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P Albersheim

Publications and source records attributed to P Albersheim.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of seven xyloglucan oligosaccharides containing from seventeen to twenty glycosyl residues.

The complete primary structures of seven oligosaccharide subunits of the xyloglucan secreted by suspension-cultured Acer pseudoplatanus cells were determined. The oligosaccharides, ranging in size from 17 to 20 glycosyl residues, were generated by treatment of the xyloglucan with an endo-beta-(1----4)-glucanase. The oligosaccharide components of a fraction obtained by Bio-Gel P-2 chromatography of enzyme-treated xyloglucan were further purified by normal-phase h.p.l.c. and then converted to the corresponding oligoglycosyl alditols by reduction with NaBH4. The oligoglycosyl alditols, after purification to near homogeneity by reversed-phase h.p.l.c., were structurally characterized by 1H-n.m.r. spectroscopy, fast-atom bombardment mass spectrometry (f.a.b.-m.s.), and analysis of their glycosyl-residue and glycosyl-linkage compositions. Novel structural elements of xyloglucans were observed in this study, including beta-D-xylopyranosyl and alpha-L-arabinofuranosyl-(1----3)-beta-D-xylopyranosyl sidechains. The results also extend our list of correlations between 1H-n.m.r. resonances and specific structural features of xyloglucans and thus enhance our ability to determine the structures of xyloglucans from various sources.

Carbohydrate Sequence↗
PubMed1992

Evidence that the acidic polysaccharide secreted by Agrobacterium radiobacter (ATCC 53271) has a seventeen glycosyl-residue repeating unit.

The extracellular anionic polysaccharide produced by the bacterium Agrobacterium radiobacter (ATCC 53271) contains D-galactose, D-glucose, and pyruvic acid in the molar ratio 2:15:2. Analysis of the methylated polysaccharide indicated the presence of terminal, non-reducing glucosyl, 3-, 4-, 6-, 2,4-, and 4,6-linked glucosyl residues, 3-linked 4,6-O-[(S)-1-carboxyethylidene]glucosyl residues, and 3-linked galactosyl residues. Partial acid hydrolysis of the methylated polysaccharide, followed by reduction with NaB2H4 and then O-ethylation, gave a mixture of alkylated oligoglycosyl alditols that were separated by reversed-phase h.p.l.c. and analyzed by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. Smith degradation of the polysaccharide gave three diglycosyl alditols that were separated by semi-preparative, high-pH anion-exchange chromatography, and were analyzed by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. The polymer obtained by NaBH4 reduction of the periodate-oxidized polysaccharide was methylated, and the noncyclic acetals were hydrolyzed with aq. 90% formic acid to generate a mixture of partially O-methylated mono- and di-glycosyl alditols. The partially O-methylated oligoglycosyl alditols were O-ethylated. The resulting alkylated oligoglycosyl alditols were separated by reverse-phase h.p.l.c. and then characterized by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. The results from the studies described here provide strong evidence that the acidic polysaccharide secreted by A. radiobacter (ATCC 53271) has a heptadecasaccharide repeating unit.

Carbohydrate Sequence↗
PubMed1992

CarbBank.

Explore the source record for details and available documents.

Carbohydrate Sequence↗
PubMed1991

Structural characterization of two oligosaccharide fragments formed by the selective cleavage of rhamnogalacturonan II: evidence for the anomeric configuration and attachment sites of apiose and 3-deoxy-2-heptulosaric acid.

Evidence for the anomeric configurations and attachment sites of 3-deoxy-D-lyxo-2-heptulosaric acid (DHA) and apiosyl residues has been obtained through the characterization of two oligoglycosyl fragments isolated from rhamnogalacturonan II (RG-II). One of the oligoglycosyl fragments, a pentaglycosyl aldonic acid generated by Smith degradation of RG-II, was composed of four D-galactopyranosyluronic acid residues, a DHA residue, and a threonic acid residue (derived from a D-galactopyranosyluronic acid residue). The structural analysis of the pentaglycosyl aldonic acid established the beta-D-configuration for the DHA residue. Furthermore, it established that a previously identified diglycosyl side chain, 5-O-(beta-L-arabinofuranosyl)-DHA was directly attached to O-3 of a D-galactopyranosyluronic acid residue in the backbone of RG-II. The second oligoglycosyl fragment, a peralkylated diglycosyl hex-1-enitol, was generated by hex-5-enose degradation of permethylated and carboxyl-reduced RG-II. The structure of the peralkylated diglycosyl hex-1-enitol, beta-L-Rhap-(1----3')-beta-D-Apif-(1----5)-hex-1-enitol++ +, was determined by a combination of glycosyl-linkage composition analysis and n.m.r. spectroscopy. The n.m.r. data indicated the beta-configuration for the D-apiosyl residue. The isolation and characterization of the diglycosyl hex-1-enitol also established that a previously identified heptaglycosyl side chain was directly attached to O-2 of a D-galactopyranosyluronic acid in the backbone of RG-II.

