Non-cellulosic Glucans Research Articles

Steam explosion of Brewer's spent grain improves enzymatic digestibility of carbohydrates and affects solubility and stability of proteins.

Steam explosion was studied as a means to improve the enzymatic digestibility of carbohydrates in Brewer's spent grain, a protein and lipid-rich lignocellulosic by-product of the brewing industry. Having temperature, treatment time and the presence of acid catalyst as variables, a treatment at 200°C for 10min without an acid catalyst was found to be the most efficient, dissolving12.1% of the dry matter. Mainly oligomeric non-cellulosic glucan and arabinoxylan were dissolved, and the remaining insoluble carbohydrates could be efficiently hydrolysed by an enzyme cocktail (75% hydrolysis yield). The process also caused partial protein degradation and dissolved over a third of the total nitrogen. Meanwhile, the insoluble protein appeared to become more strongly associated with acid-insoluble lignin. Compositional changes observed in the proteins and carbohydrates were supported by the results of epifluorescence microscopy. The process yielded three chemically different fractions which could serve as biorefinery products or intermediates.

Non-cellulosic glucans as novel initiators for human keratinocyte differentiation: a new approach for wound healing

The epidermis is a layered tissue consisting particularly of keratinocytes and undergoes continuous regeneration. During a stringently regulated process of terminal differentiation, which is a crucial step during wound healing, keratinocytes move upward to the stratum corneum and undergo complex morphological and biochemical alterations.

Validation of PyMBMS as a High-throughput Screen for Lignin Abundance in Lignocellulosic Biomass of Grasses

Pyrolysis molecular-beam mass spectrometry (PyMBMS) was tested as a high-throughput method for relative abundances of guaiacyl and syringyl lignin in lignocellulosic cell-wall materials from stems of a population of maize intermated B73 × Mo17 (IBM) recombinant inbred lines. Variations of up to twofold across the population in phenylpropanoid abundance were observed. Several histochemical and quantitative biochemical assays were used to validate the mass spectrometric data for lignin, hydroxycinnamic acids, crystalline cellulose, non-cellulosic glucans, and xylans. We demonstrate PyMBMS to be a valid high-throughput screen suitable for analysis of lignin abundance in large populations of bioenergy grasses. Pentose from xylans and hexose from cellulosic and non-cellulosic glucans also varied substantially across the population, but abundances of diagnostic fragments for these monosaccharides were not well correlated with the abundance of cell-wall polysaccharides.

Non-cellulosic glucans as inductors for differentiation of human keratinocytes

The epidermis is a dynamic renewing structure, principally formed by highly specialized keratinocytes. During a carefully choreographed program of differentiation keratinocytes undergo complex morphological and biochemical changes.

Enzymatic saccharification of duckweed (Lemna minor) biomass without thermophysical pretreatment

Duckweed is a rapidly replicating aquatic plant that has the potential to decontaminate effluent streams from food processing and also has a low-lignin content. Hence it could provide a more suitable source of cellulose for conversion to biofuels.This paper reports that duckweed biomass has the potential to be enzymatically saccharified to produce glucose and other cell-wall-derived sugars which might be converted to ethanol by fermentation or exploited as industrial platform chemicals. The enzymatic digestibility has been studied on alcohol-extracted, water-insoluble preparations of duckweed cell walls. Within these, glucose accounts for w = 25.4% (dry wt), which has arisen from cellulose and non-cellulosic glucans including starch. Several commercial cell-wall degrading enzymes and cocktails have been evaluated. Saccharification can be achieved within about 8 h using commercial cellulase at 4.35 FPU g−1 substrate in conjunction with added beta-glucosidase at 100 U g−1 substrate. The potential for exploiting duckweed is discussed.

Characterization of non-cellulosic glucans in Eucalyptus globulus Labill. wood and kraft pulp

Abstract The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90–120°C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120°C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and amylopectin (80%), although a small proportion of β-(1→3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of α-glucan is precipitated onto the fiber surface and contributes to the pulp yield.

