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PubMedDate not supplied

[Purification of lectin from perch (Persa fluviatilis L.) roe specific to cellobiose and study of its characteristics].

Two lectins with different carbohydrate specificity were purified from perch (Persa fluviatilis L.) roe (coastal ecological form) by affinity chromatography on ovariomucine H-sepharose from a human ovary cyst. One lectin was eluted by cellobiose and another lectin was eluted by L-fucose. The L-fucose-specific lectin interacted only with L-fucose and its derivatives, but did not interact with cellobiose and salicin. The cellobiose-specific lectin interacted with all the examined carbohydrates, but cellobiose was the best inhibitor. This lectin can be also purified on cellulose as an affinity sorbent. Unlike the L-fucose-specific lectin from perch roe, the cellobiose-specific lectin is less soluble in water-saline solutions. Lectin solubility increases greatly in presence of specific inhibitors, cellobiose, in particular. L-fucose, alpha-methyl-L-fucopyranoside and 4-nitrophenyl-alpha-L-fucopyranoside are equivalent inhibitors for both lectins. According to SDS-PAGE data, the lectins contain two components with molecular weight 12-13 kDa. In solutions, these components form molecules with 50 or 100 kDa (depending on pH). Data obtained from electrophoresis in PAAG in alkaline (pH 8.9) and acidic system (pH 4.3), and SDS-PAGE did not display essential distinctions between these both lectins.

Acrylic Resins↗

PubMed1979

[Cellobiose as a regulator of endoglucanase activity of cellulase complexes. Mechanism of the regulation].

Cellobiose may exert different effects on the activities of various endoglucanases. The endoglucanases of T. reesei and Rapidase are noticeably suppressed by cellobiose at concentrations above 3 mM. On the other hand, a low molecular weight endoglucanase from T. koningii is activated by cellobiose, whereas high molecular weight endoglucanases from the same source are inhibited by cellobiose. A detailed kinetic analysis of the effects showed that the low molecular weight endoglucanase is activated by a transglycosylation mechanism, in which cellobiose acts as an additional nucleophile. At saturating concentrations of cellobiose (Ks = 15 mM) the enzyme activity is increased 6-fold. Such a specific mechanism of activation manifests itself in an acceleration of random cleavage of CM-cellulose by the low molecular weight endoglucanase, which can be recorded by a viscosimetric technique. However, its action does not accelerate the production of soluble reducing sugars.

Cellobiose↗

PubMed1993

Purification and characterization of cellobiose dehydrogenase, a novel extracellular hemoflavoenzyme from the white-rot fungus Phanerochaete chrysosporium.

Cellobiose dehydrogenase (CDH), an extracellular hemoflavoenzyme produced by the cellulose-degrading cultures of Phanerochaete chrysosporium, oxidizes cellobiose to cellobionolactone. CDH has been purified to homogeneity by a five-step purification procedure. The homogeneous CDH is monomeric and has a relative molecular mass of 90,000. It is also a glycoprotein with a neutral carbohydrate content of 9.4%. Purified CDH contains one heme b and one flavin adenine dinucleotide per monomer. Homogeneous CDH has a specific activity of 10.3 mumol min-1 mg-1 for cytochrome c reduction, in the presence of cellobiose. Cellotriose, cellotetraose, cellopentaose, and lactose also serve as substrates for CDH, in addition to cellobiose. Cytochrome c, dichlorophenol-indophenol, Mn3+, and benzoquinones can function as electron acceptors in these oxidations. Kinetic studies suggest that cellobiose is the preferred substrate and cytochrome c is the preferred electron acceptor. In the absence of these electron acceptors, oxygen serves as a poor electron acceptor and is reduced to H2O2. CDH is very stable in the pH range 3-10 and up to 50 degrees C. At lower pH or at higher temperature, CDH is inactivated due to the release of flavin from the active site. The native ferric form of the enzyme has absorption maxima at 420, 529, and 570 nm. With the addition of cellobiose, these absorptions shift to 428, 534, and 564 nm. The ferric enzyme does not bind azide or cyanide, implying that the heme iron is probably hexacoordinate.

