THE CONSTITUTION OF THE HEMICELLULOSE OF APPLE WOOD (MALUS PUMILA L. VAR. GOLDEN TRANSPARENT)

1961 ◽  
Vol 39 (10) ◽  
pp. 1995-2000 ◽  
Author(s):  
G. G. S. Dutton ◽  
T. G. Murata
Keyword(s):  
Glucuronic Acid ◽  
Single Units ◽  
Alkaline Extraction ◽  
Methylation Data ◽  
Malus Pumila ◽  
Hydrolysis Products

The hemicellulose isolated by direct alkaline extraction of the wood has been shown to be a 4-O-methylglucuronoxylan. Methylation data indicate a backbone of approximately 120 D-xylopyranose units linked by β, 1—4 bonds with single units of 4-O-methyl-D-glucuronic acid linked by α, 1—2 bonds. The proportion of acid units to xylose is approximately 1:6. Two artifacts were isolated from the hydrolysis products of the methylated polysaccharide: 4-O-(2,3-di-O-methyl-α-D-xylopyranosyl)-2,3-di-O-methyl-D-xylose and 2,3-di-O-methyl-D-lyxose.

THE CONSTITUTION OF A HEMICELLULOSE OF CHERRY WOOD (PRUNUS AVIUM L. VAR. BING)

1961 ◽  
Vol 39 (12) ◽  
pp. 2582-2589 ◽  
Author(s):  
G. G. S. Dutton ◽  
Shirley A. McKelvey
Keyword(s):  
Prunus Avium ◽  
Glucuronic Acid ◽  
Single Units ◽  
Alkaline Extraction ◽  
Methylation Data ◽  
Prunus Avium L

The hemicellulose isolated by direct alkaline extraction of the wood has been shown to be a 4-O-methyl-D-glucuronoxylan. Methylation data indicate a backbone of approximately 110 D-xylopyranose units linked by β, 1 → 4 bonds with single units of 4-O-methyl-D-glucuronic acid linked by α, 1 → 2 bonds. The proportion of acid units to xylose is approximately 1:7. 2,3-Di-O-methyl-D-lyxose was isolated as an artifact.

Polysaccharides of tropical pasture herbage. II. A xylan from the leaf of spear grass (Heteropogon contortus)

1970 ◽  
Vol 23 (11) ◽  
pp. 2361 ◽  
Author(s):  
JD Blake ◽  
GN Richards
Keyword(s):  
Gas Chromatography ◽  
Acid Hydrolysis ◽  
Copper Complex ◽  
Glucuronic Acid ◽  
Single Units ◽  
Alkaline Extraction ◽  
Tropical Pasture ◽  
Fractional Precipitation ◽  
Heteropogon Contortus ◽  
Hydrolysis Of

Alkaline extraction of spear grass holocellulose gave a xylan which was purified by fractional precipitation as a copper complex. Acid hydrolysis yielded L-arabinose, D-xylose, and an aldobiouronic acid consisting of D-xylose and 4-O-methyl-D-glucuronic acid. Hydrolysis of the methylated xylan gave 2,3,5-tri-O-methyl-L- arabinose, 2,3,4-tri-, 2,3-di-, and 2-O-methyl-D-xylose, and 3-O-methyl-2-O-(2,3,4-tri-O-methyl-D-glucopyranosyluronic acid)-D-xylose. The conditions for isolation of the methylated sugars for gas chromatography were investigated with particular reference to difficulties arising from volatility of the tri-O-methyl pentoses. The xylan is composed of chains of 1,4-linked �-D-xylopyranose residues to which are attached single units of L-arabinofuranose at position 3 and 4-O-methyl-D-glucuronic acid at position 2 of the basal residues.

The Fate of 4-O-Methyl Glucuronic Acid in Hardwood Xylan during Alkaline Extraction

2017 ◽  
Vol 5 (2) ◽  
pp. 1818-1823 ◽  
Author(s):  
Christian Hutterer ◽  
Karin Fackler ◽  
Antje Potthast
Keyword(s):  
Glucuronic Acid ◽  
Alkaline Extraction

scholarly journals GH30 Glucuronoxylan-Specific Xylanase fromStreptomyces turgidiscabiesC56

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Tomoko Maehara ◽  
Haruka Yagi ◽  
Tomoko Sato ◽  
Mayumi Ohnishi-Kameyama ◽  
Zui Fujimoto ◽  
...  
Keyword(s):  
Main Chain ◽  
Glucuronic Acid ◽  
Substrate Recognition ◽  
Side Chain ◽  
Glycoside Hydrolase Family ◽  
Content Type ◽  
Hydrolysis Products ◽  
Streptomyces Turgidiscabies ◽  
Definition Of ◽  
Hydrolase Family

