Subsite structure of the β-glucosidase from Aspergillus niger, evaluated by steady-state kinetics with cello-oligosaccharides as substrates

Yazaki, Terutaka; Ohnishi, Masatake; Rokushika, Souji; Okada, Gentaro

doi:10.1016/s0008-6215(96)00287-x

Cited by 26 publications

(7 citation statements)

References 32 publications

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“…Further it was employed in the determination of binding affinities for various exo‐glycosidases: α‐glucosidase [49], β‐glucosidases [50,51] and glucoamylases [47,52]. The results obtained for α‐glucosidase [49] as well as for β‐glucosidases from Aspergillus niger [50] and Candida wickerhamii [51] demonstrated that for these enzymes the active center affinity for substrates decreases as the DP of the substrate increases: consequently, A −1 to A 3 have positive values. A β‐glucosidase from germinated barley has been reported to have negative affinity at site +2 and positive at the rest [53].…”

Section: Resultsmentioning

confidence: 99%

Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride

Kulminskaya

Thomsen

Shabalin

et al. 2001

European Journal of Biochemistry

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An exo-1,3-b-glucanase has been isolated from cultural filtrate of Trichoderma viride AZ36. The N-terminal sequence of the purified enzyme (m ¼ 61^1 kDa) showed no significant homology to other known glucanases. The 1,3-b-glucanase displayed high activity against laminarins, curdlan, and 1,3-b-oligoglucosides, but acted slowly on 1,3-1,4-b-oligoglucosides. No significant activity was detected against high molecular mass 1,3-1,4-bglucans. The enzyme carried out hydrolysis with inversion of the anomeric configuration. Whereas only glucose was released from the nonreducing terminus during hydrolysis of 1,3-b-oligoglucosides, transient accumulation of gentiobiose was observed during hydrolysis of laminarins. The gentiobiose was subsequently degraded to glucose. The Michaelis constants K m and V max have been determined for the hydrolysis of 1,3-b-oligoglucosides with degrees of polymerization ranging from 2 to 6. Based on these data, binding affinities for subsites were calculated. Substrate binding site contained at least five binding sites for sugar residues.Keywords: exo-1; 3-b-glucanase; Trichoderma viride; anomerity of hydrolysis. [6,7], and marine organisms [8,9]. It has been suggested that plant 1,3-b-glucanases may protect the germinating grain against pathogen attack [10]. Microbial 1,3-b-glucanases play an essential role in development and differentiation of saprophyte and mycoparasite cultures [11 -13] while 1,3-b-glucanases from the filamentous fungi Coprinas seem to be involved in the process of stipe elongation [14]. In Saccharomyces cerevisiae the production of exo-1,3-b-glucanases is growth-associated and cellcycle regulated, suggesting that their activities are required at specific stages during morphogenesis [15,16]. Most organisms synthesize multiple 1,3-b-glucanases rather than a single enzyme [17] and complete degradation of 1,3-bglucans by fungi is often accomplished by synergistic action of endo-and exo-glucanases [18]. These enzymes have received attention in many fields of science and biotechnology because many cultures of microorganisms widely used in industry produce 1,3-b-glucanases, which are essential for cell-cycle functions [19,20] and due to their increasing importance in modification of b-glucans for pharmaceutical purposes [21,22]. Despite a number of reports describing exo-1,3-b-glucanases from different sources [19,20,23 -25], the subsite structure of the substrate binding site as well as the affinity and the number of subsites have not been analyzed for most of these enzymes. The present study describes the isolation and characterization of an exo-1,3-bglucanase from the filamentous fungus Trichoderma viride AZ36. The subsite structure was evaluated by steady-state kinetics using 1,3-b-oligoglucosides with a different degree of polymerization. The mode of action and specificity as well as stereoselectivity of hydrolysis catalyzed by the exo-1,3-b-glucanase were studied by NMR spectroscopy. Abbreviations: DP, degree of polymerization; PHMB, p-hydroxymercuribenzoic acid sodium s...

