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At least 19 recordsLinked to original sources
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↗
PubMed1977

Kinetics of the hydrolysis of cellobiose and p-nitrophenyl-beta-D-glucoside by cellobiase of Trichoderma viride.

Cellobiase has been isolated from the crude cellulase mixture of enzymes of Trichoderma viride using column chromatographic and ion-exchange methods. The steady-state kinetics of the hydrolysis of cellobiose have been investigated as a function of cellobiose and glucose concentrations, pH of the solution, temperature, and dielectric constant, using isopropanol-buffer mixtures. The results show that (i) there is a marked activation of the reaction by initial glucose concentrations of 4 X 10(-3) M to 9 X 10(-2) M and strong inhibition of the reaction at higher initial concentrations, (ii) the log rate -pH curve has a maximum at pH 5.2 and enzyme pK values of 3.5 and 6.8, (iii) the energy of activation at pH 5.1 is 10.2 kcal mol-1 over the temperature range 5-56 degrees C, and (iv) the rate decreases from 0 to 20% (v/v) isopropanol. The hydrolysis by cellobiase (EC 3.2.1.21) of p-nitrophenyl-beta-D-glucoside was examined by pre-steady-state methods in which [enzyme]0 greater than [substrate]0, and by steady-state methods as a function of pH and temperature. The results show (i) a value for k2 of 21 S-1 at pH 7.0 (where k2 is the rate constant for the second step in the assumed two-intermediate mechanism (formula: see text), (ii) a log rate -pH curve, significantly different from that for hydrolysis of cellobiose, in which the rate increases with decreasing pH below pH 4.5, is constant in the region pH 4.5-6, and decreases above pH 6 (exhibiting an enzyme pK value of 7.3), and (iii) an activation energy of 12.5 kcal mol-1 at pH 5.7 over the temperature range 10-60 degrees C.

Cellulase↗
PubMed2026

Hybrid genome assembly and phenotypic assays reveal carbohydrate metabolism diversity in Lacticaseibacillus strains.

Investigation of carbohydrate metabolism in lactic acid bacteria is essential for the rational selection of strains for fermentation processes, particularly in emerging applications involving non-conventional substrates or building of synthetic microbial consortia. However, establishing robust genotype-phenotype relationships remains challenging, as gene presence alone often fails to explain observed metabolic traits without considering the genomic context and regulatory architecture. In the present study, we combined hybrid genome assembly (Illumina and Oxford Nanopore) with high-throughput phenotype profiling (Biolog GENIII and PM2A) to investigate carbohydrate utilization in five Lacticaseibacillus strains. Phenotypic assays revealed clear intra- and inter-specific variability in substrate utilization. We therefore investigated whether such differences could be attributed to the organization and regulatory context of carbohydrate-associated loci, rather than to gene presence alone. Functional annotation based on COG and CAZyme databases revealed candidate genomic regions potentially involved in carbohydrate metabolism. Comparative analysis between predicted and experimentally observed substrate usage highlighted specific loci associated with carbohydrate utilization profile. The trehalose (tre) operon was conserved across all strains, while at least two distinct cellobiose-associated loci were detected in each genome. Despite the presence of these loci, L. paracasei strains were unable to metabolize cellobiose, a phenotype likely linked to the presence of a downstream TetR-type transcriptional repressor within the cellobiose (cel) operon. Additionally, a genomic region uniquely found in L. rhamnosus strains was associated with gentiobiose utilization, consistent with phenotypic observations. Overall, these findings highlight the importance of integrating phenotypic validation with complete genome context to support the identification of candidate structural and regulatory determinants of carbohydrate utilization in lactic acid bacteria. KEY POINTS: • Phenotype microarrays reveal metabolic traits of interest in isolated strains. • Regulatory context is key to understanding carbohydrate metabolism differences. • Basis of subspecies-dependent cellobiose metabolism in L. paracasei is provided.

Carbohydrate Metabolism↗
PubMed1975

Enzymatic studies on a cellulase system of Trichoderma viride. III. Transglycosylation properties of two cellulase components of random type.

