The Cellulase System of <i>Trichoderma</i>

Gritzali, Mikelina; Brown, Ross

doi:10.1021/ba-1979-0181.ch012

Cited by 162 publications

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“…Cellobiohydrolase I(D), cellobiohydrolase I1 and endoglucanase were reported to comprise about 60%, 25% and 15% (w/w), respectively, of total protein secreted by T. reesei [2].…”

Section: Discussionmentioning

confidence: 99%

“…When grown on cellulose or induced by sophorose (2-0-p-~-glucopyranosyl-a-D-glucopyranose) T. reesei QM9414 elaborates the full complement of cellulolytic enzymes into the extracellular medium [2, 31. The cellulase system comprises 1,4-P-~-glucan 4-glucanohydrolases, 1,4-b-~-glucan cellobiohydrolases and b-glucosidases, which together act sequentially and cooperatively to convert native, crystalline cellulose to oligosaccharides and glucose [2]. Endoglucanases randomly attack internal glycosidic bonds of cellulose chains, thereby producing polymer chain ends and soluble oligosaccharides.…”

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confidence: 99%

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Purification and characterization of a β‐glucosidase from Trichoderma reesei

Chirico

Brown

1987

European Journal of Biochemistry

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A $-glucosidase has been purified from culture filtrates of the fungus Trichoderma reesei QM9414 grown on microcrystalline cellulose. The P-glucosidase was purified using two successive DEAE-Sephadex anion-exchange chromatography steps, followed by SP-Sephadex cation-exchange chromatography and concanavalin-A -agarose chromatography. Evidence for homogeneity is provided by polyacrylamide disc gel electrophoretic patterns, which show a single protein band.Sedimentation equilibrium analysis yielded a molecular mass of 74.6 f 2.4 kDa. Sodium dodecyl sulfate/ polyacrylamide gel electrophoresis yielded a single protein band with a molecular mass of 81.6 kDa. Thus, the enzyme appears to be a single, monomeric polypeptide. The P-glucosidase is isoelectric at pH 8.5. The enzyme is rich in basic amino acids and contains few half-cystine and methionine residues. The purified P-glucosidase contains less than 1 YO by weight of neutral carbohydrate.The P-glucosidase catalyzes the hydrolysis of cellobiose, p-nitrophenyl 8-D-glucopyranoside and 4-methylumbelliferyl P-D-glucopyranoside; the values of V / K , for each substrate were determined to be 2.3 x lo4, 6.9 x lo5 and 2.9 x 106 M-' s-' respectively. The enzyme is optimally active from pH 4.5 to 5.0 and is labile at higher hydrogen ion concentrations. The P-glucosidase has an unusually high affinity for D-glucose (Ki = 700 pM).Comparison of inhibition constants for cello-oligosaccharides suggests that the substrate-binding region of the P-glucosidase comprises multiple subsites.One of the best sources of cellulolytic enzymes is the fungus Trichoderma reesei, which possesses the complete array of enzymes required for conversion of cellulose to glucose El]. When grown on cellulose or induced by sophorose (2-0-p-~-glucopyranosyl-a-D-glucopyranose) T. reesei QM9414 elaborates the full complement of cellulolytic enzymes into the extracellular medium [2, 31. The cellulase system comprises 1,4-P-~-glucan 4-glucanohydrolases, 1,4-b-~-glucan cellobiohydrolases and b-glucosidases, which together act sequentially and cooperatively to convert native, crystalline cellulose to oligosaccharides and glucose [2]. Endoglucanases randomly attack internal glycosidic bonds of cellulose chains, thereby producing polymer chain ends and soluble oligosaccharides. Cellobiohydrolases cleave cellobiosyl residues from the ends of cellulose chains. P-Glucosidases catalyze the hydrolysis of cellobiose, which is inhibitory to the depolymerizing enzymes, and oligosaccharides to glucose.

