Phototoxicity of protoporphyrin as related to its subcellular localization in mice livers after short-term feeding with griseofulvin.

The substrate specificities of three cellulases and a beta-glucosidase purified from Thermoascus aurantiacus were examined. All three cellulases partially degraded native cellulose. Cellulase I, but not cellulase II and cellulase III, readily hydrolyzed the mixed beta-1,3; beta-1,6-polysaccharides such as carboxymethyl-pachyman, yeast glucan and laminarin. Both cellulase I and the beta-glucosidase degraded xylan, and it is proposed that the xylanase activity is an inherent feature of these two enzymes. Lichenin (beta-1,4; beta-1,3) was degraded by all three cellulases. Cellulase II cannot degrade carboxymethyl-cellulose, and with filter paper as substrate the end product was cellobiose, which indicates that cellulase II is an exo-beta-1,4-glucan cellobiosylhydrolase. Degradation of cellulose (filter paper) can be catalysed independently by each of the three cellulases; there was no synergistic effect between any of the cellulases, and cellobiose was the principal product of degradation. The mode of action of one cellulase (cellulase III) was examined by using reduced cellulodextrins. The central linkages of the cellulodextrins were the preferred points of cleavage, which, with the rapid decrease in viscosity of carboxymethyl-cellulose, confirmed that cellulase III was an endocellulase. The rate of hydrolysis increased with chain length of the reduced cellulodextrins, and these kinetic data indicated that the specificity region of cellulase III was five or six glucose units in length.     

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.     

Purification and properties of the cellulases from the thermophilic fungus Thermoascus aurantiacus.

Three cellulases and a beta-glucosidase were purified from the culture filtrate of the thermophilic fungus Thermoascus aurantiacus. The isolated enzymes were all homogeneous on polyacrylamide-disc-gel electrophoresis. Data from chromatography on Bio-Gel P-60 and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis indicated mol.wts. of 87000 (beta-glucosidase), 78000 (cellulase I), 49000 (cellulase II) and 34000 (cellulase III); the carbohydrate contents of the enzymes were 33.0, 5.5, 2.6 and 1.8% (w/w) respectively. Although the three purified cellulases were active towards filter paper, only cellulases I and III were active towards CM(carboxymethyl)-cellulose. Cellulase I was also active towards yeast glucan. The Km and catalytic-centre-activity values for the enzymes were as follows; 0.52 mumol/ml and 6.5 X 10(4) for beta-glucosidase on p-nitrophenyl beta-D-glucoside, 3.9 mg/ml and 6.3 for cellulase I on CM-cellulose, 1.2 mg/ml and 1.1 for cellulase I on yeast glucan, 35.5 mg/ml and 0.34 for cellulase II on filter paper, and 1.9 mg/ml and 33 for cellulase III on CM-cellulose.     

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).     

Purification and properties of GM1 ganglioside beta-galactosidases from bovine brain

Two GM1-beta-galactosidases, beta-galactosidases I, and II, have been highly purified from bovine brain by procedures including acetone and butanol treatments, and chromatographies on Con A-Sepharose, PATG-Sepharose, and Sephadex G-200. beta-Galactosidase I was purified 30,000-fold and beta-galactosidase II 19,000-fold. Both enzymes appeared to be homogeneous, as judged from the results of polyacrylamide disc gel electrophoresis. Enzyme I had a molecular weight of 600,000-700,000 and enzyme II one of 68,000, as determined on gel filtration. On sodium dodecyl sulfate polyacrylamide slab gel electrophoresis under denaturing conditions, enzyme II gave a single band with a molecular weight of 62,000, while enzyme I gave two minor bands with molecular weights of 32,000 and 20,000 in addition to the major band at 62,000. Both enzymes liberated the terminal galactose from GM1 ganglioside and lactosylceramide but not from galactosylceramide. Enzyme I showed a pH optimum of 4.0 and was heat stable, while enzyme II showed a pH optimum of 5.0 and lost 50% of its activity in 15 min at 45 degrees C. Enzyme I showed a pI of 4.2 and enzyme II one of 5.9.     