Two highly purified cellulases [EC 3.2.1.4], II-A, and II-B, were obtained from the cellulase system of Trichoderma viride. Both cellulases split cellopentaose retaining the beta-configuration of the anomeric carbon atoms in the hydrolysis products at both pH 3.5 and 5.0. The Km values of cellulases II-A and II-B for cellotetraose were different, but their Vmax values were similar and those for cellooligosaccharides increased in parallel with chain length. Both cellulases produced predominantly cellobiose and glucose from various cellulosic substrates as well as from higher cellooligosaccharides. Cellulase II-A preferentially attacked the holoside linkage of rho-nitrophenyl beta-D-cellobioside, whereas cellulase II-B attacked mainly the aglycone linkage of this cellobioside. Both cellulases were found to catalyze the synthesis of cellotriose from rho-nitrophenyl beta-D-cellobioside by transfer of a glucosyl residue, possibly to cellobiose produced in the reaction mixture. They were also found to catalyze the rapid synthesis of cellotetraose from cellobiose, with accompanying formation of cellotriose and glucose, which seemed to be produced by secondary random hydrolysis of the cellotetraose produced. The capacity to synthesize cellotetraose from cellobiose appeared to be greater with cellulase II-B than with cellulase II-A.

Animals↗
PubMed1977

[beta-Glucosidases from fungus Geotrichum candidum].

beta-Glucosidases from Geotrichum candidum 3C cellulase preparation were separated from C1 enzymes and beta-1,4-glucanases by means of DEAE-Sephadex A-50 chromatography, gel filtration through P-150 Biogel and chromatography on CM-cellulose, and then were fractionated by isoelectric focusing using carrier ampholites with pH ranges 3-6 and 4-6. beta-Glucosidases with pI 3.8, 4.2, 4.6, 5.1, 5.6 and 6.2 were found in cellulase preparation from G. candidum 3C. Molecular weight of beta-glucosidases with pI 3.8, 4.2, 4.6 and 6.2, isolated under isoelectric focusing, were estimated by means of gel filtration through Sephadex G-200 to be 35000, 123000, 188000 and 223000 respectively. beta-Glucosidases with pI 3.8, 4.6, 5.6 and 6.2 hydrolyzed cellobiose and did not attack p-nitrophenyl-beta-D-glucopyranoside; those with pI 4.2 and 5.6 hydrolyzed p-nitrophenyl-beta-D-glucopyranoside and plant glucoside, protodioscin, and did not split cellobiose. All the beta-glucosidases studied did not hydrolyze laminaribose, beta-D-methylsylopyranoside, alder O-methylglucuronoxylane, o-nitrophenyl-beta-D-galactopyranoside and p-nitrophenyl-alpha-D-glucopyranoside. beta-Cellobiase with pI 6.2 hydrolzed lactoses, cellobioses with pI 3.8 and pI 5.6 splited gentiobiose. beta-Glucosidase with pI 4.6 did not attack any substrate studied, except cellobiose.

Cellulase↗
PubMed1979

The cellulolytic enzymes of Botryodiplodia theobromae Pat. Separation and characterization of cellulases and beta-glucosidases.

1. Filtrates from cultures of different ages of Botryodiplodia theobromae Pat. were fractionated by gel filtration, ion-exchange chromatography and polyacrylamide-gel electrophoresis. 2. Five cellulases (C1, C2, C3, C4 and C5) were found, and their molecular weights, estimated by gel filtration, were 46000-48000 (C1), 30000-35000 (C2), 15000-18000 (C3), 10000-11000 (C4) and 4800-5500 (C5). 3. Cellulase C5 was absent from old culture filtrates. 4. Cellulase C1 had little or no activity on CM-cellulose (viscometric assay), but degraded cotton flock and Whatman cellulose powder to give cellobiose only. 5. The other components (C2-C5) produced cellobiose and smaller amounts of glucose and cellotriose from cellulosic substrates and were more active in lowering the viscosity of CM-cellulose. 6. The ratio of activities assayed by viscometry and by the release of reducing sugars from CM-cellulose increased with decrease in the molecular weights of cellulases C2-C5. 7. Cellobiose inhibited the activities of the cellulases, but glucose stimulated at low concentrations although it inhibited at high concentrations. 8. A high-molecular-weight beta-glucosidase (component B1, mol.wt. 350000-380000) predominated in filtrates from young cultures, but a low-molecular-weight enzyme (B4, mol.wt. 45000-47000) predominated in older filtrates. 9. Intermediate molecular species of beta-glucosidase (B2, mol.wt. 170000-180000; B3, mol.wt. 83000-87000) were also found. 10. Cellulases C2-C5 acted in synergism with C1, particularly in the presence of beta-glucosidase.