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Section: Resultsmentioning

confidence: 99%

Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride

Kulminskaya

Thomsen

Shabalin

et al. 2001

European Journal of Biochemistry

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“…The mechanism of catalysis includes the degradation of cellobiose to glucose resulting in cellulose saccharification and release of the two enzymes from cellobiose inhibition [17, 18]. The enzymes are widely distributed in microbes, plants, and animals and play important roles in biological processes [19].…”

Section: Introductionmentioning

confidence: 99%

β-Glucosidases from the FungusTrichoderma: An Efficient Cellulase Machinery in Biotechnological Applications

Tiwari

Misra

Sangwan

2013

BioMed Research International

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β-glucosidases catalyze the selective cleavage of glucosidic linkages and are an important class of enzymes having significant prospects in industrial biotechnology. These are classified in family 1 and family 3 of glycosyl hydrolase family. β-glucosidases, particularly from the fungus Trichoderma, are widely recognized and used for the saccharification of cellulosic biomass for biofuel production. With the rising trends in energy crisis and depletion of fossil fuels, alternative strategies for renewable energy sources need to be developed. However, the major limitation accounts for low production of β-glucosidases by the hyper secretory strains of Trichoderma. In accordance with the increasing significance of β-glucosidases in commercial applications, the present review provides a detailed insight of the enzyme family, their classification, structural parameters, properties, and studies at the genomics and proteomics levels. Furthermore, the paper discusses the enhancement strategies employed for their utilization in biofuel generation. Therefore, β-glucosidases are prospective toolbox in bioethanol production, and in the near future, it might be successful in meeting the requirements of alternative renewable sources of energy.

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“…Based on the study of sub-site structure of A. niger beta-glucosidase [6], the reaction mechanism between oligomers and beta-glucanases in solution can be considered as: an oligomer which contains l glucose units can adsorb and be hydrolyzed by an beta-glucanase molecule into a glucose unit and an oligomer containing l−1 glucose unit(s). So the expression of R s (l)…”

Section: Oligomer Reactions With Beta-glucanasesmentioning

confidence: 99%

“…The specific activity and adsorption equilibrium coefficients of Endo-glucanase (EG1) and Exo-glucanases including Cellobiohydrolase I and II (CBH I and II) are from the work by Zhang and lynd [3]. For beta-glucanase (BG), the values of adsorption and kinetics parameters describing the reactions with oligomers are from the literature [6,11]. In the model, the values κ=1,2,3 and 4 represent EG1 CBH II CBH I and BG.…”

Section: Model Parametersmentioning

confidence: 99%

On Improved Mechanistic Modeling for Enzymatic Hydrolysis of Cellulose

Zhang

Zhou²

2014

J Chem Eng Process Technol

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An improved model for enzymatic hydrolysis of cellulose is developed that considers oligomer reactions with beta-glucanases, inhibition of oligomers to cellulases and enzyme decay processes during hydrolysis. Our oligomer reactions with beta-glucanases are modeled based on the enzymatic glucan chain fragmentation kinetics to describe the further fragmentation of oligomers in solution after being solubilized from the insoluble glucan chains. The inhibition effects on all cellulases by different types of cello-oligomers are then taken into account by competitive adsorption of cello-oligomers to the active site of cellulases, which is a critical factor contributing to the decrease in the rate of enzymatic hydrolysis of cellulose. As another factor affecting the kinetics of cellulose hydrolysis process, enzyme decay factor is incorporated into the model as the typical first order decay process. We consider two different processes for cellulases losing activity during hydrolysis in order to better understand the impact of enzyme decay on hydrolysis. Numerical simulation results are presented to investigate the phenomenon of hydrolysis rate slowdown commonly observed in experiments. Improvement of the predictive capability of the new model over previous one is clearly demonstrated by comparing the simulations with experimental data. By considering all the possible hydrolysis rate slowdown factors, the simulation results can agree with the experimental data very well, showing that our model is capable to fully capture the rate decrease of cellulose hydrolysis.

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Subsite structure of the β-glucosidase from Aspergillus niger, evaluated by steady-state kinetics with cello-oligosaccharides as substrates

Cited by 26 publications

References 32 publications

Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride

Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride

β-Glucosidases from the FungusTrichoderma: An Efficient Cellulase Machinery in Biotechnological Applications

On Improved Mechanistic Modeling for Enzymatic Hydrolysis of Cellulose

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Subsite structure of the β-glucosidase from Aspergillus niger, evaluated by steady-state kinetics with cello-oligosaccharides as substrates

Cited by 26 publications

References 32 publications

Isolation, enzymatic properties, and mode of action of an exo‐1,3‐β‐glucanase from T. viride

Isolation, enzymatic properties, and mode of action of an exo‐1,3‐β‐glucanase from T. viride

β-Glucosidases from the FungusTrichoderma: An Efficient Cellulase Machinery in Biotechnological Applications

On Improved Mechanistic Modeling for Enzymatic Hydrolysis of Cellulose

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Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride

Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride