enhanced production of glucoamylase. The mutants
were isolated on Emerson YpSs agar containing a non-metabolisable glucose analogue 2-deoxy-d-glucose (2-DG) for selection. The preliminary screening for glucoamylase production using starch–iodine plate assay followed
by quantitative confirmation in submerged fermentation permitted the isolation of several variants showing varying levels
of derepression and glucoamylase secretion. The mutant strain T. indicae-seudaticae CR19 was able to grow in the presence of 0.5 g l−1 2-DG and produced 1.8-fold higher glucoamylase. As with the parent strain, glucoamylase production by T. indicae-seudaticae CR19 in 250-ml Erlenmeyer flasks attained a peak in 48 h of fermentation, showing higher glucoamylase productivity (0.67 U
ml−1 h−1) than the former (0.375 U ml−1 h−1). A large-scale cultivation in 5-l laboratory bioreactor confirmed similar fermentation profiles, though the glucoamylase
production peak was attained within 36 h attributable to the better control of process parameters. Although the mutant grew
slightly slow in the presence of 2-DG and exhibited less sporulation, it showed faster growth on normal Emerson medium with
a higher specific growth rate (0.138 h−1) compared to the parent strain (0.123 h−1). The glucoamylase produced by both strains was optimally active at 60 °C and pH 7.0 and displayed broad substrate specificity
by cleaving α-1,4- and α-1,6-glycosidic linkages in starch, amylopectin, amylose and pullulan. Improved productivity and higher
specific growth rate make T. indicae-seudaticae CR19 a useful strain for glucoamylase production. 相似文献
12.
K. I. Pashkevich V. I. Filyakova V. G. Ratner O. G. Khomutov 《Russian Chemical Bulletin》1998,47(7):1239-1247
Efficient procedures for the regioselective synthesis of fluoroalkyl-containing threefive-, six-, and seven-membered heterocycles
as well as of related fused compounds, namely, α,β-epoxyketones, α,β-aziridinylketones, pyrazoles, pyrazolines, isoxazolines,
1,2-dithiolenes, amino- and mercaptopyrimidines, Δ3,5-2-thioxo-1,3,2-thiazaphosphorines, Δ3,5-2-thioxo-1,3,2-oxazaphosphorines, 2,3-dihydro-1,4-diazepines, azirino[1,2-a]quinoxalines, benzo[b]-and naphtho[2,3-b]-1,4-diazepines, and triazolopyridazines, which have been developed by the authors and coworkers, are summarized. The α-
and β-functionalized fluoroalkylcontaining carbonyl compounds (β-diketones, β-ketoesters, their salts, regioisomeric β-aminovinyl
ketones, β-aminovinylthiones, β-hydroxyketones, α,β-enones, and their halogen derivatives) were used as synthons in the processes
of formation of the above-mentioned heterocycles.
Dedicated to the memory of Academician I. Ya. Postovskii on his 100th birthday.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1279–1286, July, 1998. 相似文献
13.
Ferreira JG Reis AP Guimarães VM Falkoski DL Fialho Lda S de Rezende ST 《Applied biochemistry and biotechnology》2011,164(7):1111-1125
α-Galactosidases has the potential to hydrolyze α-1-6 linkages in raffinose family oligosaccharides (RFO). Aspergillus terreus cells cultivated on wheat bran produced three extracellular forms of α-galactosidases (E1, E2, and E3). E1 and E2 α-galactosidases
presented maximal activities at pH 5, while E3 α-galactosidase was more active at pH 5.5. The E1 and E2 enzymes showed stability
for 6 h at pH 4–7. Maximal activities were determined at 60, 55, and 50°C, for E1, E2, and E3 α-galactosidase, respectively.
E2 α-galactosidase retained 90% of its initial activity after 70 h at 50°C. The enzymes hydrolyzed ρNPGal, melibiose, raffinose
and stachyose, and E1 and E2 enzymes were able to hydrolyze guar gum and locust bean gum substrates. E1 and E3 α-galactosidases
were completely inhibited by Hg2+, Ag+, and Cu2+. The treatment of RFO present in soy milk with the enzymes showed that E1 α-galactosidase reduced the stachyose content to
zero after 12 h of reaction, while E2 promoted total hydrolysis of raffinose. The complete removal of the oligosaccharides
in soy milk could be reached by synergistic action of both enzymes 相似文献
14.