Butyrates↗
PubMed1991

The degree of esterification and points of substitution by O-acetyl and O-(3-hydroxybutanoyl) groups in the acidic extracellular polysaccharides secreted by Rhizobium leguminosarum biovars viciae, trifolii, and phaseoli are not related to host range.

Rhizobium leguminosarum biovars viciae, trifolii, and phaseoli have been grown in the presence and absence of 4',5,7-trihydroxyflavonone (naringenin) or 4',5,7-trihydroxyflavone (apigenin), which induce the expression of nodulation genes of the bacteria. The acidic polysaccharides secreted by the Rhizobium were isolated from the culture media and purified. The polysaccharides were cleaved with a bacteriophage enzyme and the octasaccharide repeating units formed were isolated. The glycosyl sequence and type of nonglycosyl substituents of the repeating units derived from a number of these Rhizobium biovars were shown by fast atom bombardment-mass spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR) to be identical. Minor variations in the degree of esterification of the repeating units by O-acetyl and O-(3-hydroxybutanoyl) substituents were observed when the Rhizobium were grown in the presence or absence of the flavonoids. The variation in content and the points of attachment of the O-acetyl and O-(3-hydroxybutanoyl) substituents were as great within each Rhizobium biovar as between different Rhizobium biovars and, contrary to two recent reports (Philip-Hollingsworth, S., Hollingsworth, R. I., and Dazzo, F. B. (1989) J. Biol. Chem. 264, 1461-1466; Philip-Hollingsworth, S., Hollingsworth, R. I., Dazzo, F. B., Djordjevic, M. A., and Rolfe, B. G. (1989) J. Biol. Chem. 264, 5710-5714), the O-acylation patterns were not correlated with the host specificity of the bacteria.

Acetylation↗
PubMed1991

A new undecasaccharide subunit of xyloglucans with two alpha-L-fucosyl residues.

A new oligosaccharide subunit of xyloglucan was isolated from the beta-(1----4)-endoglucanase digestion products of the xyloglucan in what is referred to as "sycamore extracellular polysaccharides" and found to be an undecasaccharide having two terminal alpha-L-fucopyranosyl residues. The undecasaccharide was structurally characterized by 1H-n.m.r. spectroscopy, fast-atom bombardment mass spectrometry (f.a.b.-m.s.), and glycosyl-residue and glycosyl-linkage composition analyses. The structure of the undecasaccharide was confirmed by digesting it with a hydrolase that releases alpha-D-Xylp-(1----6)-D-Glc from the non-reducing end of xyloglucan oligosaccharides.

Acylation↗
PubMed1991

Identification of the 1H-NMR spectra of complex oligosaccharides with artificial neural networks.

Artificial networks can be used to identify hydrogen nuclear magnetic resonance (1H-NMR) spectra of complex oligosaccharides. Feed-forward neural networks with back-propagation of errors can distinguish between spectra of oligosaccharides that differ by only one glycosyl residue in twenty. The artificial neural networks use features of the strongly overlapping region of the spectra (hump region) as well as features of the resolved regions of the spectra (structural reporter groups) to recognize spectra and efficiently recognized 1H-NMR spectra even when the spectra were perturbed by minor variations in their chemical shifts. Identification of spectra by neural network-based pattern recognition techniques required less than 0.1 second. It is anticipated that artificial neural networks can be used to identify the structures of any complex carbohydrate that has been previously characterized and for which a 1H-NMR spectrum is available.

Artificial Intelligence↗
PubMed1990

Structural analysis of an acidic polysaccharide secreted by Xanthobacter sp. (ATCC 53272).

The structure of an acidic polysaccharide secreted by a Xanthobacter sp. has been investigated by glycosyl-residue and glycosyl-linkage composition analyses, and the characterization of oligoglycosyl fragments of the polysaccharide has been carried out by chemical analyses, 1H-n.m.r. spectroscopy, fast-atom bombardment mass spectrometry, and electron-impact mass spectrometry. The polysaccharide, which contains O-acetyl groups (approximately 5%) that have not been located, has the tetraglycosyl repeating unit 1 and belongs to a group of structurally related polysaccharides synthesized by both Alcaligenes and Pseudomonas species.