Changes in the Cell Wall of Olive Fruit during Processing

Olive fruits were sampled at various stages during their progress through the «California Black Ripe» process. Analysis of cell walls prepared from these fruits indicated that processing was accompanied by general solubilization ofpolysaccharides and that pectins and a noncellulosic glucan component were most clearly affected. Soluble polysaccharides accumulated in processing liquids. Analysis of these and of polysaccharides extracted from cell walls suggests that the polymer most extensively solubilized and eluted during processing is a relatively unbranched pectin

Pythium aphanidermatum: culture, cell-wall composition, and isolation and structure of antitumour storage and solubilised cell-wall (1 → 3),(1 → 6)-β- d-glucans

Under optimal conditions for the culture of the fungus Phytium aphanidermatum, no polysaccharides were excreted into the medium. The mycelium contained up to 38% of a slightly branched, storage (1 → 3),(1 → 6)-β- d-glucan with a MW of 20 000. The cell=wall polysaccharides of the mycelium comprised 18% of cellulose and 82% of (1 → 3),(1 → 6)-β- d-glucans. Of the non-cellulosic glucans, ∼ 33% could be solubilised by extraction with water at 121°, and they had a MW of 10 000, were highly branched, and contained 6% (of (1 → 6) linkages. Treatment of the cell wall with 0.1 M trifluoroacetic acid released ∼ 50% of the non-cellulosic glucans. The acid-soluble cell-wall (1 → 3),-(1 → 6)-β- d-glucans of lower MW (6000) were still highly branched and contained 14% of (1 → 6) and 8% of (1 → 4) linkages. The storage glucan and the hot-water-soluble cell-wall glucan exhibited strong activity against the Sarcoma 180 in CD-1 mice, whereas the acid-soluble cell-wall glucans were inactive. The hot-water-soluble cell-wall was also active against the DBA/2-MC.SC-1 fibrosarcoma in DBA/2 mice.

Influence of growth conditions on the composition of cell wall polysaccharides from cultured tobacco cells

The sugar composition of cell wall polysaccharides of two tobacco varieties obtained from mesophyll, regenerating protoplasts and cells grown under various conditions were compared. Regenerating protoplasts developed an unusual cell wall with a low cellulose and a high non-cellulosic glucan content. In the presence of different phytohormones compact and friable calli were obtained with cell walls containing low and high arabinose/xylose ratios. The cell walls of compact calli were comparable to those of genuine mesophyll cells. The sugar constituents of cell walls obtained from cells grown in liquid media were different from those of solid calli. The cell wall composition of suspension cultured cells was hardly affected by various combinations of phytohormones, but was altered by high osmolarity of the medium.

Composition of cell walls from cotyledons of Pisum sativum, Vicia faba and Glycine max

Cell walls from cotyledons of smooth field pea, broad bean and soya bean contain ca 55% pectic polysaccharides associated with 9% cellulose. Arabinose is the major pectic sugar of pea and broad bean walls whereas soya bean pectic polymers are constituted of galactose and arabinose in the ratio (2:1). Galacturonic acid represents ca 20% of the walls. In addition, pea and broad bean cell walls contain, respectively, 12% and 6% of non-starchy and non-cellulosic glucans bearing 4,6-linked and 3-linked glycosyl units. EDTA-soluble acidic pectic substances are distinct rhamnogalacturonans bearing decreasing proportions of interrupting rhamnose from highly interrupted moieties to nearly homogenous homogalacturonans. Pea and broad bean rhamnogalacturonans are associated with arabinose-containing polymers of average DP ca 30–35 whereas soya bean ones have side chains of arabinose and galactose of DP ca 40.

Glucan synthesis by intact cotton fibres fed with different precursors at the stages of primary and secondary wall formation

Seed clusters of individual locules from fruit capsules of Gossypium arboreum L. with adhering intact fibres were fed with radioactive uridinediphosphoglucose (UDPG), guanosinediphosphoglucose (GDPG), glucose and sucrose. The incorporation into high molecular weight glucans of the fibres was studied. For primary wall fibres, UDPG at 1 mM was by far the best precursor, whereas sucrose was the best precursor for secondary wall fibres. No competition was observed between the incorporation of glucose from UDPG and from sucrose when the two were fed simultaneously to secondary wall fibres, indicating that their metabolic pathways are well separated when they are fed from the apoplast. Inhibitors of respiratory ATP-formation strongly inhibited incorporation of sucrose but not that of UDPG. Sucrose incorporation was studied at five different stages of development of the cotton fibres. At the stage of most intense secondary wall formation the incorporation rate was about 300 times that during primary wall formation (24 days post anthesis (DPA)). Incorporation from 1 mM UDPG or GDPG by secondary wall fibres (35 DPA) was less than twice that of primary wall fibres (22 DPA), indicating that the two sugar nucleotides are not readily used as precursors for secondary wall cellulose when they are fed to the exterior of intact cells. The high molecular weight non-cellulosic glucans formed from UDPG and sucrose at 5 and 1,000 μM were solubilized in strongly alkaline solutions or dimethyl-sulfoxide (DMSO) and were partially characterized by degradation with an exo-β-1,3-glucanase. After feeding for one hour, at most 1/3 of the radioactivity in high molecular weight material was found in cellulose and at least 2/3 in β-1,3-glucan. The proportions varied little for fibres in the age range of 30 to 48 DPA when sucrose was the precursor although the total incorporation varied by a factor of about four. The fact that at all stages of secondary wall formation β-1,3-glucan is synthesized at a very high rate, but that the total amount in the cell wall does not exceed 2% in the later stages of wall formation, can be interpreted in terms of a high turnover of this polysaccharide if it is assumed that wound effects are negligible in the system under study.