Agaricales↗

PubMed2004

Differential transcription of beta-glucosidase and cellobiose dehydrogenase genes in cellulose degradation by the basidiomycete Phanerochaete chrysosporium.

Transcriptional analysis of beta-glucosidase gene (bgl) and cellobiose dehydrogenase gene (cdh) in relation to cellobiose metabolism in the basidiomycete Phanerochaete chrysosporium was performed using real-time quantitative RT-PCR. Addition of glucose to cellulose-degrading culture significantly decreased the number of both transcripts. In contrast, addition of cellobiose repressed only transcription of bgl but no effect for that of cdh. Moreover, to investigate induction of the two genes, the mycelia grown on glucose medium were transferred to medium containing glucose, cellobiose or no carbon source. In cellobiose medium, the number of bgl transcripts was slightly lower, whereas that of cdh transcripts was 2.3-fold higher than those in glucose medium. Consequently, cellobiose represses transcription of bgl, whereas it induces that of cdh.

Carbohydrate Dehydrogenases↗

PubMed1985

Some properties of cellobiose oxidase from the white-rot fungus Sporotrichum pulverulentum.

Cellobiose oxidase from the white-rot fungus Sporotrichum pulverulentum has been purified to homogeneity by a new procedure. The carbohydrate and amino acid compositions of the enzyme have been determined. Cellobiose oxidase contains FAD and cytochrome b prosthetic groups. Mr of the enzyme has been estimated at 74400 by sedimentation equilibrium. The enzyme is a monomer. Optical, fluorescence and e.p.r. spectra of oxidized and reduced cellobiose oxidase have been determined. A preliminary investigation of the substrate specificity of cellobiose oxidase reveals that disaccharides and even some insoluble polysaccharides are substrates, but not monosaccharides. Strong substrate inhibition is seen at high concentrations of cellobiose. This effect is particularly marked when oxygen is the electron acceptor. Cellobiose oxidase is unusual among flavoproteins, since it stabilizes the red anionic flavin semiquinone and forms a sulphite adduct, yet appears to produce the superoxide anion as its primary reduced oxygen product.

Amino Acids↗

PubMed2002

Characterization of a cellobiose phosphorylase from a hyperthermophilic eubacterium, Thermotoga maritima MSB8.

The cepA putative gene encoding a cellobiose phosphorylase of Thermotoga maritima MSB8 was cloned, expressed in Escherichia coli BL21-codonplus-RIL and characterized in detail. The maximal enzyme activity was observed at pH 6.2 and 80 degrees C. The energy of activation was 74 kJ/mol. The enzyme was stable for 30 min at 70 degrees C in the pH range of 6-8. The enzyme phosphorolyzed cellobiose in an random-ordered bi bi mechanism with the random binding of cellobiose and phosphate followed by the ordered release of D-glucose and alpha-D-glucose-1-phosphate. The Km for cellobiose and phosphate were 0.29 and 0.15 mM respectively, and the kcat was 5.4 s(-1). In the synthetic reaction, D-glucose, D-mannose, 2-deoxy-D-glucose, D-glucosamine, D-xylose, and 6-deoxy-D-glucose were found to act as glucosyl acceptors. Methyl-beta-D-glucoside also acted as a substrate for the enzyme and is reported here for the first time as a substrate for cellobiose phosphorylases. D-Xylose had the highest (40 s(-1)) kcat followed by 6-deoxy-D-glucose (17 s(-1)) and 2-deoxy-D-glucose (16 s(-1)). The natural substrate, D-glucose with the kcat of 8.0 s(-1) had the highest (1.1 x 10(4) M(-1) s(-1)) kcat/Km compared with other glucosyl acceptors. D-Glucose, a substrate of cellobiose phosphorylase, acted as a competitive inhibitor of the other substrate, alpha-D-glucose-1-phosphate, at higher concentrations.