Carbohydrate Conformation↗
PubMed1990

Structural analysis of xyloglucan oligosaccharides by 1H-n.m.r. spectroscopy and fast-atom-bombardment mass spectrometry.

A method to determine rapidly the identities and proportions of the oligosaccharide repeating-units in plant cell-wall xyloglucans by 1D 1H-n.m.r. spectroscopy was developed. Six of the most commonly found xyloglucan oligosaccharide subunits (including three subunits that had not been fully characterized previously) were prepared by endo-(1----4)-beta-D-glucanase digestion of xyloglucans from various plant species. The oligosaccharides were reduced to the corresponding oligoglycosyl-alditols, purified, and characterized by glycosyl composition and linkage analysis, 1H-n.m.r. spectroscopy, and f.a.b.-mass spectrometry. Correlations between the 1H-n.m.r. spectra and the structures of the oligoglycosyl-alditols can be used to identify oligoglycosyl-alditols derived from xyloglucans of unknown structure. The identities and relative amounts of the oligosaccharide subunits of xyloglucans isolated from tamarind seed and rapeseed hulls were determined on this basis.

Carbohydrate Conformation↗
PubMed1990

The control of root, vegetative shoot and flower morphogenesis in tobacco thin cell-layer explants (TCLs).

Thin cell-layer explants (TCLs) have been proposed as favorable tissues for the study of root, vegetative shoot and flower formation. We tested the effects of pH, light quality, light quantity, and IBA and kinetin concentrations on the morphogenesis of TCLs cultured individually on a liquid medium. Alterations of the amounts of exogenously supplied IBA and kinetin were sufficient to induce the formation of roots, vegetative shoots and flowers on TCLs cultured on otherwise identical media. The type and number of organs formed were sensitive to the intensity of light (55, 75, 100 and 120 muEinsteins m-2 sec-1) under which TCLs were grown. Evidence was obtained that the effects of light on TCL morphogenesis were associated with photochemical degradation of IBA in the medium. Evaluation of the organogenesis that occurred in TCLs cultured on a medium containing a range of IBA and kinetin concentrations showed that the number and type of organs formed, and overall growth, were dependent upon the initial concentrations of auxin and cytokinin. We have developed the TCL culture system into a sensitive and reproducible bioassay for the study of morphogenesis. The advantages of using the TCL morphogenesis bioassay for the identification and study of molecules (e.g. cell wall oligosaccharides) that may regulate morphogenesis are discussed.

Adenine↗
PubMed1989

Purification and characterization of a xyloglucan oligosaccharide-specific xylosidase from pea seedlings.

An alpha-xylosidase that acts on oligosaccharide fragments of xyloglucan, a plant cell wall polysaccharide, was purified from pea (Pisum sativum) epicotyls that had been treated with an auxin analog. The enzyme had an apparent molecular mass of 85,000 Da according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 79,000 Da according to gel-permeation chromatography under nondenaturing conditions. The purified xylosidase consisted of a series of closely related, enzymatically active proteins with isoelectric points ranging from about pH 7.35 to 7.7; the xylosidases were separated by chromatofocusing. The pH optimum of the mixed xylosidase was 4.9-5.1. The substrate specificity of the xylosidase mixture was determined by purification and structural characterization of the products of treating xyloglucan-oligosaccharide substrates with the enzyme. Characterization of the substrates and products included elution volume from a gel-permeation column, glycosyl residue and glycosyl linkage composition analyses, fast atom bombardment-mass spectrometry, and 1H NMR spectroscopy. The enzyme specifically cleaved only one of the alpha-xylosidic linkages of xyloglucan-oligosaccharide substrates, the one attached to a 6-linked glucosyl residue, not those attached to the 4,6-linked glucosyl residues. The enzyme was unable to cleave the xylosidic linkage of p-nitrophenyl-alpha-D-xylopyranoside or the alpha-xylosidic linkage to C-6 of glucose in the disaccharide isoprimeverose. The enzyme was also unable to release measurable amounts of xylose from large xyloglucan polymers.

Carbohydrate Conformation↗
PubMed1989

A fluorescence assay for enzymes that cleave glycosidic linkages to produce reducing sugars.

A rapid, facile, and sensitive assay has been developed for enzymes that generate reducing sugars. The assay is a modification of a method for post-HPLC column derivatization and detection of reducing sugars and is carried out in a single test tube. The assay is useful for large numbers of samples, such as those produced during purification of enzymes. Less than 500 pmol of reducing sugar can be quantitatively measured. The assay reported here is at least 10 times more sensitive than either the commonly employed parahydroxybenzoic acid hydrazide method or the recently reported bicinchoninate method, and 50 times more sensitive than the Nelson-Somogyi method.