Cellulase and cell differentiation in Acer pseudoplatanus

Summary Homogenates of differentiating xylem and phloem tissue have higher cellulase activities than cambial samples; the highest activity is always found in phloem. Callus tissue, in which no vascular differentiation occurs, contains only low cellulase activity. The results suggest that cellulase is involved in vascular differentiation. Different pH optima of cellulase activity were found: in cambium, xylem and phloem tissue, cellulase activity with an optimum at about pH 5.9 is predominantly membrane-bound; it is sedimentable at 100,000 g and releasable by Triton X-100. The same may be true of activity with an optimum at pH 5.3. Phloem tissue also contains a soluble, cytoplasmic cellulase of high activity at pH 7.1, and xylem tissue contains cytoplasmic cellulase with an optimum at pH 6.5. Low cellulase activity with a pH optimum similar to that of xylem homogenates was found in xylem sap. Cellulase activity in abscission zones increases greatly just before leaf abscission. Abscission zone cellulase has two pH optima, et 5.3 and 5.9; both activities are increased by Triton treatment of homogenates. The possible existence of several different cellulases forming part of a cellulase complex, and the rôle of the enzymes in hydrolysing wall material during cell differentiation are discussed.     

Cellulase Complex of the Fungus Chrysosporium lucknowense: Isolation and Characterization of Endoglucanases and Cellobiohydrolases

Using different chromatographic techniques, eight cellulolytic enzymes were isolated from the culture broth of a mutant strain of Chrysosporium lucknowense: six endoglucanases (EG: 25 kD, pI 4.0; 28 kD, pI 5.7; 44 kD, pI 6.0; 47 kD, pI 5.7; 51 kD, pI 4.8; 60 kD, pI 3.7) and two cellobiohydrolases (CBH I, 65 kD, pI 4.5; CBH II, 42 kD, pI 4.2). Some of the isolated cellulases were classified into known families of glycoside hydrolases: Cel6A (CBH II), Cel7A (CBH I), Cel12A (EG28), Cel45A (EG25). It was shown that EG44 and EG51 are two different forms of one enzyme. EG44 seems to be a catalytic module of an intact EG51 without a cellulose-binding module. All the enzymes had pH optimum of activity in the acidic range (at pH 4.5-6.0), whereas EG25 and EG47 retained 55-60% of the maximum activity at pH 8.5. Substrate specificity of the purified cellulases against carboxymethylcellulose (CMC), beta-glucan, Avicel, xylan, xyloglucan, laminarin, and p-nitrophenyl-beta-D-cellobioside was studied. EG44 and EG51 were characterized by the highest CMCase activity (59 and 52 U/mg protein). EG28 had the lowest CMCase activity (11 U/mg) amongst the endoglucanases; however, this enzyme displayed the highest activity against beta-glucan (125 U/mg). Only EG51 and CBH I were characterized by high adsorption ability on Avicel cellulose (98-99%). Kinetics of Avicel hydrolysis by the isolated cellulases in the presence of purified beta-glucosidase from Aspergillus japonicus was studied. The hydrolytic efficiency of cellulases (estimated as glucose yield after a 7-day reaction) decreased in the following order: CBH I, EG60, CBH II, EG51, EG47, EG25, EG28, EG44.     

Properties of acid beta-N-acetyl-D-glucosaminidase from cock semen.

Two forms (I and II) of beta-N-acetyl-D-glucosaminidase from cock seminal plasma and one form (III) from spermatozoa were separated by chromatofocusing. The active enzyme forms I and II had pI values of 6.6 and 6.3, respectively, while form III had two subforms with pI values of 6.3 and 6.1, as determined by polyacrylamide gel electrofocusing. The molecular weights were 76,000 for forms I and III and 32,000 for form II. The optimum pH of enzyme forms I and III ranged from 3.6 to 4.0. In contrast, form II showed one distinct maximum at pH 3.7. The Km values obtained with p-nitrophenyl-beta-N-acetyl-D-glucosaminide as substrate were 0.35, 0.28, and 0.39 mM for forms I, II, and III, respectively. It is assumed that both cock spermatozoa and cock seminal plasma contain a common, enzymatically active beta-N-acetyl-D-glucosaminidase subunit with M(r) about 32,000 and pI 6.3.     

Cellulase production by a thermophilic clostridium species

Strain M7, a thermophilic, anaerobic, terminally sporing bacterium (0.6 by 4.0 μm) was isolated from manure. It degraded filter paper in 1 to 2 days at 60 C in a minimal cellulose medium but was stimulated by yeast extract. It fermented a wide variety of sugars but produced cellulase only in cellulose or carboxymethyl-cellulose media. Cellulase synthesis not only was probably repressed by 0.4% glucose and 0.3% cellobiose, but also cellulase activity appeared to be inhibited by these sugars at these concentrations. Both C₁ cellulase (degrades native cellulose) and C_x cellulase (β-1,4-glucanase) activities in strain M7 cultures were assayed by measuring the liberation of reducing sugars with dinitrosalicylic acid. Both activities had optima at pH 6.5 and 67 C. One milliliter of a 48-h culture of strain M7 hydrolyzed 0.044-meq of glucose per min from cotton fibers. The cellulase(s) from strain M7 was extracellular, produced during exponential growth, but was not free in the growth medium until approximately 30% of the cellulose was hydrolyzed. Glucose and cellobiose were the major soluble products liberated from cellulose by the cellulase. ZnCl₂ precipitation appeared initially to be a good method for the concentration of cellulase activity, but subsequent purification was not successful. Isoelectric focusing indicated the presence of four C_x cellulases (pI 4.5, 6.3, 6.8, and 8.7). The rapid production and high activity of cellulases from this organism strongly support the basic premise that increased hydrolysis of native cellulose is possible at elevated temperature.     

Purification and characterization of acid beta-D-galactosidase from rabbit spleen

beta-D-Galactosidase has been purified to apparent homogeneity from rabbit spleen. The purification steps involved ammonium sulphate precipitation, DEAE-cellulose, concanavalin A-Sepharose, Sephadex G-200, and Sepharose 4B-(epsilon-aminocaproyl)-2-deoxy-beta-D-glucosylamine affinity chromatographies. In the DEAE-cellulose step, the beta-D-galactosidase was separated into two molecular forms, designated I and II, with similar pH optimum, Km, substrate specificity, and sensitivity to substrate analogues and other substances. Form I was purified 1,800-fold with a yield of about 2% of the total activity. This form is heat-labile, it has an acid optimal pH (4.0), an isoelectric point of 6.7 and a molecular weight of 75,000 daltons. Form II has an optimal pH of 3.6 and three different pI values (5.3, 5.7, and 6.7) whose relative proportions can be modified by treatment with neuraminidase. Form II appeared to be a multimeric form (IIA) of about 600,000 daltons at pH 4.0, which was reversibly dissociated to an oligomeric form (IIB) with an apparent molecular weight of 120,000 at neutral pH values. Both IIA and IIB were purified separately and showed an acid pH optimum and an heterogeneous pI (from 4.6 to 7.2). The dissociation of IIA into IIB can be generated spontaneously, but is increased by the presence of urea in the elution buffer, suggesting that both are aggregates of a common subunit.     

Mode of action of cellulases on dyed cotton with a reactive dye

Cotton woven fabrics which were previously dyed with a reactive dye were treated with a commercial cellulase preparation. Dyeing with a reactive dye for cotton apparently inhibited the weight loss activity and saccharification activity of cellulase. In addition, dyed cotton was treated with highly purified cellulases which were exo-type cellulases (Cellobiohydrolase I (CBH I) and Cellobiohydrolase II (CBH II)) and endo-type cellulase (Endoglucanase II (EG II)). Exo-type cellulases were inhibited more than endo-type cellulase by dyeing in the case of saccharification activity. CBH I was severely inhibited by dyeing as compared with CBH II or EG II from the viewpoint of morphological changes in the fiber surface. Dyes on the cellulose substrates severely influenced CBH I in spite of the rare modification, because CBH I hydrolyzed cellulose with true-processive action. The change in the activity of each cellulase component on dyed cotton can affect the synergistic action of cellulases.     

Some properties of starch phosphorylase from cotyledons of germinating seeds of Voandzeia subterranea.

Two isoenzymes (Forms I and II) of starch phosphorylase (1,4-alpha-D-glucan: orthophosphate alpha-glucosyltransferase, EC 2.4.1.1) were found in cotyledons of germinating seeds of Voandzeia subterranea L. Thouars. Phosphorylase I, which was the major component, had a pH optimum of 5.5--5.6, whereas phosphorylase II had a pH optimum of 6.1--6.3. Phosphorylase I had a molecular weight of 204 000 +/- 4000 and a subunit molecular weight of about 95 000. Phosphorylase I was stimulated by Mg2+, Mn2+, AMP, cyclic AMP, pyruvate and EDTA, but inhibited by Fe2+, Cu2+, Zn2+ and ATP. Stimulation of phosphorulase I by AMP was accompanied by changes in the affinity of the enzyme for glucose-1-phosphate in the presence of increasing AMP concentrations, and of AMP in the presence of increasing glucose-1-phosphate concentrations. Double-reciprocal plots of initial velocity data were non-linear (convex up) at low glucose-1-phosphate concentrations but became linear in the presence of AMP or ATP. Double-reciprocal plots were linear at high glucose-1-phosphate concentrations in the absence or presence of modifiers.     

