Showing papers on "Cellulose published in 1978"

Activated matrix and method of activation

Abstract: Carbonylation of a polysaccharide and the product of that carbonylation. The carbonylated product can be used to prepare an affinity chromatography matrix which is an uncharged species of varying pH's. The carbonylated product is also useful for the preparation of other compounds. Typical polysaccharides are agarose, starch, dextran, cellulose and regenerated cellulose and typical carbonylating agents are N,N'-carbonyl diimidazole; N,N' carbonyl di-1,2,3-benzotriazole; and N,N'-carbonyl di-1,2,4-triazole.

The cellulase of Trichoderma koningii. Purification and properties of some endoglucanase components with special reference to their action on cellulose when acting alone and in synergism with the cellobiohydrolase.

Abstract: 1 Four principal endoglucanase components of Trichoderma koningii cellulase were separated and purified by gel filtration on Sephadex G-75, ion-exchange chromatography on DEAE- and sulphoethyl-Sephadex and isoelectric focusing 2 All four endoglucanases hydrolysed CM-cellulose, H3PO4-swollen cellulose, cellotetraose and cellopentaose, but differed in the rate and mode of attack 3 Attack on cotton fibre by the endoglucanases was minimal, but resulted in changes that were manifested by an increased capacity for the uptake of alkali, and a decrease in tensile strength 4 All four endoglucanases acted synergistically with the exoglucanase [cellobiohydrolase; Wood & McCrae (1972) Biochem J 128, 1183-1192] of T koningii during the early stages of the breakdown of cotton fibre, but only two could produce extensive solubilization of cotton cellulose when acting in admixture with the exoglucanase component 5 The mode of action of the enzymes is discussed in relation to these synergistic effects It is suggested that the results are compatible with the interpretation that the 'crystalline' areas of cotton cellulose are hydrolysed only by those endoglucanases capable of forming of forming an enzyme-enzyme complex with the cellobiohydrolase on the surface of the cellulose chains

Enzyme mechanisms involved in cellulose hydrolysis by the rot fungus Sporotrichum pulverulentum

Abstract: This article presents a review of the enzyme mechanisms involved in degradation of cellulose by the white-rot fungus Sporotrichum poulverulentum. The hydrolytic enzymes involved include: (1) five endo-1,4-β-glucanases; (2) one exo-1,4-β-glucanase, and (3) one or several 1,4-β-glucosidases. A recently discovered oxidative enzyme of importance in in vitro cellulose degradation seems to be a cellobiose oxidase. An oxidoreductase, cellobiose:quinone oxidoreductase, is of importance both in cellulose and in lignin degradation. Regulatory mechanisms of the extracellular enzyme activities, such as monosugar levels causing catabolite repression of the endoglucanases, have also been investigated. The enzymes used by S. pulverulentum in cellulose hydrolysis are compared to those used by Trichoderma viride. Very similar types of enzymes are used in both cases. However, no oxidative enzyme has so far been found to be involved in extracellular cellulose degradation in the case of T. viride. Recommendations for further research are given.

Kinetics of enzymatic hydrolysis of cellulose: Analytical description of a mechanistic model

Abstract: A generalized mechanistic model for the enzymatic hydrolysis of cellulose is developed and expressed mathematically. The model is based on Michaelis–Menten-type kinetics for concurrent random and endwise attack of the substrate involving end-product inhibitions and three types of enzymes: an endo-β;-1,4-glucanase, an exo-β-1,4-glucanase, and β-glucosidase. Basic parameters of the model which can explain synergistic and other effects observed experimentally are quantified and discussed. It is shown that cellulose degradation kinetics are expected to be strongly affected by the ratio of endo- to exocellulases in the reaction mixture as indicated by previous experimental data, and the substrate degree of polymerization, a factor not fully appreciated in previous studies, which appear to be overridingly important in many practical cases.

Enzyme deactivation during cellulose hydrolysis

Abstract: Hydrolysis of cellulose by Trichoderma viride cellulase reached a plateau after some 25 hr. If the initial enzyme-to-substrate ratio was low, resuspension of substrate in fresh enzyme or addition of enzyme resulted in further high rate hydrolysis. This did not occur if the initial ratio was high. Over 75% hydrolysis might be achieved in the former case, while less than 60% in the latter. A model postulating inactivation of adsorbed enzyme–substrate complex which blocked further hydrolysis was proposed, and it was found to fit the data well. The proposed model had five parameters, four of which could be checked by graphical methods, and all of which had physical meanings. The parameters were estimated by a nonlinear least-squares minimization FORTRAN computer program, using numerical integration and optimization of the parameters. The model was used to predict the resuspension data, powdered enzyme addition data, cellobiose addition data, and cellulose addition data; the deviations from the model are discussed. It was found that average values could be used for four out of the five parameters, while the fifth (initial enzyme concentration) did not correlate with independent measurements such as the filter paper activity or protein concentration.

Cellulase and beta-glucosidase production by a basidiomycete species.

Abstract: The optimisation of cellulase and β-glucosidase production by a basidiomycete species was studied and cellulase and cellobiase production by this and Trichoderma viride (and its mutants) in shake flasks were compared. The former produced an active cellulase comparable to that of T. viride when tested on filter paper, carboxymethylcellulose, and cotton; however, it produced 20 to 26 times larger amounts of cellobiase.Both cellulase and β-glucosidase were obtained in good yield only when cellulose was the carbon source. The production of these enzymes was not repressed by readily assimilated carbon sources in the presence of cellulose. Only traces of cellulase and β-glucosidase were formed on glucose, fructose, maltose, and cellobiose although good growth was obtained on these substrates. These enzymes were not induced on sophorose, lactose, mannitol, or glycerol and growth was poor on these substrates. Cellobiose octaacetate was a less effective inducer of cellulase and β-glucosidase than was cellulose.

Effect of sulfur-containing compounds on anaerobic degradation of cellulose to methane by mixed cultures obtained from sewage sludge.

Abstract: Tests were made to determine the effects of inorganic and organic sulfur sources on the degradation of cellulose to methane in a chemically defined medium with sulfur-poor inoculum prepared from sewage sludge. The results show that a sulfur source of about a 0.85 mM concentration is essential for the degradation of cellulose to CH4. However, the production of CH4 from CO2 and H2 provided in the headspace occurred with 0.1 mM sulfate or sulfide. At a 9 mM concentration, all inorganic sulfur compounds other than sulfate inhibited both cellulose degradation and methane formation, and this inhibition increased in the order thiosulfate less than sulfite less than sulfide less than H2S. It appears that the degradation of cellulose to CH4 in a sulfate-free medium by inoculum maintained in a low-sulfur medium is inhibited because of the lack of availability of sulfur for growth of bacteria and synthesis of cell materials and sulfur-containing cofactors involved in cellulose degradation and methanogenesis. The reduction of methanogenesis by higher levels of sulfate probably occurs as a result of stimulation of reactions converting acetate and H2 to end products other than CH4.

Cellulose to sugars: new path gives quantitative yield.

Abstract: Cellulosic residues that had been treated with a small amount of chemical solvent under room conditions were quantitatively saccharified on enzyme hydrolysis. This treatment can be used to obtain simple sugars for the production of alcohol and other chemicals.

Purification and properties of an extracellular β-glucosidase from Lenzites trabea

Abstract: When culturing the cellulolytic-active Basidiomycete and brown-rot fungus Lenzites trabea A-419 in submerged culture with glucose and cellulose as a carbon source, the fungus only excreted β-glucosidase (EC 3.2.1.21) and an endo-1,4-β-glucanase (EC 3.2.1.4). No evidence for C1 activity (EC 3.2.1.91) was found in the culture filtrate or in the ultra concentrate. β-Glucosidase could be separated from endoglucanase by chromatography on Sepharose 6-B. Further fractionation of the β-glucosidase on DEAE-Sephadex A-25 resulted in a 525-fold purification. The molecular weight of the isolated β-glucosidase was determined by co-chromatography on Sephadex G-200 to be 320,000 daltons. The enzyme developed maximum activities at pH 4.5 and 75°C. The enzyme does not act on crystalline cellulose or CMC, but it hydrolyzes cellotriose,-tetraose, and-pentaose to cellobiose and glucose. β-glucosidase activity was strongly inhibited by the reaction product, glucose. A Ki value of 2.7×10−3 (M) for noncompetitive inhibition was found.

Modelling moisture-related mechanical properties of wood Part I: Properties of the wood constituents

Abstract: By starting with simple concepts of the molecular structure and building up through the various levels of organisation in the wood cell wall it is possible to construct a model that simultaneously predicts the variation with moisture content change of both the longitudinal Young's modulus and longitudinal shrinkage of wood. To do this it is first necessary to define the stiffness and swelling characteristics of the lignin, hemicellulose and cellulose constituents of the wood as moisture content changes. It is suggested here that it is the bound fraction of the sorbed water that is responsible for the changes in swelling stress as well as for change in stiffness in the lignin and hemicellulose. The magnitudes of the stiffness of each of the constituents appear to be quite closely circumscribed by experimental values for longitudinal Young's modulus and shrinkage of wood and it is apparent that the stiffness characteristics of the in situ constituents are compatible with available experimental evidence for extracted lignin and hemicellulose and for native cellulose.

