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At least 19 recordsLinked to original sources
PubMed1975

Differential alkali-extraction of hemicellulose and hydroxyproline from non-delignified cell walls of lupin hypocotyls.

The extraction by alkali of hemicellulose polysaccharides and polymer hydroxyproline from non-delignified, primary cell-walls of lupin hypocotyls has been studied, using sequential extractions at 0 degrees and 18-22 degrees. 10% Aqueous potassium hydroxide at 0 degrees rapidly removed about two-thirds of the hemicellulose normally extracted in 10% KOH at 18-22 degrees and including nearly all of the hemicellulose-A. Little hydroxyproline was released at 0 degrees. When the temperature was subsequently raised to 18-22 degrees, the remaining 10% KOH-soluble hemicellulose, along with most of the hydroxyproline, was released. The monosaccharide composition of these fractions changed markedly with the time of extraction. Arabinose increased from 35% of the polysaccharide extracted during the first hour at 18-22 degrees to similar to 65% of the polysaccharide extracted between 16 and 20 h at 18-22 degrees. Hydroxyproline changed similarly as a proportion of polymer. The implications of these and other results are discussed in relation to polysaccharide and polymer extraction without prior delignification and to models of the primary cell-wall.

Arabinose↗
PubMed1978

Xylan-degrading activity in yeasts: growth on xylose, xylan and hemicelluloses.

The ability to grow in liquid media with D-xylose, xylan from decidous trees, and hemicelluloses from conifers was tested in 95 strains of 35 genera of yeasts and yeast-like organisms. Of 54 strains thriving on xylose, only 13 (genera Aureobasidium, Cryptococcus and Trichosporon) utilized xylan and hemicelluloses as growth substrates. The árowth media of these strains were found to contain xylan-degrading enzymes splitting the substrate to xylose and a mixture of xylose oligosaccharides. The ability of these yeasts to utilize the wood components (hitherto unknown in the genus Crytococcus) makes them potential producers of microbial proteins from industrial wood wastes containing xylose oligosaccharides, xylan, and hemicelluloses as the major saccharide components without previous saccharification.

Cell-Free System↗
PubMed1979

Growth of Aureobasidium pullulans on waste water hemicelluloses.

Strain Aureobasidium pullulans capable of utilizing hemicelluloses and xylan was cultivated on processed waste dialysis liquor from the production of viscose fibres, containing about 1.5% hemocelluloses. Basic conditions of biomass production were tested on a laboratory scale. The dialysis waste liquor adjusted with mineral acids to pH 4--5 and supplemented with 0.05% yeast autolyzate and 0.2% ammonium sulphate affords protein yields of about 0.8 g/l, corresponding to 4.0--4.5 g dry biomass. Biomass is isolated together with residual water-insoluble hemicelluloses which are not utilized by the microorganism. The total utilization of hemicelluloses attains about 70%.

Cellulose↗
PubMed1976

Influence of molasses lignin-hemicellulose fractions in rat nutrition.

Previous reports have shown that fractionation of the non-sugar, non-dialyzable components of cane molasses yielded a fraction designated as a black phenolic-carbohydrate complex. Incorporation of 0.03% of this complex into diets fed weanling male rats significantly increased the growth rate above that of rats fed the basal diet alone. This study was conducted to determine the chemical nature and growth stimulating action of the black phenol-carbohydrate complex. Alkaline cleavage under nitrogen yielded a mixture of phenols and a carbohydrate fraction which was recovered by precipitation at pH 6 in four volumes of ethanol. The alkaline cleaved, free hemicellulose was non-diayzable and stimulated growth when incorporated into rat diets at the 0.03% levels. Acid hydrolysis of the complex yielded an insoluble product identified as lignin and found to represent 18% to 20% of the entire complex. The chemical nature of this ligninhemicellulose fraction and the previously reported growth-enhancing acid resistant hemicellulose fraction isolated from various plant sources were found to be similar.

Animal Nutritional Physiological Phenomena↗
PubMed1976

Complete regression of Ehrlich solid tumors by the combined administration of glucose, wheat straw hemicellulose-B, and ovoglycopeptide.

Glucose solution containing wheat straw hemicellulose-B and ovoglycopeptide (W-O-G) has no effect on Ehrlich ascites tumors but completely regresses Ehrlich solid tumors. The carcinostatic effect of this mixture is lost or decreases markedly whenever one of the three substances is lacking. For this glucose solution to possess a carcinostatic effect it is necessary that this hemicellulose-B of W-O-G is the hydrolysate of the extract with 20% NaOH from the residue obtained after extraction of wheat straw with 10% NaOH.