Purification and biochemical characterization of glucose–cellobiose-tolerant cellulases from Scytalidium thermophilum

Two cellulases from Scytalidium thermophilum were purified and characterized, exhibiting tolerance to glucose and cellobiose. Characterization of purified cellulases I and II by mass spectrometry revealed primary structure similarities with an exoglucanase and an endoglucanase, respectively. Molecular masses were 51.2 and 45.6 kDa for cellulases I and II, respectively, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Cellulases I and II exhibited isoelectric points of 6.2 and 6.9 and saccharide contents of 11 and 93 %, respectively. Optima of temperature and pH were 60–65 °C and 4.0 for purified cellulase I and 65 °C and 6.5 for purified cellulase II. Both cellulases maintained total CMCase activity after 60 min at 60 °C. Cysteine, Mn²⁺, dithiotreitol and ß-mercaptoethanol-stimulated cellulases I and II. The tolerance to cellulose hydrolysis products and the high thermal stabilities of Scytalidium cellulases suggest good potential for industrial applications.     

Fractionation and characterization of cystine aminopeptidase (oxytocinase) and arylamidase of the human placenta.

Three activity peaks hydrolysing L-cystine-di-beta-naphthylamide (CysNA) and two activities hydrolysing L-leucine-beta-naphthylamide (LeuNA) were separated by gel filtration on Sepharose 6B from human placental tissue. The enzyme activities in the void volume and the solubilized enzyme activities with both substrates apparently are bound and free forms of the same enzymes (I) since detergent treatment caused a total disappearance of the activities in the void volume. The second distinct enzyme (II) was highly soluble and detected only with CysNA. The particle-bound enzyme(s) had a pH optimum at 6.5 with CysNA and at about 7.5 with LeuNA. They were highly sensitive to EDTA, could be reactivated by Co2+ and Zn2+ and were more sensitive to Ni2+ and L-methionine than the soluble enzyme II. The former enzyme(s) tolerated thermal treatment better than the soluble enzyme II. The solubilized free enzyme(s) I had a molecular weight of about 309,000. The soluble enzyme II was resistant to EDTA. Its optimum was at pH 6.0 and an estimate of 76,000 for the molecular weight was obtained.     

Screening of cellulases for biofuel production: online monitoring of the enzymatic hydrolysis of insoluble cellulose using high-throughput scattered light detection

A new prospective cellulase assay simultaneously combining high-throughput, online analysis and insoluble cellulosic substrates is described. The hydrolysis of three different insoluble cellulosic substrates, catalysed by a commercial cellulase preparation from Trichoderma reesei (Celluclast), was monitored using the BioLector - allowing online monitoring of scattered light intensities in a continuously shaken microtiter plate. Cellulase activities could be quantitatively assayed using the BioLector. At low cellulase/cellulose ratios, the Michaelis-Menten parameters of the cellulase mixture were mainly affected by the crystallinity index of the cellulose. Here, the apparent maximum cellulase activities inversely correlated with the crystallinity index of the cellulose. At high cellulase/cellulose ratios the particle size of the cellulose, defining the external surface area accessible to the cellulases, was the key determining factor for cellulase activity. The developed technique was also successfully applied to evaluate the pH optimum of cellulases. Moreover, the non-hydrolytic deagglomeration of cellulose particles was investigated, for the first time, using high-throughput scattered light detection. In conclusion, this cellulase assay ideally links high-throughput, online analysis and realistic insoluble cellulosic substrates in one simple system. It will considerably simplify and accelerate fundamental research on cellulase screening.     

CelS: a novel endoglucanase identified from Erwinia carotovora subsp. carotovora

A plasmid clone expressing a beta(1,4)-glucan glucanohydrolase (EC 3.2.1.4; endoglucanase) in Escherichia coli was isolated from a genomic library of Erwinia carotovora subsp. carotovora. The DNA segment carrying the corresponding structural gene, named celS, contained an open reading frame encoding a 264-amino acid (aa) polypeptide. The N-terminal aa sequence of CelS showed that the protein was synthesized with a 32-aa cleavable signal peptide. The mature 232-aa CelS had a calculated Mr of 26,228 and pI of 5.5. The pH optimum was about 6.8 and the temperature optimum was between 45 and 55 degrees C. Comparison of the aa sequence of CelS by hydrophobic cluster analysis with a range of cellulases and other quasi-isofunctional enzymes revealed only very limited sequence similarities, suggesting that the CelS protein may represent the first member of an additional cellulase family.     