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“…Cellobiohydrolase I(D), cellobiohydrolase I1 and endoglucanase were reported to comprise about 60%, 25% and 15% (w/w), respectively, of total protein secreted by T. reesei [2].…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Purification and characterization of a β‐glucosidase from Trichoderma reesei

Chirico

Brown

1987

European Journal of Biochemistry

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“…CBH activity is rate-limiting for cellulose hydrolysis [50] and CBHs make up the majority of protein mass in commercial cellulase mixtures [13]. Further, we would expect the same to be true for sugar cane bagasse pretreated using the alkaline, green solvent, and physical processes described herein.…”

Section: Discussionmentioning

confidence: 69%

“…A minimum of four cellulases is required for complete cellulose saccharification, and each is derived from a different functional class: (i) an endo-1,4-β-D-glucanase (endoglucanase) that hydrolyses cellulose regions with low crystallinity (called amorphous regions), creating free chain ends; (ii) two exo-1,4-β-D-glucanases (cellobiohydrolases (CBHs)), that cleave cellobiose units from either the reducing or non-reducing free chain ends; and (iii) a β-glucosidase (βG) that hydrolyses cellobiose to glucose [12]. CBHs catalyse the majority of bond cleavages during cellulose hydrolysis and are usually the major component of fungus-derived commercial cellulase mixtures [13] or artificial enzyme mixtures for cellulose hydrolysis [14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

The combination of plant-expressed cellobiohydrolase and low dosages of cellulases for the hydrolysis of sugar cane bagasse

Harrison

Zhang

Shand

et al. 2014

Biotechnol Biofuels

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Background: The expression of biomass-degrading enzymes (such as cellobiohydrolases) in transgenic plants has the potential to reduce the costs of biomass saccharification by providing a source of enzymes to supplement commercial cellulase mixtures. Cellobiohydrolases are the main enzymes in commercial cellulase mixtures. In the present study, a cellobiohydrolase was expressed in transgenic corn stover leaf and assessed as an additive for two commercial cellulase mixtures for the saccharification of pretreated sugar cane bagasse obtained by different processes. Results: Recombinant cellobiohydrolase in the senescent leaves of transgenic corn was extracted using a simple buffer with no concentration step. The extract significantly enhanced the performance of Celluclast 1.5 L (a commercial cellulase mixture) by up to fourfold on sugar cane bagasse pretreated at the pilot scale using a dilute sulfuric acid steam explosion process compared to the commercial cellulase mixture on its own. Also, the extracts were able to enhance the performance of Cellic CTec2 (a commercial cellulase mixture) up to fourfold on a range of residues from sugar cane bagasse pretreated at the laboratory (using acidified ethylene carbonate/ethylene glycol, 1-butyl-3-methylimidazolium chloride, and ball-milling) and pilot (dilute sodium hydroxide and glycerol/hydrochloric acid steam explosion) scales. We have demonstrated using tap water as a solvent (under conditions that mimic an industrial process) extraction of about 90% recombinant cellobiohydrolase from senescent, transgenic corn stover leaf that had minimal tissue disruption.

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“…Some of these enzymes have been purified to homogeneity (e.g., two exocellobiohydrolases, endocellulases and a P-glucosidase) [ 1,2].…”

Section: Introductionmentioning

confidence: 99%

The use of 4‐methylumbelliferyl and other chromophoric glycosides in the study of cellulolytic enzymes

1982

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HPLC‐analysis of the reaction products of a series of 4‐methylumbelliferyl glycosides from cello‐oligosaccharides, used as substrates of a cellobiohydrolase from Trichoderma reesei, proves the lack of specificity for terminal cellobiosyl groups. Also, different reaction patterns are observed for this CBHI and for an endocellulase, when acting on these same substrates. 4‐Methylumbelliferyl β‐D‐lactoside is an unexpected substrate for CBHI, yielding only lactose and phenol as reaction products. The binding characteristics of p‐nitrobenzyl 1‐thio‐β‐D‐lactoside for this enzyme are determined by a dia‐filtration technique, yielding 1 binding site and an association constant of 4.0 × 104 M−1.

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The Cellulase System of Trichoderma

Cited by 162 publications

References 0 publications

Purification and characterization of a β‐glucosidase from Trichoderma reesei

Purification and characterization of a β‐glucosidase from Trichoderma reesei

The combination of plant-expressed cellobiohydrolase and low dosages of cellulases for the hydrolysis of sugar cane bagasse

The use of 4‐methylumbelliferyl and other chromophoric glycosides in the study of cellulolytic enzymes

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