Enzyme Stability↗

PubMedDate not supplied

[Degradation of lignin-carbohydrate substrate by soil fungi--producers of laccase and cellobiose dehydrogenase].

The growth of nonsporulating mycelial fungi INBI 2-26(+), producer of laccase; INBI 2-26(-), producer of cellobiose dehydrogenase; and their mixed culture on lignin-carbohydrate substrates under conditions of submerged fermentation were studied. The degrees of degradation of lignin, cellulose, and hemicellulose of cut straw over 23 days amounted to 29.8, 51.4, and 72% for the laccase producer; 15.8, 33.9, and 59.1% for the cellobiose dehydrogenase producer; and 15.8, 39.4, and 64.5% for the mixed culture, respectively. The laccase activity in the medium when strain 2-26(+) was cultivated individually reached its maximum on day 28; the activity of cellobiose dehydrogenase of strain 2-26(-), on days 14 to 28. A method for determining cellobiose dehydrogenase activity in the presence of laccase was developed. In the mixed culture, both enzymes were formed; however, the level of laccase synthesis was 1.5-fold lower compared to that of strain 2-26(+), while synthesis of cellobiose dehydrogenase was similar to that of the corresponding producer. Cellobiose dehydrogenase failed to boost the action of laccase while degrading the lignin of straw.

Carbohydrate Dehydrogenases↗

PubMed1999

Effect of dilution rate, cellobiose and ammonium availabilities on Clostridium cellulolyticum sporulation.

The nutritional and physiological factors affecting sporulation of Clostridium cellulolyticum were studied using steady-state continuous cultures grown in both complex and synthetic media. Under cellobiose limitation, the probability that cells will sporulate appears to be directly related to the growth rate. In complex medium, the highest percentage of sporulation was 20% at a dilution rate of 0.015 h-1 whereas in synthetic medium it was 10% at 0.035 h-1. In both media, when the dilution rate was either higher or lower the percentage of sporulation decreased by between 2% and 4%. At low dilution rates, endospore formation was repressed under cellobiose-sufficient concentrations, suggesting catabolite repression by cellobiose. Furthermore, the concentration of ammonium was important in determining the percentage of sporulation, as ammonium limitation induced extensive sporulation at low growth rates even in an excess of cellobiose. The sporulation process is not triggered when cells are cellobiose-exhausted both in complex and synthetic media. These data suggest that, in C. cellulolyticum, an exogenous supply of carbon is required throughout the sporulation process. In the experimental conditions used in this work, no relationship between glycogen accumulation or glycogen mobilization and endospore formation was detected in C. cellulolyticum.

Biomass↗

PubMed2006

Phosphorylase coupling as a tool to convert cellobiose into amylose.

This work aims to establish the enzymatic process to produce amylose from cellobiose. Incubation of cellobiose with cellobiose phosphorylase and alpha-glucan phosphorylase in the presence of maltotetraose and a catalytic amount of inorganic phosphate at 45 degrees C for 16 h resulted in the production of linear alpha-1,4-glucan with a 19.3% (w/v, against cellobiose weight) yield. The yield was successfully improved (32.4%) when mutarotase and glucose oxidase were added to remove glucose in the reaction mixture. The weight-average molecular weight of the product was precisely controlled from 42 to 720 kDa by changing the initial molar ratio of cellobiose to maltotetraose. The combined use of two different phosphorylases should be a useful tool in converting beta-1,4-linked-polysaccharide into alpha-1,4-linked-polysaccharide.

Amylose↗

PubMed2002

A DFT/ab initio study of hydrogen bonding and conformational preference in model cellobiose analogs using B3LYP/6-311++G**.