Purification and physicochemical characterization of a human cytotoxic factor produced by a human haemic cell line.

A cytotoxic factor, produced by a human lymphoblastoid cell line [Karpas (1977) Br. J. Cancer 35, 152--160; Karpas (1977) Br. J. Cancer 36, 437--445], was purified both from the cell extracts and from the culture medium containing the cell lysate, by using ammonium sulphate precipitation, DEAE-cellulose chromatography, gel filtration and affinity chromatography on concanavalin A--Sepharose and on [3H]amino-ethanol--glass beads. Two factors, Factor I and Factor II, were separated by DEAE-cellulose chromatography. Factor I was eluted from this column at 30 mM-aminoethanol/HCl buffer, pH 8.0, whereas Factor II was bound strongly to DEAE-cellulose and was eluted only at 325 mM-aminoethanol/HCl buffer, pH 8.0. The purified Factor I migrated as a single band on polyacrylamide-gel electrophoresis. Its isoelectric point, pI, was 8.0 +/- 0.3. Its sedimentation coefficient, S20,w, was 3.5 +/- 0.1 S and its apparent molecular weight, Mr, was 65 000 +/- 1000 as determined by sedimentation-velocity and sedimentation-equilibrium measurements. A linear relationship between molecular weight and concentration was found in equilibrium runs, suggesting a non-spherical shape of the molecule. Factor I is not a glycoprotein, inasmuch as it does not bind to concanavalin A--Sepharose. It consists of two subunits (Mr 32 000 +/- 4000), migrating on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis as a single band. Factor II had pI 6.0 +/- 0.4 and Mr 75 000 +/- 3000. Factors I and II are thus different proteins.     

Purification and properties of cellulase from Phaseolus vulgaris

Cotyledons of germinating kidney beans contain two forms of a carboxy methyl cellulase which can be separated by ammonium sulfate fractionation and isoelectric focusing. The two cellulases are similar in their molecular weight but differ in isoelectric points, pH and temperature optimum, pH and temperature stability and sensitivity to thiol inhibitors and metal ions. One cellulase (isoelectric point 4.8) has been purified 100-fold to give a major protein band on acrylamide gel electrophoresis.     

pH-dependent adsorption of cellulases to protein-extracted lucerne fibres

The capacity of protein-extracted lucerne fibres to bind the cellulases of the mesophilic fungus Trichoderma reesei , and the thermophilic actinomycete Thermomonospora curvata , was determined to evaluate the fibre as a cellulase-recycling vehicle during bioconversion processes. Adsorption of fungal and bacterial cellulase complexes was minimal at the pH optima (5-0 and 6-2 respectively) for fibre conversion to soluble sugars. Lowering of incubation temperature to 3°C enhanced adsorption of fungal cellulases, but had no effect on bacterial cellulase adsorption. However, adsorptive capacity for either could be improved about 30% by raising the pH above the hydrolysis optimum during the recycling phase.     

Endo‐1,4‐β‐glucanase gene expression and cell wall hydrolase activities during abscission in Valencia orange

The physiological and molecular events of ethylene‐induced abscission in mature fruit calyx, laminar and floral abscission zones of cv. Valencia orange were examined. Continuous exposure of fruit explants to 5 µl 1⁻¹ ethylene for 2 to 40 h resulted in marked increases in endo‐1,4‐β‐glucanase (cellulase) and polygalacturonase (PG) activities in calyx abscission zones. Two abscission‐related cellulases and one PG were found. The major peak of cellulase activity corresponded to a pI of 8.0 and molecular weight of 51 kDa, whereas the minor cellulase peak had a pI of 5.5. The abscission polygalacturonase had a pI of 5.5. Calyx abscission zone RNA was amplified with degenerate primers based on sequence of the purified Valencia orange calyx abscission cellulase, and cloned. The two partial cellulase cDNA clones were 59% identical at the nucleotide level. Genomic Southern analysis suggested that Valencia orange contained two groups of cellulase genes. A full‐length cDNA clone from each group was isolated from a cDNA library prepared from ethylene‐induced calyx abscission zone mRNA. Both genes were expressed in ethylene‐induced calyx, laminar and floral abscission zones, but were not expressed in non‐induced abscission zones or mature leaves treated with or without ethylene, young bark or young fruit of Valencia.