共查询到10条相似文献,搜索用时 118 毫秒
1.
Abronina P. I. Galkin K. I. Backinowsky L. V. Grachev A. A. 《Russian Chemical Bulletin》2009,58(2):457-467
Block synthesis of a fully benzoylated derivative of the pentasaccharide α-d-Manp-(1→3)-α-d-Manp-(1→2)-α-d-Manp-(1→2)-α-d-Manp-(1→2)-α-d-Manp-SCH2CH2CO2Me, the glycoside of the repeating unit of the O-antigenic polysaccharide of the bacterium Klebsiella pneumoniae O3, was performed. 相似文献
2.
Dicko MH Searle-van Leeuwen MJ Traore AS Hilhorst R Beldman G 《Applied biochemistry and biotechnology》2001,94(3):225-241
The leaves of Boscia senegalensis are traditionally used in West Africa in cereal protection against pathogens, pharmacologic applications, and food processing.
Activities of α-amylase, β-amylase, exo-(1→3, 1→4)-β-d-glucanase, and endo-(1→3)-β-d-glucanase were detected in these leaves. The endo-(1→3)-β-d-glucanase (EC3.2.1.39) was purified 203-fold with 57% yield. The purified enzyme is a nonglycosylated monomeric protein with
a molecular mass of 36 kDa and pI≥10.3. Its optimal activity occurred at pH 4.5 and 50°C. Kinetic analysis gave V
max, k
cat
, and K
m
values of 659 U/mg, 395 s−1, and 0.42 mg/mL, respectively, for laminarin as substrate. The use of matrix-assisted laser desorption ionization time-of-flight
mass spectrometry and high-performance liquid chromatography revealed that the enzyme hydrolyzes not only soluble but also
insoluble (1→3)-β-glucan chains in an endo fashion. This property is unusual for endo-acting (1→3)-β-d-glucanase from plants. The involvement of the enzyme in plant defense against pathogenic microorganisms such as fungi is
discussed. 相似文献
3.
Triblock cooligomers consisting of tri-O-methyl-glucopyranosyl and unmodified glucopyranosyl residues, methyl 2,3,4,6-tetra-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-α-d-glucopyranoside (1: ABA triblock cooligomer; DS = 2.1) and β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-d-glucopyranose (2: BAB triblock cooligomer; DS = 1.8) were prepared. Compound 1 dissolved both in distilled water and chloroform but compound 2 dissolved in distilled water not in chloroform, though compounds 1 and 2 consist of 4 tri-O-methyl-glucopyranosyl and 2 unmodified anhydro glucopyranosyl units. 相似文献
4.
Hiroshi Kamitakahara Kaoru Murata-Hirai Yoshimasa Tanaka 《Cellulose (London, England)》2012,19(1):171-187
Bioimaging is a key to understanding immune responses, cell differentiation, and development. Quantum dots (QDs) conjugated
with monoclonal antibodies and other biomolecules are currently utilized for flow cytometry and immunohistochemistry, but
monoclonal antibody–QD complexes are of limited use when cell surface markers are not available. In this study, we synthesized
novel amphiphilic blockwise alkylated tetrasaccharides and developed a simple method for labeling a wide variety of live cells
with organic QDs encapsulated with these carbohydrates. The novel amphiphilic blockwise alkylated tetrasaccharides were as
follows: methyl β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-d-glucopyranoside (1), methyl β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-methyl-d-glucopyranoside (2), ethyl β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-d-glucopyranoside, (3), and ethyl β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-β-d-glucopyranosyl-(1 → 4)-2,3,6-tri-O-ethyl-d-glucopyranoside (4). The newly synthesized blockwise alkylated tetrasaccharides spontaneously assembled into micelle-like particles, in which
the hydrophobic moiety of the blockwise alkylated tetrasaccharides played an important role. They were less toxic to human
cells than octyl β-d-glucopyranoside, a commonly used amphiphilic glucoside. Flow cytometry and confocal laser scanning microscopy revealed that
the blockwise alkylated tetrasaccharide–organic QD complexes were stably attached to live cells. The affinity of compounds
1 and 2 to the live cell surface was slightly higher than that of compounds 3 and 4. Because the preparation of these carbohydrate–QD
complexes is simple and does not require sophisticated equipment, and because the complexes can be autonomously attached to
a wide spectrum of cell lines, they can be used as cell labeling reagents in biomedical studies. 相似文献
5.
Two new polyhydroxysteroids and five new glycosides were isolated from the starfishCeramaster patagonicus and their structures were elucidated: 5α-cholestane-3β,6α,15β,16β,26-pentol, (22E)-5α-cholest-22-ene-3β,6α,8,15α,24-pentol, (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β,4β, 6α,8,15β,16β,28-heptol (ceramasteroside C1), (22E)-28-O-[O-(2,4-di-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β, 6α,8,15β,16β,28-hexol (ceramasteroside C2), (22E)-28-O-[O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β,6α,8,15β,16β 28-hexol (eramasteroside C3), (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-methyl-5α-cholest-22-ene-3β,4β,6α,8, 15β, 26-hexol (ceramasteroside C4), and (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-xylopyranosyl]-5α-cholest-22-ene-3β,6α,8,15β,24-pentol (ceramasteroside C5)). Three known polyhydroxysteroids (24-methylene-5α-cholestane-3β,6α,8,15β,16β,26-hexol, 5α-cholestane-3β,6α,8,15β,16β,26-hexol,
and 5α-cholestane-3β,6β,15α,16β,26-pentol) were also isolated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 190–195, January, 1997. 相似文献
6.