Purification of β-1,3-1,4-glucanase from the cell-free culture fluid of Bacillus subtilis GN156 by affinity chromatography of epoxy-activated sepharose 6B and ultrafiltration technique resulted in homogeneous J1
and partially purified pJ2 enzymes. The molecular weight and pI of J1 were 25 kDa and 3.5, respectively, while those for J2 were 90 kDa and 3.6, respectively. Both β-1,3-1,4-glucanase J1
and pJ2 had optimum pH values of 6–6.5 and an optimum temperature of 60°C. Both enzymes were not inhibited by Li2+ but were inhibited significantly by Ca2+, Cu2+, Mn2+ and Zn2+. However, J1 was slightly inhibited by Fe2+, while pJ2 was inhibited by Mg2+ as well. They were highly specific to only barley β-glucan. K
m and V
max values of J1 were 1.53 mg/ml and 8,511 μU/ml.min, respectively, while those for pJ2 were 4.36 mg/ml and 7,397 μU/ml.min,
respectively. Degradation of barley β-1, 3-1,4-glucan resulted in four different oligosaccharides with 1,3 linkages triose,
tetrose, pentose and a high molecular weight (HMW) with 1,3 linkage estimated from their mobilities. The quantitative degradation
by the crude enzyme after of incubation yielded in descending order: triose, pentose and tetrose, while that of J1 in descending
order yielded: pentose, triose and tetrose. The pJ2 showed low activity yielding a degradation pattern in descending order:
pentose, triose, tetraose and a HMW polysaccharide. 相似文献
15.
Extraction and characterization of native heteroxylans from delignified corn stover and aspen 总被引:1,自引:0,他引:1
Radnaa Naran Stuart Black Stephen R. Decker Parastoo Azadi 《Cellulose (London, England)》2009,16(4):661-675
Dimethylsulfoxide-solubilized polysaccharides from delignified corn stover and aspen were characterized. The biomass was delignified
by two different techniques; a standard acid chlorite and a pulp and paper QPD technique comprising chelation (Q), peroxide
(P), and acid-chlorite (D). Major polysaccharides in all fractions were diversely substituted xylan. Xylan acetylation was
intact after chlorite delignification and, as expected, xylan from QPD-delignified fraction was de-acetylated by the alkaline
peroxide step. The study of DMSO-extractable xylans from chlorite-delignified biomass revealed major differences in native
acetylation patterns between corn stover and aspen xylan. Xylan from cell walls of corn stover contains 2-O- and 3-O-mono-acetylated xylan and [MeGlcA-α-(1 → 2)][3-OAc]-xylp units. In addition, aspen xylan also contains 2,3-di-O-acetylated xylose. 1,4-β-d-xylp residues substituted with MeGlcA at O-2 position are absent in chlorite-delignified aspen xylan. Sugar composition in accord with NMR-spectroscopic data indicated
that corn stover xylan is arabinosylated while aspen xylan is not. We have shown that corn stover xylan has similar structure
with xylans from other plants of Poales order. No evidence was found to indicate the presence of 1,4-β-d-[MeGlcA-α-(1 → 2)][Ara-α-(1 → 3)]-xylp in corn stover xylan fractions. 相似文献
16.