Carbohydrates↗
PubMed1989

The Complex Carbohydrate Structure Database.

The Complex Carbohydrate Structure Database (CCSD) and CarbBank, an IBM PC/AT (or compatible) database management system, were created to provide an information system to meet the needs of people interested in carbohydrate science. The CCSD, which presently contains more than 2000 citations, is expected to double in size in the next two years and to include, soon thereafter, all of the published structures of carbohydrates larger than disaccharides.

Carbohydrates↗
PubMed1988

Location of the O-acetyl substituents on a nonasaccharide repeating unit of sycamore extracellular xyloglucan.

The locations of the O-acetyl substituents on the major nonasaccharide repeating unit of the xyloglucan isolated from sycamore extracellular polysaccharides were determined by a combination of analytical methods, including f.a.b.-m.s. and 1H-n.m.r. spectroscopy. The O-2-linked-beta-D-galactosyl residue of the nonasaccharide was found to be the dominant site of O-acetyl substitution. Both mono-O-acetylated and di-O-acetylated beta-D-galactosyl residues were detected. The degree of O-acetylation of the beta-D-galactosyl residue, was estimated by 1H-n.m.r. spectroscopy to be 55-60% at O-6, 15-20% at O-4, and 20-25% at O-3. 1H-n.m.r. spectroscopy also indicated that approximately 50% of the beta-D-galactosyl residues are mono-O-acetylated, 25-30% are di-O-acetylated, and 20% are not acetylated.

Carbohydrate Conformation↗
PubMed1985

Structure and function of plant cell wall polysaccharides.

Studies of the primary structures of polysaccharides of growing plant cell walls have shown that these structures are far more complex than was anticipated just a few years ago. This complexity can best be appreciated by considering xyloglucan, a hemicellulose present in the cell wall of both monocots and dicots, and rhamnogalacturonan II (RG-II) and rhamnogalacturonan I (RG-I), two structurally unrelated pectic polysaccharides. This realization led us to postulate that cell wall polysaccharides have functions beyond determining the size, shape and strength of plants. Some years ago we demonstrated that oligosaccharide fragments of a branched beta-linked glucan of fungal cell walls can elicit the production of phytoalexins (antibiotics) in plants by inducing the formation of the enzymes responsible for synthesis of the phytoalexins. It has now been ascertained and confirmed by synthesis that the elicitor activity resides in a very specific hepta-beta-D-glucoside. The heptaglucoside has been shown to elicit phytoalexins by activating the expression of specific genes, that is, by causing the synthesis of the mRNAs that encode the enzymes that synthesize phytoalexins. In other words, complex carbohydrates can be regulatory molecules. Further experiments established that oligosaccharide fragments of polysaccharides, produced by acid or base hydrolysis or by enzymolysis of primary cell walls of plants, also evoked defence responses in plants. Subsequently, we learned that defined fragments of polysaccharides, released from covalent attachment within plant cell walls, can function as regulators of various physiological processes such as morphogenesis, rate of cell growth and time of flowering and rooting, in addition to activating mechanisms for resisting potential pathogens. Examples of plant oligosaccharides with regulatory properties (called oligosaccharins) will be described.

Cell Survival↗
PubMed1978

Some phytotoxic glycopeptides from Ceratocystis ulmi, the Dutch Elm Disease pathogen.

Ceratocystis ulmi, the causal agent of Dutch Elm Disease, produces phytotoxic glycopeptides in culture. A mixture of phytotoxic glycopeptides has been prepared by affinity chromatography on a concanavalin A-Sepharose column and collectively they have been termed the toxin. The polydisperse component that makes up the majority of toxin (80%) by weight has a molecular weight of about 2.7.10(5). The large molecular weight component (less than 5%) elutes at the void volume of a Bio-Gel A 50 m column. The other component (15%) appears as a trailing peak on the edge of the major component and has an approximate molecular weight of 7.10(4). The toxin is composed of 83% sugar residues, primarily rhamnose and mannose, and 7% amino acid residues. Methylation analysis coupled with mild acid hydrolysis indicates that the backbone of the polysaccharide portion of the toxin is composed of alpha -1,6-linked mannosyl residues with a 3-linked terminal rhamnosyl residue linked to C-3 of almost every mannosyl residue. The carbohydrate portion of the molecule is linked to the peptide via O-glycosidic linkages to both threonyl and seryl residues. All three components of the toxin are capable of causing wilt in stem cuttings of American elm.

Amino Acids↗