ABSTRACTEndoxylanases are important enzymes in bioenergy research because they specifically hydrolyze xylan, the predominant polysaccharide in the hemicellulose fraction of lignocellulosic biomass. For effective biomass utilization, it is important to understand the mechanism of substrate recognition by these enzymes. Recent studies have shown that the substrate specificities of bacterial and fungal endoxylanases classified into glycoside hydrolase family 30 (GH30) were quite different. While the functional differences have been described, the mechanism of substrate recognition is still unknown. Therefore, a gene encoding a putative GH30 endoxylanase was cloned fromStreptomyces turgidiscabiesC56, and the recombinant enzyme was purified and characterized. GH30 glucuronoxylan-specific xylanase A ofStreptomyces turgidiscabies(StXyn30A) showed hydrolytic activity with xylans containing both glucuronic acid and the more common 4-O-methyl-glucuronic acid side-chain substitutions but not on linear xylooligosaccharides, suggesting that this enzyme requires the recognition of glucuronic acid side chains for hydrolysis. TheStXyn30A limit product structure was analyzed following a secondary β-xylosidase treatment by thin-layer chromatography and mass spectrometry analysis. The hydrolysis products from both glucuronoxylan and 4-O-methylglucuronoxylan byStXyn30A have these main-chain substitutions on the second xylopyranosyl residue from the reducing end. Because previous structural studies of bacterial GH30 enzymes and molecular modeling ofStXyn30A suggested that a conserved arginine residue (Arg296) interacts with the glucuronic acid side-chain carboxyl group, we focused on this residue, which is conserved at subsite −2 of bacterial but not fungal GH30 endoxylanases. To help gain an understanding of the mechanism of howStXyn30A recognizes glucuronic acid substitutions, Arg296 mutant enzymes were studied. The glucuronoxylan hydrolytic activities of Arg296 mutants were significantly reduced in comparison to those of the wild-type enzyme. Furthermore, limit products other than aldotriouronic acid were observed for these Arg296 mutants upon secondary β-xylosidase treatment. These results indicate that a disruption of the highly conserved Arg296 interaction leads to a decrease of functional specificity inStXyn30A, as indicated by the detection of alternative hydrolysis products. Our studies allow a better understanding of the mechanism of glucuronoxylan recognition and enzyme specificity by bacterial GH30 endoxylanases and provide further definition of these unique enzymes for their potential application in industry.IMPORTANCEHemicellulases are important enzymes that hydrolyze hemicellulosic polysaccharides to smaller sugars for eventual microbial assimilation and metabolism. These hemicellulases include endoxylanases that cleave the β-1,4-xylose main chain of xylan, the predominant form of hemicellulose in lignocellulosic biomass. Endoxylanases play an important role in the utilization of plant biomass because in addition to their general utility in xylan degradation, they can also be used to create defined compositions of xylooligosaccharides. For this, it is important to understand the mechanism of substrate recognition. Recent studies have shown that the substrate specificities of bacterial and fungal endoxylanases that are classified into glycoside hydrolase family 30 (GH30) were distinct, but the difference in the mechanisms of substrate recognition is still unknown. We performed characterization and mutagenesis analyses of a new bacterial GH30 endoxylanase for comparison with previously reported fungal GH30 endoxylanases. Our study results in a better understanding of the mechanism of substrate specificity and recognition for bacterial GH30 endoxylanases. The experimental approach and resulting data support the conclusions and provide further definition of the structure and function of GH30 endoxylanases for their application in bioenergy research.

CONSTITUTION OF A POLYURONIDE HEMICELLULOSE FROM WHEAT LEAF

1954 ◽  
Vol 32 (2) ◽  
pp. 186-194 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Uronic Acid ◽  
Glucuronic Acid ◽  
Periodate Oxidation ◽  
Reducing Power ◽  
Degree Of Polymerization ◽  
Acid Anhydride ◽  
Alkaline Extraction ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Acid Unit

Crude hemicellulose of mature wheat leaves has been prepared by alkaline extraction of leaf holocellulose. Purification by repeated complexing with Fehling′s solution yielded a polyuronide hemicellulose [Formula: see text] composed of D-xylose (88.5%), L-arabinose (6.90%), and uronic acid anhydride (5.27%). Methylation studies indicated a molecular structure comprising a main xylan chain of 30 an-hydro- D-xylose residues to which three L-arabinose residues and one D-glucuronic acid unit were attached as side chains by glycosidic linkages. Periodate oxidation data supported the proposed structure and the yield of formic acid indicated a molecule containing approximately 32 sugar residues. Estimations of the degree of polymerization of the molecule by measurements of viscosity and reducing power agreed with the foregoing values. The structure of the hemicellulose closely resembled that of one isolated previously from wheat straw.

