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1.
A wall-bound endo-1,4-ß-glucanase (EC 3.2.1.4 [EC] ) wasobtained from a preparation of the cell walls of suspension-culturedpoplar cells and purified to electrophoretic homogeneity bycation-exchange, hydrophobic, and gel-filtration chromatography.The molecular mass was estimated to be 47 kDa by SDS-PAGE and48 kDa by gel filtration on Superdex 200 pg. The isoelectricpoint (pI) was 5.6. The purified enzyme catalyzed the endo-hydrolysisof carboxymethylcellulose with an optimal pH of 6.5, a Km of1.2 mg ml-1, and a Vmax of 280 units. The purified enzyme specificallyhydrolyzed the 1,4-ß-glucosyl linkages of carboxymethylcellulose,phospho-swollen cellulose, lichenan, xylan and xyloglucan. Theactivity of the enzyme was strongly stimulated by cysteine-HCl.The N-terminal sequence of the enzyme was similar to that ofan extracellular endo-1,4-ß-glucanase found in suspensioncultures of poplar cells and some homology was recognized toavocado fruit-ripening and bean abscission endo-1,4-ß-glucanases. 1This work was supported in part by a grant from the Toray ScienceFoundation, Japan, and by a Grant-in-Aid from the Ministry ofEducation, Science and Culture of Japan.  相似文献   

2.
3.
An endo-1,4-rß-glucanase (EC 3.2.1.4 [EC] ) was purifiedto apparent homogeneity from the culture medium of poplar (Populusalba L.) cells by sequential anion-exchange, hydrophobic, andgel-filtration chromatography. The preparation of extracellularrß-glucanase was homogeneous on SDS-polyacrylamidegel electrophoresis (PAGE) and native PAGE. The molecular weight,as determined by SDS-PAGE was 50,000, whereas that determinedby gel filtration was 40,000. The isoelectric point (pI) was5.5. The purified enzyme catalyzed the endohydrolysis of carboxy-methylcellulosewith a pH optimum of 6.0 and a km of 1.0 mg ml–1. Theenzyme specifically cleaved the 1,4-rß-glucosyl linkagesof carboxymethylcellulose, swollen cellulose, lichenan and xyloglucan,although the last was hydrolyzed more slowly than the othertested substrates. The activity of the endo-1,4-rß-glucanaseincreased up to the early stage of the mid-logarithmic phaseof growth and then decreased rapidly, suggesting that the rß-glucanaseis induced before cell development. (Received April 28, 1993; Accepted July 19, 1993)  相似文献   

4.
Formation and location of 1,4-β-glucanases and 1,4-β-glucosidases were studied in cultures of Penicillium janthinellum grown on Avicel, sodium carboxymethyl cellulose, cellobiose, glucose, mannose, and maltose. Endo-1,4-β-glucanases were found to be cell free, and their formation was induced by cellobiose. 1,4-β-Glucosidases, on the other hand, were formed constitutively and were primarily cell free, but with a small amount strongly associated with the cell wall. Low 1,4-β-glucosidase activities of periplasmic or intracellular origin were also found. A rotational viscosimetric method was developed to measure the total endo-1,4-β-glucanase activity of the culture (broth and solids). By this method, it was possible to determine the endo-1,4-β-glucanase activity not only in the supernatant of the culture but also on the surface of the mycelium or absorbed on residual Avicel. During a 70-liter batch cultivation of P. janthinellum, the adsorption of endo-1,4-β-glucanases by residual and newly added 10% Avicel was measured. The adsorption of soluble protein and endo-1,4-β-glucanases by Avicel was found to be largely independent of the pH value but dependent on temperature.  相似文献   