Animals↗
PubMed2026

Trimming galactose side chains of arabinogalactan proteins alters pectin and hemicellulose deposition in secondary cell walls of Arabidopsis thaliana floral stem internodes.

Shaping the cell wall composition and structure to meet the requirements of different tissues and developmental stages relies on multiple actors, including arabinogalactan proteins (AGPs). Although the specific role of these proteins in cell wall dynamics is still under debate, especially in events involving significant remodeling of the cell wall, their carbohydrate motif, type II arabinogalactan (AGII), seems to be crucial for their function. This study aims to investigate the function of AGII, specifically the galactose residues of its side chains, in the structural organization of the cell wall during the cessation of elongation and the transition to secondary growth. To achieve this, we characterized floral stem internodes of Arabidopsis thaliana plants overproducing the chickpea βV-galactosidase protein (35S::βV-Gal plants), an enzyme that specifically hydrolyzes the β-(1,3)- and β-(1,6)-galactosyl residues of AGII. Changes induced in the cell wall by trimming galactose residues of AGII resulted in a noticeable increase in homogalacturonan methyl esterification. Additionally, these neutral galactose side chains may regulate hemicellulose-cellulose interactions and influence xylan distribution through the cellulose network, which in turn affects the deposition of lignin and determines its recalcitrance to enzymatic degradation.

Arabidopsis↗
PubMed1975

Structures of the oligosaccharides from the enzymic hydrolysis of hemicellulose by a hemicellulase of Ceratocystis paradoxa.

And endo-hemicellulase (HC-II) of Ceratocystis paradoxa degraded spear-grass hemicellulose B to a series of mixed oligosaccharides. Four neutral oligosaccharides (AraXyl2, AraXyl3, Xyl2, and Xyl3), isolated by preparative paper chromatography, were shown by enzymic and methylation techniques to constitute a series of beta-(1 leats to 4)-D-xylose and O-alpha-L-arabinofuranosyl-(1 leads to 3)-O-beta-D-xylopyranosyl-(1 leads to 4)-O-beta-D-xylopyranosyl-(1 leads to 4)-D-xylose, respectively, the latter being a new compound.

Ascomycota↗
PubMed1977

Changes in enzymic activities of nucleoside diphosphate sugar interconversions during differentiation of cambium to xylem in sycamore and poplar.

During the transition from primary wall formation to secondary thickening there is a marked shift in the synthesis of pectin, hemicellulose and cellulose. The activities of the enzymes [UDP-D-galactose 4-epimerase (EC 5.1.3.2)8 UDP-l-arabinose 4-epimerase (EC 5.1.3.5), UDP-D-glucose dehydrogenase (EC 1.1.1.22) and UDP-D--glucuronate decarboxylase (EC 4.1.1.35)] were measured in cambial cells, differentiating xylem cells and differentiated xylem cells isolated from sycamore and poplar trees, and phloem cells from poplar. At the final stage of the differentiation of cambium to xylem there was a decrease in activity of the enzymes directly involved in producing the soluble precursors of pectin (DUP-D-galactose 4-epimerase and UDP-L-arabinose 4-epimerase and an increase in those producing the precursors of hemicellulose (UDP-D-glucose dehydrogenase and UDP-D-glucuronate decarboxylase). These results strongly suggest ahat the changes were correlated with the differences observed in the chemical composition of the wall during development. The changes found in the catalytic activity of the enzymes of nucleoside diphosphate sugar interconversion exert a coarse control over the synthesis of pectin and hemicelluloses. The tissues at all stages of development contained the necessary enzyme activities to produce all the precursors of pectin and hemicellulose, even at the final stage of differentiation when no pectin was formed.

Arabinose↗
PubMed1978

Digestion of certain fractions of dietary fiber in humans.

The digestion of cellulose, hemicellulose, and lignin has been investigated in humans. Two groups of subjects were studied--healthy subjects with an ileostomy and normal subjects. Both were put on a fixed diet of known cellulose, hemicellulose, and lignin content. From the feces excreted the fiber components were measured by the acid and neutral detergent method. From the small bowel 84.5% of the ingested cellulose was excreted from the ileostomy subjects. From the normal subjects 22.4% of the ingested cellulose was excreted, indicating approximately 80% of the cellulose was digested in the normal subjects. From the water insoluble ingested hemicelluloses 27.5% were excreted from the small bowel, 4.0% from normal subjects. That is approximately 96% digestion of the hemicelluloses in normal subjects. Lignin was found to be undigested in both the small and large bowel. This has important implications in future fiber research.

Cellulose↗
PubMed1975

Purification, properties, and mode of action of hemicellulase I produced by Ceratocystis paradoxa.