Synthesis of Cellulose Precursors

Abstract: Particulate preparations from the Chlorophyta Prototheca zopfii catalyze the incorporation of [14C]glucose from UDP-[14C]glucose into lipids. These lipids have been characterized as lipid-P-glucose, lipid-PP-glucose, and lipid-PP-oligosaccharides. The lipid-linked oligosaccharides were a mixture ranging from a disaccharide to approximately a decasaccharide. Cellulase digestion and periodate oxidation showed that the oligosaccharides seem to be built of β-1,4-linked glucoses. The lipid moiety had the properties of dolichol. The glucolipids described appeared as precursors of a water-soluble polymer. Treatments of this polymer with hydrolytic enzymes and periodate oxidation indicate that it could be a glycoprotein containing β-1,4-linked glucoses. When GDP-glucose was added to the incubation mixture, the 14C-labelled soluble polymer became insoluble in hot alkali. This insoluble polymer had the properties expected for cellulose. A scheme is proposed with the reactions involved in the initiation of cellulose biosynthesis.

Ether-ester derivatives of cellulose and their applications

Abstract: A novel cellulose derivative provided in this invention is a mixed ester of an alkoxy or hydroxyalkoxy substituted cellulose ether, prepared by the esterification reaction of the ether with succinic anhydride and an anhydride of an aliphatic monocarboxylic acid. The cellulose derivatives are advantageous because of their capability of producing enteric coatings having sufficient flexibility without the use of a plasticizer as well as by their chemical and physical stability against moisture, and also by easy purification after completion of the esterification reaction. The coatings produced from the derivatives have a similar chemical and physical stability. The cellulose derivatives are useful for the enteric coating of pharmaceutical dosage forms and also for providing halation-preventing layers on photographic films.

Process for making a shapeable cellulose and shaped cellulose products

Abstract: An improved process is provided for making a precipitated cellulose product wherein cellulose is dissolved in a solvent containing both a tertiary amine N-oxide solvent and water and precipitated therefrom with water or other non-solvent for cellulose. The water content of the solution may be adjusted to any level of up to about 29% by weight with the amount of water decreasing substantially linearly as the cellulose is increased. A solution substantially free from undissolved cellulose and solid tertiary amine N-oxide which is adapted to be spun, extruded or molded at a temperature below the melting point of the tertiary amine N-oxide can be prepared with a solvent which contains water within a specified critical range mixed with the tertiary amine N-oxide. Preferably, N,N,N-triethylamine N-oxide or a tertiary amine N-oxide having a cyclic or pseudo-cyclic molecular structure is mixed with water to form the solvent.

Electron diffraction from the primary wall of cotton fibers

Abstract: Electron diffraction patterns have been obtained from selected areas of disencrusted microfibrils isolated from the primary cell wall of cotton fibers. The resultant fiber diagram has the same meridional repeat distance as a corresponding pattern of secondary wall microfibrils but differs markedly in the equatorial reflections. The primary wall diagram displays only two strong equatorial reflections centered at 0.570 nm and 0.416 nm. The similarity of these spacings with those of cellulose IV suggests that the crystalline structure of the primary wall cellulose is similar to that of cellulose IVI and is best explained in term of native cellulose I crystals having good longitudinal coherence (i.e., coherence along the length of the microfibrils) but with poor lateral organization of the network of inter chain hydrogen bonds. Similar results were also obtained for other primary wall specimens.

Solubility of carbon dioxide in cellulose acetate at elevated pressures

Abstract: The solubility of carbon dioxide in symmetric (dense) cellulose 2.4-acetate has been measured at temperatures from 0 to 70°C and pressures up to 45 atm. The polymer samples were prepared by slowly drying asymmetric reverse osmosis membranes. The solubility isotherms can be described satisfactorily up to 60°C by the “dual-sorption” model for glassy polymers. The model cannot represent the experimental data above 60°C, possibly because of a second-order transition in the polymer between 60 and 70°C. An analysis of the dual-sorption parameters and of the heats of solution and “hole filling” suggests that the polymer samples contained a relatively large volume of microcavities. Gas solution appears to occur predominantly in microcavities, a large fraction of the penetrant moleculers being immobilized or partially immobilized. The solubilities obtained in this work are compared with similar data computed from time-lag measurements of other investigators, and the validity of the dual-sorption model is examined for the present case.

Fermentation Substrates from Cellulosic Materials: Production of Fermentable Sugars from Cellulosic Materials

Abstract: Publisher Summary This chapter discusses the production of fermentable sugars from cellulosic materials. The chapter presents a comparison of the availability and the economy of utilization of cellulosic wastes as an alternative natural resource to those of petroleum crude oil, which is the major raw material source of current chemical industries. The chapter discusses the use of selective solvent extraction to fractionate cellulosic wastes into three individual components: (1) cellulose, (2) hemicellulose, and (3) lignin. Once cellulose is dissolved in a solution, it is neither protected by a crystalline structure nor lignin seal. The composition of cellulosic materials varies widely from plant species to species. It also varies because of different harvesting and storage conditions.

Polysaccharides and glycoproteins in the rice endosperm cell wall.

Abstract: Endosperm cell walls were isolated from rice grains and their chemical composition was analyzed. The cell walls were composed of cellulose microfibrils and matrix phase which consisted of hemicellulose and pectic substances. Hemicellulose mainly comprised arabinoxylan, accompanied by a small amount of glucose-containing polysaccharide. Pectic substances contained polygalacturonides, some of which had side chains containing neutral sugars such as galactose and arabinose. Amino acid analysis of these fractions suggested that hydroxyproline-containing glycoproteins were contained in these cell walls and firmly bound to cellulose microfibrils.

Substrate specificity and mode of action of a cellulase from Aspergillus niger

Abstract: The mode of action and substrate specificity of a cellulase purified from Aspergillus niger were examined. The enzyme showed little capacity to hydrolyse highly ordered cellulose, but readily attacked soluble cellulose derivatives and amorphous alkali-swollen cellulose. Activity towards barley glucan and lichenin was greater than with CM-cellulose. Low activity was detected with CM-pachyman (a substituted beta-1,3-glucose polymer) and xylan. Activity towards yeast glucan, mannan, ethlene glycol chitin, glycol chitosan, laminarin, polygalacturonic acid and pectin could not be demonstrated. Cellobiose and p-nitrophenyl beta-D-glucoside were not hydrolysed, whereas the rate of hydrolysis of the higher members of the reduced cellulodextrins increased with chain length. The central bonds of cellotetraosylsorbitol and cellopentaosylsorbitol were the preferred points of clevage. Kinetic data indicated that the specificity region of the cellulase is five glucose units in length. The evidence indicates that the cellulase is an endoglucanase.

Plastic-wood powder mixture for making insulating material for the electrical industry

Abstract: A method of forming an electrically insulating material having good mechanical properties by mixing a polyvinyl chloride polymer with a natural cellulose material in an amount of from 25 to 30% by weight to form a substantially homogeneous mixture consisting essentially of the polyvinyl chloride and natural cellulose material.

Effect of cooking on vegetable fiber

Abstract: Carrots, cabbage, broccoli and okra, raw, short cooked, and long cooked, were analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, cellulose and hemicellulose by the detergent systems of analysis and crude fiber (CF) by standard methodology. On a dry weight basis, NDF, ADF, CF and cellulose value tended to increase upon cooking. Lignin and hemicellulose value were not affected. Most change was due to cellulose alone. While cooking changes the amount of fiber value present in vegetables studied, the changes may not be of physiological significance considering the small amounts of fiber present in and consumed from these vegetables.

Purification and Partial Characterization of Three Extracellular from Cellulomunas sp.

Abstract: Three extracellular cellulases have been purified from cultures of Cellulomonas. One was found in solution in the cell-free supernatant and two others were found to be bound to the cellulose added as a carbon source. The free enzyme and one of the cellulose-bound enzymes bind to Sephadex. The two cellulose-bound enzymes are glycosylated. The three enzymes behave as endocellulases towards solble carboxymethyl-cellulose and have little activity on cellulose powder.

Single crystals of cellulose II

Abstract: Ribbon-like lamellar single crystals of cellulose II are grown from dilute aqueous solution of cellulose triacetate (number-average degree of polymerization (DP)-15) by deacetylation and consequent precipitation. The best results are obtained with methylamine as the deacetylation reagent at 90°C. Electron diffraction indicates the (110) planes to be the growth face. Twin growth occurs frequently with (110) as the twinning plane.