5.
The retaining endo-1,3-β-d-glucanase (LV) with molecular mass of 36 kDa was purified to homogeneity from the crystalline styles of scallop Mizuhopecten yessoensis. The purified enzyme catalyzed hydrolysis of laminaran as endo-enzyme forming glucose, laminaribiose and higher oligosaccharides as products (Km  600 μg/mL). The 1,3-β-d-glucanase effectively catalyzed transglycosylation reaction that is typical of endo-enzymes too. Optima of pH and temperature were at 4.5 and 45 °C, respectively. cDNA encoding the endo-1,3-β-d-glucanase was cloned by PCR-based methods. It contained an open reading frame that encoded 339-amino acids protein. The predicted endo-1,3-β-d-glucanase amino acid sequence included a characteristic domain of the glycosyl hydrolases family 16 and revealed closest homology with 1,3-β-d-glucanases from bivalve Pseudocardium sachalinensis, sea urchin Strongylocentrotus purpuratus and invertebrates lipopolysaccharide and β-1,3-glucan-binding proteins.The fold of the LV was more closely related to κ-carrageenase, agarase and 1,3;1,4-β-d-glucanase from glycosyl hydrolases family 16. Homology model of the endo-1,3-β-d-glucanase from M. yessoensis was obtained with MOE on the base of the crystal structure of κ-carrageenase from P. carrageonovora as template. Putative three-dimensional structures of the LV complexes with substrate laminarihexaose or glucanase inhibitor halistanol sulfate showed that the binding sites of the halistanol sulfate and laminarihexaose are located in the enzyme catalytic site and overlapped.  相似文献   

6.
A xyloglucan-specific endo-1,4-[beta]-glucanase was isolated from the apoplast fraction of auxin-treated pea (Pisum sativum) stems, in which both the rate of stem elongation and the amount of xyloglucan solubilized were high. The enzyme was purified to apparent homogeneity by sequential cation-exchange chromatographies, affinity chromatography, and gel filtration. The purified enzyme gave a single protein band on sodium dodecyi sulfate-polyacrylamide gel electrophoresis, and the molecular size was determined to be 77 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 70 kD by gel filtration. The isoelectric point was about 8.1. The enzyme specifically cleaved the 1,4-[beta]-glucosyl linkages of the xyloglucan backbone to yield mainly nona- and heptasaccharides but did not hydrolyze carboxymethylcellulose, swollen cellulose, and (1->3, 1->4)-[beta]-glucan. By hydrolysis, the average molecular size of xyloglucan was decreased from 50 to 20 kD with new reducing chain ends in the lower molecular size fractions. This suggests that the enzyme has endo-1,4-[beta]-glucanase activity against xyloglucan. In conclusion, a xyloglucan-specific endo-1,4-[beta]-glucanase with an activity that differs from the activities of cellulase and xyloglucan endotransglycosylase has been isolated from elongating pea stems.  相似文献   

7.
In this study, a novel β-1,3-1,4-glucanase gene (designated as PtLic16A) from Paecilomyces thermophila was cloned and sequenced. PtLic16A has an open reading frame of 945 bp, encoding 314 amino acids. The deduced amino acid sequence shares the highest identity (61%) with the putative endo-1,3(4)-β-glucanase from Neosartorya fischeri NRRL 181. PtLic16A was cloned into a vector pPIC9K and was expressed successfully in Pichia pastoris as active extracellular β-1,3-1,4-glucanase. The recombinant β-1,3-1,4-glucanase (PtLic16A) was secreted predominantly into the medium which comprised up to 85% of the total extracellular proteins and reached a protein concentration of 9.1 g l−1 with an activity of 55,300 U ml−1 in 5-l fermentor culture. The enzyme was then purified using two steps, ion exchange chromatography, and gel filtration chromatography. The purified enzyme had a molecular mass of 38.5 kDa on SDS–PAGE. It was optimally active at pH 7.0 and a temperature of 70°C. Furthermore, the enzyme exhibited strict specificity for β-1,3-1,4-d-glucans. This is the first report on the cloning and expression of a β-1,3-1,4-glucanase gene from Paecilomyces sp.  相似文献   

8.
An enzyme preparation has been produced on the basis of Penicillium canescens strains with the activity of cellibiohydrolase I, II; endo-1,4-β-gluconase of Penicillium verruculosum; and β-glucosidase of Aspergillus niger. It was shown that for the most effective hydrolysis of aspen wood pulp the optimal ratio of cellobiohydrolase and endo-1,4-β-gluconase in enzyme preparations was 8: 2 (by protein). It was also established that the homologous xylanase secreted by the Penicillium canescens fungus is a required component for the enzyme complex for hydrolysis of the hemicellulose matrix of aspen wood.  相似文献   

