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Query: KEGG:D03434 (Cellulase)
 512 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cellulase inducer sophorose was rapidly catabolized to CO2 and H2O by Trichoderma: only small amounts were used to induce the synthesis of cellulase. 3H-sophorose uptake began after a lag of 1 h and its half-life in the medium was less than 5 h. Cellulase activity in the medium did not increase till 6 h after the addition of sophorose and reached a half maximum value at 14 h. The presence of free sophorose in the medium was required for continuous cellulase production. Several small sophorose addition induced much more cellulase than an equivalent single dose. These results are attributed to two pathways of sophorose utilization, a catabolic pathway that has a high capacity but low affinity for sophorose and an inductive pathway having a lower capacity but higher affinity for sophorose.
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PMID:Sophorose metabolism and cellulase induction in Trichoderma. 56 Aug 32

Particulate preparations from the Chlorophyta Prototheca zopfi catalyze the incorporation of [14C]glucose from UDP-[14C]glucoe 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 beta-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 that it could be a glycoprotein containing beta-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.
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PMID:Synthesis of cellulose precursors. The involvement of lipid-linked sugars. 63 3

A new compound endowed with agglutinating activity, designated the flour agglutinin, was extracted from wheat flour with water and purified by gel filtration and ion-exchange chromatography. The haptenic inhibitors of the plant agglutinins do not affect flour agglutinin activity which, on the other hand, is inhibited by D- and L-tryptophan. Flour agglutinin has a molecular weight of about 5 - 10(4) as determined by gel filtration. It consists of a neutral heteropolysaccharide constituted of D-xylose and L-arabinose, and is homogeneous as judged by sedimentation analysis. Flour agglutinin activity is destroyed by treatment with Cellulase 2000 and periodate, but is not affected by alpha-amylase and proteolytic enzymes. Compared to germ agglutinin, flour agglutinin exhibits a peculiar range of cell specificity. It agglutinates several normal cell types, but has no effects on some neoplastic cells tested. Tryptic digestion of erythrocytes does not affect their susceptibility to flour agglutinin-induced agglutination.
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PMID:A new agglutinating activity from wheat flour inhibited by tryptophan. 95 30

Various techniques are available for the conversion of lignocellulosics to fuel ethanol. During the last decade processes based on enzymatic hydrolysis of cellulose have been investigated more extensively, showing good yield on both hardwood and softwood. The cellulase production of a filamentous fungi, Trichoderma reesei Rut C 30, was examined on carbon sources obtained after steam pretreatment of spruce. These materials were washed fibrous steam-pretreated spruce (SPS), and hemicellulose hydrolysate. The hemicellulose hydrolysate contained, besides water-soluble carbohydrates, lignin and sugar degradation products, which were formed during the pretreatment and proved to be inhibitory to microorganisms. Experiments were performed in a 4-L laboratory fermentor. The hydrolytic capacity of the produced enzyme solutions was compared with two commercially available enzyme preparations, Celluclast and Iogen Cellulase, on SPS, washed SPS, and Solka Floc cellulose powder. There was no significant difference among the different enzymes produced by T. reesei Rut C 30. However, the conversion of cellulose using these enzymes was higher than that obtained with Iogen or Celluclast cellulases using steam-pretreated spruce as substrate.
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PMID:Cellulase production of Trichoderma reesei Rut C 30 using steam-pretreated spruce. Hydrolytic potential of cellulases on different substrates. 1084 27

The changes in cellular wall hydrolases, cellular wall components and cellular wall ultrastructure of postharvest persimmon (Diospyros kaki L. cv. Bianhua) fruit during softening were studied. Pectinesterase activity increased sharply at first and reached a peak (Fig.3A). Significant correlation was observed between the pectinesterase activity and the loss of flesh firmness (r= -0.74). Polygalacturonase activity increased slowly (Fig.3B), but there was no significant correlation between the polygalacturonase activity and the loss of flesh firmness. Beta-galactosidase activity increased sharply (Fig.3C), with a negative correlation between the b-galactosidase activity and the loss of flesh fruit firmness (r= -0.77). Cellulase activity increased markedly during ripening (Fig.3D). Significant correlation was observed between cellulase activity and the loss of flesh firmness (r= -0.90). Consistent with the increases in activity of cell wall hydrolases of cell wall constituents, fruit softening was accompanied by a progressive increase in WSP (water soluble pectin) content and a progressive decrease in protopectin and cellulose content (Fig.4). The cell wall structure was integrated when persimmon was harvested (Fig.5A). After 3 d of ripening, the middle lamella became liquefied (Fig.5B), or even the primary cell wall was dissolved in some regions (Fig.5C).
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PMID:[Changes in cell wall component metabolism and ultrastructure of postharvest persimmon fruit during softening]. 1636 94