scholarly journals A New Subfamily of Glycoside Hydrolase Family 30 with Strict Xylobiohydrolase Function

2021 ◽  
Vol 8 ◽  
Author(s):  
Casey Crooks ◽  
Nathan J. Bechle ◽  
Franz J. St John
Keyword(s):  
Glycoside Hydrolase ◽  
Glucuronic Acid ◽  
Commercial Production ◽  
Glycoside Hydrolase Family ◽  
Biophysical Parameters ◽  
Reaction Conditions ◽  
Hydrolysis Products ◽  
Clostridium Clariflavum ◽  
Hydrolase Family ◽  
Glycoside Hydrolase Family 30

The Acetivibrioclariflavus (basonym: Clostridium clariflavum) glycoside hydrolase family 30 cellulosomal protein encoded by the Clocl_1795 gene was highly represented during growth on cellulosic substrates. In this report, the recombinantly expressed protein has been characterized and shown to be a non-reducing terminal (NRT)-specific xylobiohydrolase (AcXbh30A). Biochemical function, optimal biophysical parameters, and phylogeny were investigated. The findings indicate that AcXbh30A strictly cleaves xylobiose from the NRT up until an α-1,2-linked glucuronic acid (GA)-decorated xylose if the number of xyloses is even or otherwise a single xylose will remain resulting in a penultimate GA-substituted xylose. Unlike recently reported xylobiohydrolases, AcXbh30A has no other detectable hydrolysis products under our optimized reaction conditions. Sequence analysis indicates that AcXbh30A represents a new GH30 subfamily. This new xylobiohydrolase may be useful for commercial production of industrial quantities of xylobiose.

THE CONSTITUTION OF A METHYL GLUCURONOXYLAN FROM KAPOK (CEIBA PENTANDRA)

1959 ◽  
Vol 37 (5) ◽  
pp. 922-929 ◽  
Author(s):  
A. L. Currie ◽  
T. E. Timell
Keyword(s):  
Galacturonic Acid ◽  
Uronic Acid ◽  
Glucuronic Acid ◽  
Molar Ratio ◽  
Side Chain ◽  
Partial Hydrolysis ◽  
Alkaline Extraction ◽  
Branching Points ◽  
Seed Hairs ◽  
Hydrolysis Of

The seed hairs of kapok (Ceibapentandra) on alkaline extraction have yielded a hemicellulose composed of xylose and uronic acid residues. Partial hydrolysis of the polysaccharide gave 2-O-(4-O-methyl-α-D-glucopyranosyluronic acid)-D-xylopyranose, 4-O-methyl-D-glucuronic acid, and, probably, galacturonic acid. Hydrolysis of the fully methylated hemicellulose yielded a mixture of 2-O- and 3-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and 2-O-(2,3,4-tri-O-methyl-α-D-glucopyranosyluronic acid)-3-O-methyl-D-xylopyranose in a molar ratio of 1.1:38:1:6. The number-average D.P. of the native and the methylated polysaccharides was 177 and 124, respectively. On the basis of this and other evidence it is suggested that the average hemicellulose molecule contains approximately 180 1,4-linked β-D-xylopyranose residues, one eighth of which carry a single terminal side chain of 4-O-methyl-D-glucuronic acid, attached through an α-glycosidic bond to C2 of the xylose. The xylan framework contains, on the average, slightly less than two branching points per macromolecule, most of them probably originating from C3. The number of acid side chains and branches is twice as large as that of the otherwise similar 4-O-methyl glucuronoxylan present in the seed hairs of milkweed floss.

CONSTITUTION OF AN ACIDIC XYLAN FROM TAMARACK (LARIX LARICINA)

1960 ◽  
Vol 38 (12) ◽  
pp. 2402-2409 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Molecular Weight ◽  
Uronic Acid ◽  
Glucuronic Acid ◽  
Periodate Oxidation ◽  
Degree Of Polymerization ◽  
Single Units ◽  
Larix Laricina ◽  
Glycosidic Bonds

An acidic xylan isolated from tamarack wood contained arabinose, xylose, and uronic acid (1:17:3) and was homogeneous on examination by electrophoresis and sedimentation. Molecular weight estimations by four different methods showed a degree of polymerization of 20. Methylation and periodate oxidation showed that the xylan consisted of ca. 16 β-D-xylopyranose units joined by 1 → 4 glycosidic bonds with the possible occurrence of one 1 → 3 linkage. To this unbranched structure were attached as side branches, three single units of 4-O-methyl-D-glucuronic acid through C2 and one unit of L-arabofuranose through C3.

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