9.
The ripening of raspberry fruit (Rubus ideausL. cv Glen Clova)is associated with a climacteric rise in ethylene production.As the fruit pigments change from green to red there is a progressivesoftening, loss of skin strength and a breakdown of cell wallsin the mesocarp. An increase in cellulase (endo-1,4-ß-D-glucanase)in both drupelets and receptacles accompanies these changes.The localization of cellulase in the regions of the fruit associatedwith abscission zones suggest the enzyme may be involved infruit separation as well as softening. Rubus idaeusL; raspberry; fruit ripening; ethylene; abscission; cell wall breakdown; cellulase; endo-1,4-ß-D-glucanase  相似文献   

10.
The formation and location of endo-1,4-β-glucanases and β-glucosidases were studied in cultures of Cellulomonas uda grown on microcrystalline cellulose, carboxymethyl cellulose, printed newspaper, and some mono- or disaccharides. Endo-1,4-Glucanases were found to be extracellular, but a very small amount of cell-bound endo-1,4-β-glucanase was considered to be the basal endoglucanase level of the cells. The formation of extracellular endo-1,4-β-glucanases was induced by cellobiose and repressed by glucose. Extracellular endoglucanase activity was inhibited by cellobiose but not by glucose. β-Glucosidases, on the other hand, were formed constitutively and found to be cell bound. β-Glucosidase activity was inhibited noncompetitively by glucose. Some characteristics such as the optimal pH for and the thermostability of the endoglucanases and β-glucosidases and the end products of cellulose degradation were determined.  相似文献   

11.
Xyloglucan 4-ß-D-glucosyltransferase, an enzyme responsiblefor the formation of the xyloglucan backbone, in a particulatepreparation of soybean cells has been compared with ß-1,4-glucan4-ß-D-glucosyltransferase of the same origin. Thefollowing observations indicate that the enzyme system of xyloglucansynthesis does not contain ß-1,4-glucan 4-ß-D-glucosyltransferaseactivity, although both enzymes transfer the glucosyl residuefrom UDP-glucose to form the ß-1,4-glucosidic linkage:1. The incorporation of [14C]glucose into xyloglucan dependedon the presence of UDP-xylose in the incubation mixture. 2.No measurable amount of radioactivity was incorporated fromUDP-[14C]xylose into the cello-oligosaccharides, although theincorporation of [14C]xylose into xyloglucan depended on thepresence of UDP-glucose in the incubation mixture (Hayashi andMatsuda 1981b). 3. The activity of xyloglucan 4-ß-D-glucosyltransferasewas stimulated more strongly by Mn2+ than by Mg2+, whereas Mg2+was the most active stimulator for the activity of ß-1,4-glucan4-ß-D-glucosyltransferase. 4. An addition of GDP-glucose(100 µM) to the incubation mixture inhibited the activityof xyloglucan 4-ß-D-glucosyltransferase by 17%, whereasthe activity of ß-1,4-glucan 4-ß-D-glucosyltransferasewas inhibited 56% under the same conditions. 5. Irpex exo-cellulasedid not hydrolyze the xyloglucan synthesized in vitro. 6. Theß-1,4-glucan synthesized in vitro was not a branchedxyloglucan because it gave no 2,3-di-O-methyl glucose derivativeon methylation analysis. 7. Pulse-chase experiments indicatedthat the ß-1,4-glucan was not transformed into thexyloglucan. The subcellular distribution of the xyloglucan synthase, however,was similar to that of the ß-1,4-glucan synthase (Golgi-located1,4-ß-D-glucan 4-ß-D-glucosyltransferase).Thus, it appears that the latter enzyme is located at a siteclose to xyloglucan synthase and is set aside for the assemblyof these polysaccharides into the plant cell surface. (Received May 21, 1981; Accepted October 13, 1981)  相似文献   