A series of beta-cellobiose analogs were studied at the B3LYP/6-311++G** level of theory to isolate and understand how the various electronic components of the beta-(1-->4)-linked disaccharide, cellobiose, contribute to the energetic stability of the molecule in vacuo. Previous studies on beta-cellobiose (see accompanying paper) showed that the most energetically stable conformation was that in which the dihedral angle phi (phi(H)) was 'flipped' by approximately 180 degrees relative to the 'normal' form. From our examination of eight sets of structures in which different combinations of functional hydroxyl and hydroxymethyl groups were removed, it was determined that only beta-cellobiose and one other analog (analog 7, beta-xylobioside), an analog in which both hydroxymethyl groups were removed but the exocyclic hydroxyl groups retained, can form a 'cooperative' hydrogen-bonding network. Only in these two molecules did we find continuous synergistic 'communication' through hydrogen bonding from one sugar moiety to the other. This 'cooperative' hydrogen bonding energetically stabilizes the 'flipped' conformation of beta-cellobiose and beta-xylobioside, while the other analogs studied were unable to form a 'cooperative' grouping of hydrogen bonds and thus were more stable in their 'normal' conformational state.

Carbohydrate Conformation↗

PubMed1987

Biochemical genetics of the cryptic gene system for cellobiose utilization in Escherichia coli K12.

The cellobiose catabolic system of Escherichia coli K12 is being used to study the role of cryptic genes in microbial evolution. Wild-type E. coli K12 do not utilize the beta-glucoside sugars, arbutin, salicin and cellobiose. A Cel+ (cellobiose utilizing) mutant which grows on cellobiose, arbutin, and salicin was isolated previously from wild-type E. coli K12. Biochemical assays indicate that a cel structural gene (celT) specifies a single transport protein that is a beta-glucoside specific enzyme of the phosphoenolpyruvate-dependent phosphotransferase system. The transport protein phosphorylates beta-glucosides at the expense of phosphoenolpyruvate. A single phosphoglucosidase, specified by celH, hydrolyzes phosphorylated cellobiose, arbutin, and salicin. The genes of the cel system are expressed constitutively in the Cel+ mutant, whereas they are not expressed at a detectable level in the wild-type strain. The transport and hydrolase genes are simultaneously silenced or simultaneously expressed and thus constitute an operon. Cel+ strains which fail to utilize one or more beta-glucosides express the transport system at a lower level than do Cel+ strains which grow on all three beta-glucosides. Other strains inducibly express a gene which specifies transport of arbutin but not the other beta-glucosides. The arbutin transport gene, arbT, maps outside of the cel locus.

Bacterial Proteins↗

PubMed1992

Evidence that cellobiose oxidase from Phanerochaete chrysosporium is primarily an Fe(III) reductase. Kinetic comparison with neutrophil NADPH oxidase and yeast flavocytochrome b2.

Kinetic measurements were made for purified cellobiose oxidase in 100 mM acetate (pH 4.0) at 30 degrees C, with excess cellobiose as substrate and O2 or Fe(III) as acceptor. With O2 at 230 microM as sole electron acceptor, the O2 uptake rate corresponded to a one-electron turnover number of 0.13 +/- 0.01 s-1. Measurements at different O2 concentrations indicated Km(O2) greater than 120 microM. In separate experiments, the reduction of Fe(III) acetate was monitored at 340 nm in the absence of oxygen. The maximum velocity of Fe(III)-acetate reduction (Vmax) was 4.5 +/- 0.7 s-1, while Km[Fe(III) acetate] was 34 +/- 12 microM. With ferricyanide in place of Fe(III) acetate, the corresponding values were 6.9 +/- 0.7 s-1 and 23 +/- 5 microM. Redox titrations established the potential of the haem prosthetic group of the oxidase at pH 4.0 as +165 mV. The midpoint potential for Fe(III)/Fe(II) acetate at pH 4.0 is much higher, a value of +535 mV being obtained with 200 microM Fe. Cellobiose oxidase resembles yeast flavocytochrome b2 and differs from the neutrophil NADPH oxidase in having the potential of its haem group far above the potential for one-electron reduction of O2 to superoxide (Em,4 = -110 mV). A kinetic comparison led to the conclusion that the role of cellobiose oxidase is as an Fe(III) reductase. Fe(II) may have a biological importance as a component of Fenton's reagent [Fe(II)/H2O2]. The concentration of cellobiose oxidase in the growth medium at harvest (0.3 microM) can provide a far higher flux of Fe(II) than a non-enzymic proposal in the literature.