Effects of pH and Temperature on Recombinant Manganese Peroxidase Production and Stability 总被引:1,自引:0,他引:1
Jiang F Kongsaeree P Schilke K Lajoie C Kelly C 《Applied biochemistry and biotechnology》2008,146(1-3):15-27
The enzyme manganese peroxidase (MnP) is produced by numerous white-rot fungi to overcome biomass recalcitrance caused by
lignin. MnP acts directly on lignin and increases access of the woody structure to synergistic wood-degrading enzymes such
as cellulases and xylanases. Recombinant MnP (rMnP) can be produced in the yeast Pichia pastoris αMnP1-1 in fed-batch fermentations. The effects of pH and temperature on recombinant manganese peroxidase (rMnP) production
by P. pastoris αMnP1-1 were investigated in shake flask and fed-batch fermentations. The optimum pH and temperature for a standardized fed-batch
fermentation process for rMnP production in P. pastoris αMnP1-1 were determined to be pH 6 and 30 °C, respectively. P. pastoris αMnP1-1 constitutively expresses the manganese peroxidase (mnp1) complementary DNA from Phanerochaete chrysosporium, and the rMnP has similar kinetic characteristics and pH activity and stability ranges as the wild-type MnP (wtMnP). Cultivation
of P. chrysosporium mycelia in stationary flasks for production of heme peroxidases is commonly conducted at low pH (pH 4.2). However, shake
flask and fed-batch fermentation experiments with P. pastoris αMnP1-1 demonstrated that rMnP production is highest at pH 6, with rMnP concentrations in the medium declining rapidly at
pH less than 5.5, although cell growth rates were similar from pH 4–7. Investigations of the cause of low rMnP production
at low pH were consistent with the hypothesis that intracellular proteases are released from dead and lysed yeast cells during
the fermentation that are active against rMnP at pH less than 5.5. 相似文献
17.
Multi-component condensation of cyanoselenoacetamide with ethyl 2-furfuryl-idenacetoacetate and liquid alkyl halides, catalyzed
byN-methylmorpholine, affords 7-alkylseleno-5-amino-8-cyano-3-ethoxycarbonyl-4-(2-furyl)-2-methyl-1,4-dihydro-1,6-naphthyridines,
which have not been described hitherto.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 121–124, January, 2000. 相似文献
18.
Multi-component condensation of cyanoselenoacetamide with ethyl 2-furfuryl-idenacetoacetate and liquid alkyl halides, catalyzed
byN-methylmorpholine, affords 7-alkylseleno-5-amino-8-cyano-3-ethoxycarbonyl-4-(2-furyl)-2-methyl-1,4-dihydro-1,6-naphthyridines,
which have not been described hitherto.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 121–124, January, 2000. 相似文献
19.
A. S. Merenga C. M. Papadakis F. Kremer J. Liu A. F. Yee 《Colloid and polymer science》2001,279(11):1064-1072
Broadband dielectric spectroscopy (1–106 Hz, 183–423 K) and differential scanning calorimetry are employed to analyze the inter- and intramolecular dynamics of a
series of random copolymers based on poly(ethylene terephthalate) and poly(1,4-cyclohexylene dimethylene terephthalate). In
addition to an interfacial relaxation (α*-process), three dielectric relaxation processes are observed: The α-relaxation (“dynamic
glass transition”) and two secondary relaxations (β- and β*-relaxations). The α-relaxation depends sensitively on the composition
of the copolymer and shows a rapid slowing down with increasing content of cyclohexylene dimethylene (CHDM) linkages. Besides
the β-relaxation, attributed to local motion of the ester group, an additional process (β*-relaxation) is observed on introducing
the CHDM linkages. Increasing the content of the latter reduces the strength of the β-relaxation strongly and increases its
activation energy by more than 30%. This proves that owing to interactions between the cylohexylene rings and the ester group
the β-relaxation no longer has local character only.
Received: 28 September 2000 Accepted: 29 January 2001 相似文献
20.
Lei Shi Kaoshan Chen Qun Dong Jinian Fang Kan Ding 《Frontiers of Chemistry in China》2008,3(2):209-212
A water-soluble polysaccharide (CPS-0) was obtained from the root of Cudrania tricuspidata (Carr.) Bur., by hot water extraction (70°C), deproteination using enzymolysis and Sevag method, precipitation with ethanol,
and fractionation through DEAE-Sephadex A-50 chromatography. The purity of CPS-0 was determined by HPLC and the structure
was elucidated by monosaccharide composition analysis, methylation analysis, GC, GC-MS, NMR spectral (1H-NMR, 13C-NMR, HMQC), UV, IR, and elemental analysis. The CPS-0 was found to contain glucose residues only. The average repeating
unit is a decasaccharide having a backbone consisting of 1,4-linked α-D-glucopyranosyl residues to which the side chain consisting of terminal and 1,4-linked α-D-glucopyranosyl residues was attached at position 6 of the branching residues.
__________
Translated from Chemical Journal of Chinese Universities, 2007, 28(6): 1088–1091 [译自: 高等学校化学学报] 相似文献