12.
A macromolecular complex composed of xyloglucan and cellulosewas isolated from elongating regions of stems of etiolated pea(Pisum sativum L. var Alaska) seedlings and binding of a xyloglucan-specificantibody was examined after treatment of the complex with endo-1,4-ß-glucanaseor 24% KOH. The antibody bound to the complex but the extentof binding was reduced after treatment of the complex with endo-1,4-ß-glucanaseand was hardly detectable after treatment with 24% KOH. Themolecular weight of the xyloglucan that remained (5%) in theß-glucanase-treated complexes was less than 9,200.Pea xyloglucan was allowed to bind to enzymeand alkali-treatedcomplexes to generaly reconstituted complexes. The amount ofthe antibody that bound to each type of reconstituted complexwas similar but was much lower than that bound to the nativecomplex. Immunogold labeling indicated that most of the antigenwas widely distributed between microfibrils in the native complex,whereas the antigen appeared to be confined to the microfibrilsin the reconstituted complexes. These findings suggest thata part of each xyloglucan molecule is strongly associated withcellulose microfibrils while the rest is free of the microfibrilsin the native complex. 1This work was supported in part by a grant from the YamadaScience Foundation.  相似文献   

13.
【目的】在毕赤酵母中表达特异腐质霉Humicola insolens的中性内切葡聚糖酶Ⅱ,并对其性质加以研究。【方法】利用RT-PCR的方法,以特异腐质霉(Humicola insolens)NC3总RNA为模板,克隆到中性内切葡聚糖酶Ⅱ基因(egⅡ)的cDNA。将其插入表达载体pPIC9K,重组质粒经线性化后电击转化毕赤酵母(Pichia pastoris)菌株GS115。【结果】SDS-PAGE和酶活的检测结果均表明:egⅡ基因在毕赤酵母中成功表达。重组酶的部分酶学性质研究表明,该酶的最适反应温度为70°C,且在65°C以下具有较好的热稳定性。最适反应pH为6.5,在pH 6.0?7.0之间有较好的稳定性。【结论】用重组毕赤酵母可高效表达外源中性内切葡聚糖酶,为其今后在工业应用奠定了基础。  相似文献   

14.
1,3-1,4-β-d-glucanase is an important endoglycosidase in the brewing and animal feed industries. To achieve high-level expression of recombinant glucanase in Pichia pastoris, we designed sequences encoding the α-factor signal peptide from Saccharomyces cerevisiae and the truncated 1,3-1,4-β-d-glucanase from Fibrobacter succinogenes as a whole. The codons encoding the 52 amino acids of the signal peptide and 106 residues of the glucanase protein were optimized for expression in P. pastoris; 189 nucleotides were changed. The G + C content was adjusted to 48–49%, and AT-rich stretches were eliminated to avoid premature termination. The messenger ribonucleic acid secondary structure near the AUG start codon was also adjusted to ensure efficient translation; the resulting glucanase production was twofold higher compared with that achieved with gene structure optimization alone. We also propose a new fermentation strategy for the induction phase, in which 5/95% glycerol/methanol mixed feed was used in days 1–3 and 100% methanol was used on days 4–6. By comparison with methanol feed and glycerol/methanol-mixed feed alone, the yield of recombinant glucanase increased by 38.5 and 16.5%, respectively. The expressed optimized recombinant 1,3-1,4-β-d-glucanase constituted ~90% of the total secreted protein, reaching up to 3 g l−1 in the medium.  相似文献   

15.
A ß-D-glucanase activity hydrolyzing 1,3:1,4-ß-D-glucanwas released from the cell walls of barley by 3M LiCl treatment.It was purified by sequential cation-exchange, gel-filtrationand hydrophobic chromatography. The molecular mass of the glucanasewas 66 kDa as determined by SDS-polyacrylamide gel electrophoresis.Sequence determination of the first thirty amino acids of theN-terminus revealed a high homology of this enzyme to the Pseudomonasl,4-ß-D-glucosidase (56.5%). The purified ß-D-glucanasehas a pH optimum at 5.0, and hydrolyzes oligosaccharides containingß-D-1,3 or ß-D-1,4 linkage. The glucanaseshowed maximum hydrolytic activity toward laminaritetraose,the rate being about two times that of cellotetraose and aboutfour times that of gentiobiose. Polysaccharides such as lichenan,l,3:l,4-ß-D-glucan (from barley), laminarin and pustulanare also hydrolyzed, but not carboxylmethyl-curdlan, carboxymethyl-cellulose,xyloglucan and maltose. The purified ß-D-glucanaseyielded monomeric glucose from laminarihexaose, and exhibitedcharacteristics of an exo-l,3-ß-D-glucanase (EC 3.2.1.58 [EC] ).The activity and biochemical characteristics of this enzymesuggest that it is an exo-l,3-ß-D-glucanase involvedin the rapid turnover of l,3:l,4-ß-D-glucan in barleycell walls during seedling growth. (Received September 24, 1996; Accepted December 9, 1996)  相似文献   