Basidiomycota↗

PubMed1996

Simultaneous but differential metabolism of glucose and cellobiose in Fibrobacter succinogenes cells, studied by in vivo 13C-NMR.

Kinetics of [1-13C]glucose utilization were monitored by in vivo NMR spectroscopy on resting cells of Fibrobacter succinogenes, in the presence of 32 mM [1-13C]glucose, 32 mM [1-13C]glucose and 64 mM unlabelled glucose, or 32 mM [1-13C]glucose and 32 mM unlabelled cellobiose. A similar production of acetate and succinate and a similar storage of glycogen were observed whatever the exogenous substrate. The presence of cellobiose or that of an equivalent amount of glucose did not reduce [1-13C]glucose incorporation to the same extent. Glucose seemed preferentially used for glycogen storage and energy production, while part of the cellobiose appeared to be used for cellodextrin synthesis. Both cellobiase and cellobiose phosphorylase activities were assayed in cell-free extracts. Finally, the intracellular concentration of glucose 6-phosphate was increased by over threefold when cells metabolized cellobiose (alone or in parallel to glucose) as compared with the metabolism of glucose alone.

Acetates↗

PubMed2004

Mechanism of cellobiose inhibition in cellulose hydrolysis by cellobiohydrolase.

An experimental study of cellobiose inhibition in cellulose hydrolysis by synergism of cellobiohydrolyse I and endoglucanase I is presented. Cellobiose is the structural unit of cellulose molecules and also the main product in enzymatic hydrolysis of cellulose. It has been identified that cellobiose can strongly inhibit hydrolysis reaction of cellulase, whereas it has no effect on the adsorption of cellulase on cellulose surface. The experimental data of FT-IR spectra, fluorescence spectrum and circular dichroism suggested that cellobiose can be combined with tryptophan residue located near the active site of cellobiohydrolase and then form steric hindrance, which prevents cellulose molecule chains from diffusing into active site of cellulase. In addition, the molecular conformation of cellobiohydrolase changes after cellobiose binding, which also causes most of the non-productive adsorption. Under these conditions, microfibrils cannot be separated from cellulose chains, thus further hydrolysis of cellulose can hardly proceed.

Carbohydrate Conformation↗

PubMed2004

Effect of Lactobacillus rhamnosus KY-3 and cellobiose as synbiotics on lipid metabolism in rats.

Lactobacillus rhamnosus KY-3 is a fermentative bacterium that is used for the industrial production of L-lactic acid. We have examined the effect of L. rhamnosus KY-3 and cellobiose as synbiotics on lipid metabolism in rats. Rats were fed on a 20% casein diet (C) supplemented with either 1.7% L. rhamnosus KY-3 (KY-3), 10% cellobiose (CEB), or 1.7% L. rhamnosus KY-3 and 10% cellobiose (KY-3+CEB) for 13 d. The concentrations of serum total lipids, triacylglycerol, total cholesterol, and phospholipids were significantly reduced in rats fed a KY-3+CEB diet in comparison to those on the C, KY-3 and CEB diets. There was an increase in the weight of cecal contents and a significant increase in the amount of cecal short-chain fatty acids (SCFA). The dry weight of excretion increased additively upon the simultaneous administration of L. rhamnosus KY-3 and cellobiose (KY-3 + CEB). The amount of excreted fecal bile acids did not differ among the groups in this study. These findings support the hypothesis that the promotion of cecal fermentation can lower the level of serum lipids. These results suggest that simultaneous administration of L. rhamnosus KY-3 and cellobiose as synbiotics has a beneficial effect on lipid metabolism.