Tifton 85 bermudagrass, developed at the ARS-USDA in Tifton, GA, is grown on over ten million acres in the USA for hay and forage. Of the bermudagrass cultivars, Tifton 85 exhibits improved digestibility because the ratio of ether- to ester-linked phenolic acids has been lowered using traditional plant breeding techniques. A previously developed pressurized batch hot water (PBHW) method was used to treat Tifton 85 bermudagrass for enzymatic hydrolysis. Native grass (untreated) and PBHW-pretreated material were compared as substrates for fungal cultivation to produce enzymes. Cellulase activity, measured via the filter paper assay, was higher for fungi cultivated on PBHW-pretreated grass, whereas the other nine enzyme assays produced higher activities for the untreated grass. Ferulic acid and vanillin levels increased significantly for the enzyme preparations produced using PBHW-pretreated grass and the release of these phenolic compounds may have contributed to the observed reduction in enzyme activities. Culture supernatant from Tifton 85 bermudagrass-grown fungi were combined with two commercial enzyme preparations and the enzyme activity profiles are reported. The amount of reducing sugar liberated by the enzyme mixture from Hypocrea jecorina (after 192 h incubation with untreated bermudagrass) individually or in combination with feruloyl esterase was 72.1 and 84.8%, respectively, of the commercial cellulase preparation analyzed under the same conditions.
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PMID:Evaluation of a Hypocrea jecorina enzyme preparation for hydrolysis of Tifton 85 bermudagrass. 1842 90

Treatment of wheat straw with 1N trifluoroacetic acid (TFA) for 7 h at reflux temperature yielded 23% xylose based upon initial straw weight. This corresponds to about an 80% xylose yield based on the xylan content of the hemicellulose. The cellulose component of wheat straw was largely unaffected, as evidenced by low glucose yields. Decomposition of xylose by prolonged refluxing (23 h) was minimal in 1N TFA compared to 1N HCl. Treatment of wheat straw with refluxing 1N TFA converts about 10% of the lignin initially present in straw into water-soluble lignin fragments. Fermentation of the xylose-rich wheat straw hydrolyzate to ethanol with Pachysolen tannophilus was comparable to the fermentation of reagent grade xylose, indicating that furfural and toxic lignin by-products were not produced by 1N TFA in sufficient amounts to impair cell growth and ethanol production. Cellulase treatment of the wheat straw residue after TFA hydrolysis resulted in a 70-75% conversion of the cellulose into glucose.
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PMID:Hydrolysis of wheat straw hemicellulose with trifluoroacetic acid. Fermentation of xylose with Pachysolen tannophilus. 1855 35

Cellulase (Cellulosin AC-8) was immobilized on poly-L-glutamic acid. This immobilized cellulase (IC) is water soluble in the neutral and alkaline solutions, where IC has the activity, while IC can be made insoluble by lowering the pH so that it can be recovered from the reaction mixture with its activity. The optimum pH and temperature were determined to be 5.5 and 55 degrees C, respectively. The stability of IC against change in the pH and temperature was improved by the immobilization. Solvolysis of 3N-NaOH-treated cellulose, with IC under the optimum conditions found here, led to the production of low-molecular-weight compounds.
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PMID:Cellulase immobilized on poly-L-glutamic acid. 1857 70

The cellulose dissolution solvent used in Lyocell process for cellulose fiber preparation, N-methylmorpholine-N-oxide (NMMO) monohydrate, was demonstrated to be an effective agent for sugarcane bagasse pretreatment. Bagasse of 20wt% was readily dissolved in NMMO monohydrate at 130 degrees C within 1h. After dissolution, bagasse could be regenerated by rapid precipitation with water as a porous and amorphous mixture of its original components. The regenerated bagasse exhibited a significant enhancement on enzymatic hydrolysis kinetic. Not only the reducing sugars releasing rate but also hydrolysis yield was enhanced at least twofold as compared with that of untreated bagasse. The cellulose fraction of regenerated bagasse was nearly hydrolyzed to glucose after 72h hydrolysis with Cellulase AP3. The recycled NMMO demonstrated the same performance as the fresh one on bagasse pretreatment for hydrolysis enhancement. The regenerated bagasse was directly used in simultaneous saccharification and fermentation (SSF) for ethanol production by Zymomonas mobilis. No negative effect on ethanol fermentation was observed and ethanol yield approximately 0.15 g ethanol/g baggasse was achieved.
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PMID:Enhanced enzymatic hydrolysis of sugarcane bagasse by N-methylmorpholine-N-oxide pretreatment. 1871 63

Biomass feedstock having less competition with food crops are desirable for bio-ethanol production and such resources may not be localized geographically. A distributed production strategy is therefore more suitable for feedstock like water hyacinth with a decentralized availability. In this study, we have demonstrated the suitability of this feedstock for production of fermentable sugars using cellulases produced on site. Testing of acid and alkali pretreatment methods indicated that alkali pretreatment was more efficient in making the sample susceptible to enzyme hydrolysis. Cellulase and beta-glucosidase loading and the effect of surfactants were studied and optimized to improve saccharification. Redesigning of enzyme blends resulted in an improvement of saccharification from 57% to 71%. A crude trial on fermentation of the enzymatic hydrolysate using the common baker's yeast Saccharomyces cerevisiae yielded an ethanol concentration of 4.4 g/L.
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PMID:Bio-ethanol from water hyacinth biomass: an evaluation of enzymatic saccharification strategy. 1979 35


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