β-1,3-Glucans in the cell walls of cotton fibres ( Gossypium arboreum L.)

Extracts of cell walls from growing cotton fibres contain appreciable amounts of non-cellulosic glucans. Hydrolysis of these glucans by different types of glucanases and analysis of the degradation products as well as periodate oxidation and methylation studies, showed that they are essentially composed of β-1,3-linked glucose residues.

Composition of the cell wall formed by protoplasts isolated from cell suspension cultures of Vinca rosea

The biochemistry of cell-wall regeneration in protoplasts obtained from Vinca rosea L. (Catharanthus roseus (L.) G. Don) cells grown in suspension culture by isolating the regenerated wall and the extracellular polysaccharides of protoplasts cultured for various periods, and investigating their composition. Gas-liquid chromatography and tracer studies with D-[U-(14)C]glucose showed that the sugar composition of the extracellular polysaccharides was similar to that of the original cell culture, consisting mainly of polyuronide and 3,6-linked arabinogalactan. the regenerated cell wall was composed of non-cellulosic glucans having 1,3- and 1,4-linkages, while its content in pectic and hemicellulosic components was very low.

Structure of hemicellulosic polysaccharides of Avena sativa coleoptile cell walls

The glycosidic linkage compositions of intact and, in some cases, enzyme-degraded polysaccharides extracted from the cell walls of oat coleoptiles and subsequently purified have been examined. A major component is shown to be a glucuronoarabinoxylan similar in structure to those described for a variety of other monocots. The noncellulosic glucan component is a β-linked polymer containing both 1,4- and 1,3-linked glucosyl residues in a ratio of 2 to 1. Analysis of the oligosaccharide produced by ‘lichenase’ digestion of this β-glucan suggests that the the 1,3- and 1,4-glucosyl linkages repeat in regular fashion. A small amount of xyloglucan polysaccharides like those described for cell walls of dicots was also detected.

Pollen tube growth in the stigma of Oenothera organensis following compatible and incompatible intraspecific pollinations

The growth of the pollen tube wall of Oenothera organensis results from the insertion of bodies, composed principally of fibrils, synthesized in cytoplasm. This material for the early growth of the tube wall is derived from double membraned inclusions, present in the pollen on release from the anther. The wall of the later tube is derived from the products of dictyosome vesicles, believed to be non-cellulosic glucans. Some of these vesicles, which are formed in very large numbers on germination of the pollen grain, form an association with banked complexes of mitochondria, and it is proposed that this association indicates that phosphorylation of glucan precursors occurs within the vesicles, rather than in the dictyosome. The mechanism of tube wall growth following incompatible cross-pollinations is identical with that following compatible crosses. The early incompatible tube, however, contains far lower levels of free carbohydrates. Among these carbohydrates must be the precursors required for glucan synthesis, for the tube wall is laid down only thinly at this stage. Once the incompatible tube has passed through the outer layer of the stigmatic cells and their secretion, growth similar to that of a compatible tube starts. Subsequent growth of the tube appears to depend upon the amount of reserve material that passes through the region of low carbohydrate content. While the early interactions between the pollen and stigma are far from understood, it is clear that the self-incompatibility system acts principally during growth of the tube in the viscous fluid coating the outer stigmatic cells.

?-Glucanases and non-cellulosic glucans in the developing oat plant

The changes in the levels of various β-glucan hydrolase activities in the second internode of the stem of the developing oat plant have been examined. Concurrent changes in the non-cellulosic β-glucans contained in the corresponding total hemicelluloses were also studied. Possible relationships between the observed changes and the growth and development of the plant tissue are discussed.

Isolation and characterization of secretory vesicles in germinated pollen of Lilium longiflorum

ABSTRACT Secretory vesicles containing polysaccharide were isolated from germinated pollen of Lilium longiflorum and characterized by biochemical and ultrastructural investigation. Pollen tubes exhibit a secretory pathway in which the vesicles concentrated in the tube apex are produced by the Golgi apparatus and contributed to the cell wall at the apex upon fusion of the vesicle membrane with the plasma membrane. Secretory vesicles were isolated by a method involving the size discrimination of cytoplasmic components using Millipore filters. Cells were disrupted under conditions which minimized membrane vesiculation. Identification was made by electron-microscopic comparison of the periodic acid-silver hexamine (PASH) reactivities of in situ and isolated secretory vesicles. The secretory vesicles contained polysaccharides which were high in galacturonic acid and similar in sugar composition to those of the hot-water-soluble fraction of pollen tube cell wall. A hot-water-insoluble, non-cellulosic glucan was the major component of the cell wall. Less than 7 % of the wall was cellulosic. Chitin was absent. Similarities in the ultrastructure and PASH staining of apical secretory vesicles and an amorphous component of the cell wall support a precursor-product relationship between these 2 cell components. Ultrastructural investigations revealed complexes of the endoplasmic reticulum (ER) associated with electron-translucent regions of cytoplasm, suggesting a possible function of the ER in cell wall formation. Additionally, patterns of PASH staining show that changes in polysaccharides occur in secretory vesicles after vesicles have been formed by dictyosomes. Therefore, secretory vesicles may have a role in polysaccharide synthesis as well as in membrane and product transport.

Total hemicelluloses from oat plants at different stages of growth

Total hemicelluloses have been isolated from the leaves and stems of field-grown oat plants and from the leaves, roots and coleoptiles of plants grown in the laboratory. In any one part of the plant, with increasing maturity there is an increase in the percentage of xylose and a decrease in the percentage of glucose residues. These changes and accompanying changes in the percentages of galactose and arabinose residues are considered in terms of three pure hemicelluloses known to be present—an arabinoxylan, an acidic galactoarabinoxylan and a non-cellulosic glucan. Pure galactoarabinoxylans were isolated from the leaves of field-grown oat plants at different stages of growth. The results indicate that it is inappropriate to study the effect of growth on hemicellulosic composition solely by considering pure hemicelluloses.

Peroxyacetyl nitrate-induced inhibition of cell wall metabolism.

Levels of PAN which inhibit oat coleoptile section growth reversibly, severely inhibit metabolism of cellulose and of cell wall noncellulosic polysaccharides. An enzyme in the coleoptile cell walls which hydrolyzes some of the noncellulosic glucan was partially inactivated by direct PAN treatment of homogenized cell wall. Treatment of intact cells by PAN also resulted in a partially inactivated enzyme. Coleoptile phos-phoglucomutase was partially inactivated by treatment with PAN both in vitro and in vivo. After treatment of intact cells with PAN, phosphoglucomutase associated with subcellular particles was more severely inactivated than was soluble enzyme. Uridine diphosphate glucose pyrophosphorylase from coleoptiles was inactivated by PAN in vitro but not in vivo. A particulate cellulose synthetase from coleoptiles was inactivated by PAN both in vitro and in vivo. Since cell wall biosynthesis and or degradation are needed for expansion it is concluded that PAN inhibition of these enzymes may account fo...

Studies on Cellulose Synthesis by a Cell-free Oat Coleoptile Enzyme System: Inactivation by Airborne Oxidants

Particulate cell wall polysaccharide synthetase from oat coleoptiles could use either guanosine diphosphate glucose or uridine diphosphate glucose; the latter was a much more effective glucose donor. The neutral polymer derived from uridine diphosphate glucose utilization yielded, after cellulase digestion, mostly cellobiose and to a lesser extent a substance tentatively identified as a mixed-linkage beta1,4 = beta1,3-trisaccharide; only cellobiose was found after guanosine diphosphate glucose utilization. The uridine diphosphate glucose utilizing system was inactivated by peroxyacetyl nitrate treatment of intact tissue and to a lesser extent by ozone treatment suggesting that this system is a possible site of interference with cellulose and non-cellulosic glucan biosynthesis in vivo. Direct treatment of the enzyme in vitro by peroxyacetyl nitrate, iodoacetamide or p-chloromercuribenzoate also inactivated the enzyme, indicating that the mechanism of inactivation possibly involves reaction with sulfhydryl groups.