Animals↗

PubMed1990

[Use of glucose and cellobiose by 3 strains of Fibrobacter succinogenes].

F succinogenes strains S85, 128 and 095 were compared with respect to their growth using glucose and/or cellobiose as the carbon and energy substrate(s) and their capacities to degrade cellulose. The growth rate of F succinogenes strain S85 was the same using glucose or cellobiose, whereas the growth rates of strains 128 and 095 were about thrice the rate when using cellobiose. Strain S85 could simultaneously use glucose and cellobiose, while strains 128 and 095 tended to use preferentially glucose then cellobiose in a mixture of the 2 sugars. Their capacities to degrade cellulose were equivalent.

Animals↗

PubMed2004

Ancestral gene fusion in cellobiose dehydrogenases reflects a specific evolution of GMC oxidoreductases in fungi.

Cellobiose dehydrogenases (CDHs) are extracellular hemoflavoenzymes that are thought to be involved in the degradation of two of the most abundant biopolymers in the biosphere, cellulose and lignin. To date, these enzymes, consisting of a cytochrome domain and a flavin domain, have been detected and sequenced exclusively in the kingdom of fungi. Independent phylogenetic analyses of two distinct domains of CDH genes reveal that they evolved in parallel as fused genes. Whereas the cytochrome domains are unique sequence motifs, the flavin domains clearly belong to the glucose-methanol-choline (GMC) oxidoreductase family--an evolution line of widespread flavoproteins extending from the Archae to higher eukaryotes. The most probable unrooted phylogenetic tree obtained from our analysis of 52 selected GMC members reveals five principal evolutionary branches: cellobiose dehydrogenase, cholesterol oxidase (COX), hydroxynitrile lyase, alcohol oxidase (AOX)/glucose oxidase (GOX)/choline dehydrogenase, and a branch of dehydrogenases with various specificities containing also an Archaeon open reading frame (ORF). Cellobiose dehydrogenases cluster with cholesterol oxidases and the clade of various specificities, whereas hydroxynitrile lyases are closely related to glucose oxidases, alcohol oxidases, and choline dehydrogenases. The results indicate that the evolutionary line from a primordial GMC flavoprotein to extant cellobiose dehydrogenases was augmented after an early acquisition of the cytochrome domain to form two distinct branches for basidiomycetes and ascomycetes. One ascomycetous evolutionary line of CDHs has acquired a carbohydrate-binding module (CBM) of type 1, the sequence of which is similar to that of corresponding domains in several glycosidases. This is the first attempt towards a comprehensive phylogenetic analysis of cellobiose dehydrogenases.

Alcohol Oxidoreductases↗

PubMed2006

Structural dissection of the reaction mechanism of cellobiose phosphorylase.

Cellobiose phosphorylase, a member of the glycoside hydrolase family 94, catalyses the reversible phosphorolysis of cellobiose into alpha-D-glucose 1-phosphate and D-glucose with inversion of the anomeric configuration. The substrate specificity and reaction mechanism of cellobiose phosphorylase from Cellvibrio gilvus have been investigated in detail. We have determined the crystal structure of the glucose-sulphate and glucose-phosphate complexes of this enzyme at a maximal resolution of 2.0 A (1 A=0.1 nm). The phosphate ion is strongly held through several hydrogen bonds, and the configuration appears to be suitable for direct nucleophilic attack to an anomeric centre. Structural features around the sugar-donor and sugar-acceptor sites were consistent with the results of extensive kinetic studies. When we compared this structure with that of homologous chitobiose phosphorylase, we identified key residues for substrate discrimination between glucose and N-acetylglucosamine in both the sugar-donor and sugar-acceptor sites. We found that the active site pocket of cellobiose phosphorylase was covered by an additional loop, indicating that some conformational change is required upon substrate binding. Information on the three-dimensional structure of cellobiose phosphorylase will facilitate engineering of this enzyme, the application of which to practical oligosaccharide synthesis has already been established.

Binding Sites↗