16.
Geshi N  Jørgensen B  Scheller HV  Ulvskov P 《Planta》2000,210(4):622-629
 The biosynthesis of galactan was investigated using microsomal membranes isolated from suspension-cultured cells of potato (Solanum tuberosum L. var. AZY). Incubation of the microsomal membranes in the presence of UDP-[14C]galactose resulted in a radioactive product insoluble in 70% methanol. The product released only [14C]galactose upon acid hydrolysis. Treatment of the product with Aspergillus niger endo-1,4-β-galactanase released 65–70% of the radioactivity to a 70%-methanol-soluble fraction. To a minor extent, [14C]galactose was also incorporated into proteins, however these galactoproteins were not a substrate for Aspergillus niger endo-1,4-β-galactanase. Thus, the majority of the 14C-labelled product was 1,4-β-galactan. Compounds released by the endo-1,4-β-galactanase treatment were mainly [14C]galactose and [14C]galactobiose, indicating that the synthesized 1,4-β-galactan was longer than a trimer. In vitro synthesis of 1,4-β-galactan was most active with 6-d-old cells, which are in the middle of the linear growth phase. The optimal synthesis occurred at pH 6.0 in the presence of 7.5 mM Mn2+. Aspergillus aculeatus rhamnogalacturonase A digested at least 50% of the labelled product to smaller fragments of approx. 14 kDa, suggesting that the synthesized [14C]galactan was attached to the endogenous rhamnogalacturonan I. When rhamnogalacturonase A digests of the labelled product were subsequently treated with endo-1,4-β-galactanase, radioactivity was not only found as [14C]galactose or [14C]galactobiose but also as larger fragments. The larger fragments were likely the [14C]galactose or [14C]galactobiose still attached to the rhamnogalacturonan backbone since treatment with β-galactosidase together with endo-1,4-β-galactanase digested all radioactivity to the fraction eluting as [14C]galactose. The data indicate that the majority of the [14C]galactan was attached directly to the rhamnose residues in rhamnogalacturonan I. Thus, isolated microsomal membranes contain enzyme activities to both initiate and elongate 1,4-β-galactan sidechains in the endogenous pectic rhamnogalacturonan I. Received: 24 June 1999 / Accepted: 30 August 1999  相似文献   

17.
The availability of sequenced insect genomes has allowed for discovery and functional characterization of novel genes and proteins. We report use of the Tribolium castaneum (Herbst) (red flour beetle) genome to identify, clone, express, and characterize a novel endo-β-1,4-glucanase we named TcEG1 (T. castaneum endoglucanase 1). Sequence analysis of a full-length TcEG1 cDNA clone (1356 bp) revealed sequence homology to enzymes in glycosyl hydrolase family 9 (GHF9), and verified presence of a change (Gly for Ser) in the conserved catalytic domain for GHF9 cellulases. This TcEG1 cDNA clone was predicted to encode a 49.5 kDa protein with a calculated pI of 5.39. Heterologous expression of TcEG1 in Drosophila S2 cell cultures resulted in secretion of a 51-kDa protein, as determined by Western blotting. The expressed protein was used to characterize TcEG1 enzymatic activity against two cellulose substrates to determine its specificity and stability. Our data support that TcEG1 as a novel endo-β-1,4-glucanase, the first functional characterization of a cellulase enzyme derived from an insect genome with potential applications in the biofuel industry due to its high relative activity at alkaline pH.  相似文献   