A culture isolate (CP2) of the fungal plant pathogen Ceratocystis paradoxa produces at least five extra-cellular hemicellulases when grown on a medium containing a commercial hemicellulose as inducer. One of the five enzymes, hemicellulase I (HC-I), was purified by ammonium sulphate preceipitation, ion-exchange chromatography (DEAE-Sephadex and then Cellex-CM), and iso-electric focusing at pH 3-10 and 8-10. HC-I behaves as a single protein on a electrophoresis at pH 6.0 and 8.4. The enzyme degrades hemicellulose B (an arabino-4-O-methylglucurono-xylan) and arabinoxylanto arabinose, xylose, xylobiose (Xyl2; beta-D-Xylp-(1 leads to 4)-D-Xyl), and a mixture of arabinose-xylose and xylose oligosaccharides (AraXyln and Xyln, where n=3, 4, or 5). The enzyme is deduced to be an endo-enzyme. Xylotetraose (Xyl4) was the lowest homologue of the xylose oligosaccharides attacked, yielding xylobiose and xylotriose (Xyl3) only. A mechanism is postulated for this reaction. AraXyl5 were slowly hydrolysed to arabinose and the respective xylose saccharide (Xyl2-Xyl5), and thence to Xyl2 and Xyl3. Hydrolysis of the arabinofuranosyl linkage probably does not occur at the same active site as for the xylose oligosaccharides. Hemicellulose B fractions from different sources appeared to be degraded by HC-I. The enzyme showed optimum activity at pH 5.5 and 40 degrees, and Km was 4.24 mg of hemicellulose/ml.

Arabinose↗
PubMed1978

Urinary ascorbic acid excretion in the human as affected by dietary fiber and zinc.

The objective of the project was to study the effect of dietary pectin, cellulose, hemicellulose, and zinc on human urinary excretion of ascorbic acid. The project consisted of two 33-day controlled feeding studies involving a total of 19 adult men and women normal health. Within each study all subjects received all experimental treatments. In study A during the four 7-day experimental periods the ground peanut based diets were varied as follows: no supplement, 14.2 g of hemicellulose supplement, 14.2 g of cellulose supplement, or 14.2 g of pectin supplement per subject per day. Mean urinary excretion of ascorbic acid by subjects while receiving these supplements were 26.10, 32.27, 26.27, or 20.60 mg/day, respectively. In study B during the four 7-day randomly arranged experimental periods, the following alterations were made to the basal diet: supplement of 14.2 g of pectin plus 1.3 g of zinc, 14.2 g of pectin plus 9.3 g of zinc, 4.2 g pectin plus 1.3 g of zinc, and 4.2 g of pectin plus 9.3 g of zinc. Mean urinary ascorbic acid excretion of subjects while receiving these diets were as follows: 20.61, 23.18, 28.07, 18.99. Hemicellulose supplement enhanced urinary excretion of ascorbic acid while pectin and zinc resulted in decreased urinary excretion of this vitamin. Increased urinary excretion of ascorbic acid at constant intake levels is thought usually to be indicative of enhanced absorption or of decreased need.

Adult↗
PubMed1992

Cellobiose chemotaxis by the cellulolytic bacterium Cellulomonas gelida.

In the course of a study on the bacterial degradation of plant cell wall polysaccharides, we observed that growing cells of motile cellulolytic bacteria accumulated, without attachment, near cellulose fibers present in the cultures. Because it seemed likely that the accumulation was due to chemotactic behavior, we investigated the chemotactic responses of one of the above-mentioned bacteria (Cellulomonas gelida ATCC 488). We studied primarily the responses toward cellobiose, which is the major product of cellulose hydrolysis by microorganisms, and toward hemicellulose hydrolysis products. We found that cellobiose, cellotriose, D-glucose, xylobiose, and D-xylose, as well as other sugars that are hemicellulose components, served as chemoattractants for C. gelida, as determined by a modification of Adler's capillary assay. Competition and inducibility experiments indicated that C. gelida possesses at least two types of separately regulated cellobiose chemoreceptors (Cb1 and cellobiose, cellotriose, xylobiose, and D-glucose, and it is constitutively synthesized. The presence in C. gelida of a constitutive response toward cellobiose and of at least two distinct cellobiose chemoreceptors has implications for the survival of this cellulolytic bacterium in nature. A possible mechanism for cellobiose-mediated bacterial chemotaxis toward cellulose is proposed. We suggest that, in natural environments, motile cellulolytic bacteria migrate toward plant materials that contain cellulose and hemicellulose by swimming up cellobiose concentration gradients and/or concentration gradients of other sugars (e.g., xylobiose, D-xylose, and D-glucose) formed by enzymatic hydrolysis of plant cell wall polysaccharides.

Actinomycetales↗