Jordan DB 《Applied biochemistry and biotechnology》2008,146(1-3):137-149
Catalytically efficient β-d-xylosidase from Selenomonas ruminantium (SXA) exhibits pK
as 5 and 7 (assigned to catalytic base, D14, and catalytic acid, E186) for k
cat/K
m with substrates 1,4-β-d-xylobiose (X2) and 1,4-β-d-xylotriose (X3). Catalytically inactive, dianionic SXA (D14−E186−) has threefold lower affinity than catalytically active, monoanionic SXA (D14−E186H) for X2 and X3, whereas D14−E186− has twofold higher affinity than D14−E186H for 4-nitrophenyl-β-d-xylopyranoside (4NPX), and D14−E186− has no affinity for 4-nitrophenyl-α-l-arabinofuranoside. Anomeric isomers, α-d-xylose and β-d-xylose, have similar affinity for SXA. 4-Nitrophenol competitively inhibits SXA-catalyzed hydrolysis of 4NPX. SXA steady-state
kinetic parameters account for complete progress curves of SXA-catalyzed hydrolysis reactions.
The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of
Agriculture over other firms or similar products not mentioned. 相似文献
7.
E. V. Sukhova A. V. Dubrovskii Yu. E. Tsvetkov N. E. Nifantiev 《Russian Chemical Bulletin》2007,56(8):1655-1670
2-Aminoethyl 3,6-di-O-sulfo-β-D-glucopyranosyl-(1→3)-β-D-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside, which is the sulfo-mimetic of the antigenic trisaccharide HNK-1, and the corresponding monosulfates, viz., 2-aminoethyl 3-O-sulfo-and 2-aminoethyl 6-O-sulfo-β-D-glucopyranosyl-(1→3)-β-D-galactopyranosyl-(1→ 4)-2-acetamido-2-deoxy-β-D-glucopyranosides, were synthesized. 2-Azidoethyl 2,4-di-O-benzoyl-β-D-glucopyranosyl-(1→3)-2,4,6-tri-O-benzoyl-β-D-galactopyranosyl-(1→ 4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside served as the common precursor for the sulfated trisaccharides. This compound was synthesized according to
the [2+1] pattern from monosaccharidic precursors: 3,6-di-O-acetyl-2,4-di-O-benzoyl-D-glucopyranosyl trichloroacetimidate, allyl 2-O-benzoyl-4,6-O-benzylidene-β-D-galactopyranoside, and 2-azidoethyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside. The structures of the glycosyl donors and glycosylation conditions were optimized for the efficient synthesis
of the glucosyl-β-(1→3)-galactose disaccharide block and its subsequent transformation into the target trisaccharide sequence.
Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1593–1607, August, 2007. 相似文献
8.
A simple one-step synthesis of β-d-galactopyranosyl azide from 0-nitrophenyl-β-d-galactopyranoside and azide catalyzed by E461G-β-galactosidase is described. The synthesis is quantitative in the presence
of excess azide and only the β anomer is produced. The product was purified (71% yield) from the other reaction components
by extraction with ethyl acetate, silica gel chromatography, and crystallization. The purity was verified by GLC, TLC, and
NMR. Thus, E461G-β-galactosidase is able to specifically and quantitatively from β-d-galactopyranosyl-azide. The purified β-d-galactopyranosylazide inhibited the growth of Escherichia coli that express β-galactosidase but not of E. coli that do not. Growth is stopped because β-galactosidase catalyzes the hydrolysis of the β-galactopyranosyl-azide, and the
azide that is produced inhibits cell growth. This selective inhibition of growth has potential application in molecular biology
screening. 相似文献
9.
The work presented herein is a new noncovalent glycoarray assembly method for microplates created by simply mixing together
a carbohydrate and a teradecylamine. α-d-Mannopyranoside, α-d-glucopyranoside, and α-d-galactopyranoside were utilized in model studies and product formations were detected by lectin binding. The method can be
extended to study the steric hindrance effect of carbohydrate-protein interactions, namely the structure-function relations
of carbohydrates.
These authors contributed equally to this work. 相似文献
10.
Mixtures of diblock co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides have been found to be amphiphilic, as reported before. In order to clarify
their accurate amphiphilic property, diblock co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides with monodispersity, methyl β-d-glucopyranosyl-(1→4)-2,3,6–tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6–tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-d-glucopyranoside (1, pentamer), methyl β-d-glucopyranosyl-(1→4)- β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-d-glucopyranoside (2, hexamer), and methyl β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-β-d-glucopyranosyl-(1→4)- 2,3,6-tri-O-methyl-d-glucopyranoside (3, trimer) were synthesized independently. These compounds had higher surface activities compared to the mixture of diblock
co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides and commercially available methylcellulose (MC) SM-4. This paper describes
the methods of synthesis of these compounds, and the influence of amphiphilic character on their surface activity. A new class
of carbohydrate-based nonionic surfactant without long alkyl chain was discovered. 相似文献