Cellobiose↗
PubMed1977

Cellobiase from Trichoderma viride: purification, properties, kinetics, and mechanism.

Three distinct cellobiase components were isolated from a commercial Trichoderma viride cellulase preparation by repeated chromatography on DEAE cellulose eluting by a salt gradient. The purified cellobiase preparations were evaluated for physical properties, kinetics, and mechanism. Results from this work include: 1) development of one step enzyme purification procedure using DEAE-cellulose; 2) isolation of three chromatographically distinct, yet kinetically similar, cellobiase fractions of molecular weight of approximately 76,000; 3) determination of kinetics which shows that cellobiase hydrolyzes cellobiose by a noncompetitive mechanism and that the product, glucose, inhibits the enzyme, and 4) development of an equation, based on the mechanism of cellobiase action, which accurately predicts the time course of cellobiose hydrolysis over an eightfold range of substrate concentration and conversions of up to 90%. Based on the data presented in the paper, it is shown that product inhibition of cellobiase significantly retards the rate of cellobiose hydrolysis.

Disaccharides↗
PubMed1978

Enzymic activities of endo-1,4-beta-D-glucanases purified from Trichoderma viride.

Endoglucanases II, III and IV (EC 3.2.1.4) from Trichoderma viride are highly active in degrading CM-cellulose or phosphoric acid swollen cellulose, and only slightly active on Avicel. The specific activities of the endoglucanases increase with the length of the cellooligosaccharide substrates. By rate and product analyses using high pressure liquid chromatography the mode of action of Endoglucanase III was differentiated from that of Endoglucanases II and IV. Endoglucanase III has a low affinity for cellobiose, reacts rapidly with cellotriose, and gradually increases in reactivity with cellooligosaccharides as degree of polymerization increases from four to six. In addition to cleaving internal glycosidic bonds of polymeric substrates, it preferentially cleaves cellobiosyl units from the non-reducing end of oligosaccharides. The cellobiosyl units are often, under initial reaction conditions, transferred to the substrate-acceptor. Endoglucanases II and IV show a preference for internal glycosidic bonds of cellooligosaccharides. The soluble products from the initial action of Endoglucanases II and IV on swollen cellulose are glucose, cellobiose, and cellotriose, which are slowly converted to glucose and some cellobiose.

Cellulase↗
PubMed1976

Purification and properties of an endo-cellulase of avicelase type from Irpex lacteus (Polyporus tulipiferae).

A culture filtrate of Irpex lacteus (Polyporus tulipiferae) was fractionated initially by salting out with ammonium sulfate, and a cellulase [EC 3.2.1.4.] fraction with high Avicel-hydrolyzing activity (formerly called Avicelase) was extensively purified by a series of column chromatography procedures. This purified endo-cellulase showed a less random hydrolytic mechanism, and was obtained in a yield of 0.04% with respect to the starting material. Its specific activity was enhanced approximately 30 times over that of the starting material. The cellulase component showed a single peak on both ultracentrifugal and acrylamide disc electrophoretic analyses. Its molecular weight was estimated to be 56,000. It contained 12.2% carbohydrate; the major sugar constituents were glucose and mannose. Regarding the amino acid composition, the contents of aspartic acid and glycine were highest, followed by those of glutamic acid, serine, and theonine. The cellulase component was not markedly inhibited by most metal ions tested excepted for Hg2+. This purified endo-cellulase attacked a series of cellooligosaccharides, beta-cellobioside, CM-cellulose, and insoluble, cellulosic substrates. In the digests from insoluble substrates, glucose, cellobiose, cellotriose, and cellotetraose were detectable, but the amount of cellobiose was the largest by far. In constrast, cellobiose and glucose were produced in almost equal amounts from beta-cellobioside.

Amino Acids↗
PubMed1975

Sequential production of polygalacturonase, cellulase, and pectin lyase by Rhizoctonia solani.

The sequence of appearance of cell wall degrading enzymes of Rhizoctonia solani propagules was followed. Polygalacturonase (PG; EC 3.2.1.15) was induced earlier by sodium polypectate (NaPP) as compared with the induction of cellulase (Cx; EC 3.2.1.4) by carboxymethyl cellulose (CMC), cellobiose, or fibrous cellulose powder. Increasing CMC concentration to 0.5% shortened the time of Cx appearance. In Czapek medium containing citrus pectin, pectin lyase (PL; EC 4.2.2.10) was produced faster and at higher amounts than in a medium containing NaPP as the sole carbon source. PG appearance also preceded that of PL in media simultaneously supplemented with their respective inducers. NaPP, which induced production of PG, repressed Cx production. Among the Cx inducers, only CMC and cellobiose repressed PG production to any extent. At pH 6.0, either in a synthetic medium or on autoclaved bean hypocotyl segments, a delay in PG production as compared with Cx and Pl production was observed. Optimal pH levels for enzyme production and activity were 4.0 and 5.0 for PG, and 5.5 for Cx, and 8.0 and 7.5 for PL. PG was less repressed than Cx by glucose, cellobiose, and monogalacturonic acid, while PL was not affected.

Carboxymethylcellulose Sodium↗
PubMed2025

Cellodextrin Metabolism and Phosphotransferase System-Catalyzed Uptake in Enterococcus faecalis.

Two PTS transporters involved in the uptake of cellobiose and short cellooligosaccharides were identified in Enterococcus faecalis. Genes coding for the different EII proteins are found in a locus composed of three operonic structures expressing two distinct EIIC (CelC1 and CelC2), two identical EIIB (CelB1 and CelB2) and a unique EIIA (CelA1). The EIIA plays a central role in β-glucoside uptake because it is required not only for β-homodiholosides but also for the diheteroside N-acetylglucosamine-L-asparagine. Depending on their size, cellooligosaccharides are preferably transported either by CelC1 (di-saccharides) or by CelC2 (4 glycosidic residues and more), with tri-saccharides being taken up by both EIIC transporters. Moreover, CelA1B2C2 require CelGHI to be functional, three small proteins, the function of which remains unknown. CelA1B1C1 is the main but not exclusive transporter of cellobiose and chitobiose. It is involved in the transport of other β-glucodisaccharides, such as laminaribiose and sophorose. This PTS can be complemented by other transporters highlighting the existence of a network for β-glucoside uptake. This locus is under the control of CelR, a LevR-like transcription activator.

Enterococcus faecalis↗
PubMed1979

Enzymatic hydrolysis of cellulosic materials by Sclerotium rolfsii culture filtrate for sugar production.

The hydrolysis of purified celluloses (cotton, Avicel, Cellulose-123, Solka Floc SW40) and cellulosic wastes (rice straw, sugarcane bagasse, wood powders, paper factory effluents) by Sclerotium rolfsii CPC 142 culture filtrate was studied. Factors which effect saccharification such as pH, temperature, enzyme concentration, substrate concentration, produce inhibition, adsorption, and inactivation of enzyme and particle size were studied. Virtually no inhibition (less than 3%) of cellulose hydrolysis by the culture filtrate was observed by cellobiose and glucose up to 100 mg/mL. Filter paper degrading enzyme(s) (but neither carboxymethylcellulase nor beta-glucosidase) was adsorbed on cellulose. The n value in the S. rolfsii system was calculated to be 0.32 for Avicel P.H. 101 and 0.53 for alkali-treated (AT) rice straw indicating penetration of cellulase into AT rice straw. In batch experiments at 10% substrate level, solutions containing 6 to 7%, 3.8 to 4.7%, 4.0 to 5.1%, and 4.2 to 4.9% reducing sugars were produced in 24 to 48 from AT rice straw. AT bagasse, alkali - peracetic acid treated mesta wood and paper factory sedimented sludge effluent, respectively. The main constituent in the hydrolysate from cellulose was glucose with little or no cellobiose, probably due to the high cellobiase content in the culture filtrate.

Carbohydrates↗
PubMed1979

Cellulose degradation by a new isolate from sewage sludge, a member of the Bacteroidaceae family.

A mesophilic anaerobe, a member of the Bacteroidaceae family (NRC2248), isolated from a cellulose-enrichment culture, digested untreated Whatman cellulose powder and HCl-treated cotton battings while producing hydrogen, carbon dioxide, cellobiose, glucose, and acetic acid as the sole volatile acid. This organism also utilized cellobiose as carbon and energy source but did not utilize glucose. It grew well in synthetic medium containing ammonium salts as nitrogen source and having a pH value of 7.0-7.1 and an Eh value of -160mV or lower. The nutrient requirements of this organism were found to be similar to those of other anaerobes except for Na2S which inhibited cellulose degradation in concentrations above 0.75 mM. Best cellulose degradation occurred under an atmosphere of 80% N2-20% CO2. Use of H2 or 80% H2-20% CO2 as headspace gas inhibited growth. Although accumulation of acetic acid in about 15-16 mM concentrations inhibited the further formation of H2, CO2, and acetic acid in the broth, it did not stop the degradation of cellulose. The results indicate that this organism has the ability to grow in media containing up to 20 g/L of cellulose and to produce industrially important and easily separable end products from cellulose.

Acetates↗
PubMed1976

Enzymatic studies on a cellulase system of Trichoderma viride. IV. Purification and properties of a less-random type cellulase.

A cellulase [EC 3.2.1.4] component was purified from a crude cellulase preparation of Trichoderma viride (Meicelase) by consecutive column chromatography procedures, and was designated as cellulase III. The enzyme was homogeneous on polyacrylamide gel disc electrophoresis. The molecular weight of the enzyme was estimated to be about 45,000 by gel filtration. The optimum pH and temperature of the enzyme were pH 4.5-5.0 and 50 degrees, respectively. The enzyme was stable over the range of pH 4.5-7.5 at 4 degrees for 24 hr, and retained 40% of the original carboxymethylcellulose-saccharifying activity after heating at 100 degrees for 10 min. The enzyme was completely inactivated by 1 mM Hg2+, and partially by 1 mM Ag+ and Cu2+. The enzyme was characterized as a less-random type cellulase on the basis of its action on carboxymethylcellulose. The enzyme split cellohexaose, retaining the beta-configuration of the anomeric carbon atoms in the hydrolysis products. The Km values of cellulase III for cellooligosaccharides decreased in parallel with increase of the chain length of the substrates, while Vmax values showed a tendency to increase. The enzyme produced predominantly cellobiose and glucose from various cellulosic substrates as well as from higher cellooligosaccharides. Cellulase III preferentially attacked the aglycone linkage of p-nitrophenyl beta-D-cellobioside. The enzyme was found to catalyze the rapid synthesis of cellotetraose from cellobiose (condensation action).

Carboxymethylcellulose Sodium↗
PubMed1978

Purification and properties of an exo-cellulase of Avicelase type from a wood-rotting fungus, Irpex lacteus (Polyporus tulipiferae).

A cellulase component of Avicelase type was obtained from Driselase, a commercial enzyme preparation from a wood-rotting fungus Irpex lacteus (Polyporus tulipiferae). It showed a single band on SDS-polyacrylamide electrophoresis. The amino acid composition of this cellulase resembled those of cellulase components of endo-type from the same fungus. However, it produced exclusively cellobiose from CMC as well as from water-insoluble celluloses such as Avicel or cotton at earlier stages of hydrolysis. In addition, the hydrolysis of CMC practically stopped after an initial rapid stage. The cellulase showed a strong synergistic action with an endo-cellulase of higher randomness (typical CMCase-type) in the hydrolysis of CMC as well as Avicel. In contrast to cellotriose and -tetraose, cellopentaose and -hexaose were attacked very rapidly, and only cellobiose was produced. These results suggest that the cellulase is an exo-type component. However, it mutarotated the products from cellopentaitol in the same direction as endo-cellulases. it represented a relatively large portion of the total cellulase activity, and may play an important role in the degradation of native cellulose in vivo.

Amino Acids↗
PubMed1977

Control of beta-glucosidase synthesis in Mucor racemosus.

The beta-glucosidase of Mucor racemosus was shown to be synthesized when the organism was grown in the presence of such diverse carbon sources as glycerol, lactate, xylose, ribose, alpha-methylglucoside, alpha-phenylglucoside, maltose, and cellobiose. Enzyme synthesis was strongly repressed in the presence of hexoses. In addition, exogenous cyclic adenosine 3',5'-monophosphate (cAMP) resulted in enzyme repression. When cAMP was added exogenously after enzyme activity had accumulated, a reversible enzyme inactivation occurred. Growth on disaccharides (maltose or cellobiose) was severely retarded in the presence of cAMP, whereas that on glucose remained unaffected. The results indicate a probable role for cAMP in control of glucosidase synthesis in Mucor.

Carbon↗