18.
The cause of differences in germination rates in a cold-toleranttomato line (PI341988), a control line (UC82B), and six progenylines stemming from crosses and backcrosses between the twoparent lines was investigated. Pursuant to earlier work showingthat differences in germination ability at 12°C are dueto the barrier imposed by the endosperm layer, we analysed theactivity of cell-wall-hydrolysing enzymes extracted from theselines. A significant increase in endomannanase activity wasfound in plant line PI341988 prior to germination at 12°C.Extracts of PI341988 seeds that had imbibed at either 12 or25°C exhibited higher endomannanase activity than theircounterparts from plant line UC82B. Moreover, a positive relationshipwas found between germination ability at low temperature andendomannanase activity in the six progeny lines. Analysis ofendomannanase activity in sub-regions of the seed indicatedthat the increase in activity prior to germination was higherin the micropylar endosperm cap than in the rest of the seed.Exogenous application of mannanase originating from soil-bornebacteria increased germination rates under both moderate andlow temperature conditions. Cellulase (endo-1,4-ß-glucanase)activity was also found to be higher in plant line PI341988.However, the activity of this enzyme probably increases aftergermination and it is therefore not considered as a key enzymecontrolling germination at low temperatures.Copyright 1995,1999 Academic Press Lycopersicon esculentum, tomato, seed germination, cell wall  相似文献   

19.
Two auxin-induced endo-1,4-β-glucanases (EC 3.2.1.4) were purified from pea (Pisum sativum L. var. Alaska) epicotyls and used to degrade purified pea xyloglucan. Hydrolysis yielded nonasaccharide (glucose/xylose/galactose/fucose, 4:3:1:1) and heptasaccharide (glucose/xylose, 4:3) as the products. The progress of hydrolysis, as monitored viscometrically (with amyloid xyloglucan) and by determination of residual xyloglucan-iodine complex (pea) confirmed that both pea glucanases acted as endohydrolases versus xyloglucan. Km values for amyloid and pea xyloglucans were approximately the same as those for cellulose derivatives, but Vmax values were lower for the xyloglucans. Auxin treatment of epicotyls in vivo resulted in increases in net deposits of xyloglucan and cellulose in spite of a great increase (induction) of endogenous 1,4-β-glucanase activity. However, the average degree of polymerization of the resulting xyloglucan was much lower than in controls, and the amount of soluble xyloglucan increased. When macromolecular complexes of xyloglucan and cellulose (cell wall ghosts) were treated in vitro with pea 1,4-β-glucanase, the xyloglucan component was preferentially hydrolyzed and solubilized. It is concluded that xyloglucan is the main cell wall substrate for pea endo-1,4-β-glucanase in growing tissue.  相似文献   

20.
β-Glucosidases designated MoCel3A and MoCel3B were successfully overexpressed in Magnaporthe oryzae. MoCel3A and MoCel3B showed optimal activity at 50 °C and pH 5.0–5.5. MoCel3A exhibited higher activity on higher degree of polymerization (DP) oligosaccharides and on β-1,3-linked oligosaccharides than on β-1,4-linked oligosaccharides. Furthermore, MoCel3A could liberate glucose from polysaccharides such as laminarin, 1,3-1,4-β-glucan, phosphoric acid-swollen cellulose, and pustulan, of which laminarin was the most suitable substrate. Conversely, MoCel3B preferentially hydrolyzed lower DP oligosaccharides such as cellobiose, cellotriose, and laminaribiose. Furthermore, the synergistic effects of combining enzymes including MoCel3A and MoCel3B were investigated. Depolymerization of 1,3-1,4-β-glucan by M. oryzae cellobiohydrolase (MoCel6A) enhanced the production of glucose by the actions of MoCel3A and MoCel3B. In these reactions, MoCel3A hydrolyzed higher DP oligosaccharides, resulting in the release of glucose and cellobiose, and MoCel3B preferentially hydrolyzed lower DP oligosaccharides including cellobiose. On the other hand, MoCel3A alone produced glucose from laminarin at levels equivalent to 80% of maximal hydrolysis obtained by the combined action of MoCel3A, MoCel3B, and endo-1,3-β-glucanase. Therefore, MoCel3A and MoCel3B activities yield glucose from not only cellulosic materials but also hemicellulosic polysaccharides.  相似文献   

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