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Zhang J, Moilanen U, Tang M, Viikari L. The carbohydrate-binding module of xylanase from Nonomuraea flexuosa decreases its non-productive adsorption on lignin. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:18. [PMID: 23363927 PMCID: PMC3577619 DOI: 10.1186/1754-6834-6-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 01/21/2013] [Indexed: 05/08/2023]
Abstract
BACKGROUND The enzymatic hydrolysis step converting lignocellulosic materials into fermentable sugars is recognized as one of the major limiting steps in biomass-to-ethanol process due to the low efficiency of enzymes and their cost. Xylanases have been found to be important in the improvement of the hydrolysis of cellulose due to the close interaction of cellulose and xylan. In this work, the effects of carbohydrate-binding module (CBM family II) of the xylanase 11 from Nonomuraea flexuosa (Nf Xyn11) on the adsorption and hydrolytic efficiency toward isolated xylan and lignocellulosic materials were investigated. RESULTS The intact family 11 xylanase of N. flexuosa clearly adsorbed on wheat straw and lignin, following the Langmuir-type isotherm. The presence of the CBM in the xylanase increased the adsorption and hydrolytic efficiency on insoluble oat spelt xylan. But the presence of the CBM did not increase adsorption on pretreated wheat straw or isolated lignin. On the contrary, the CBM decreased the adsorption of the core protein to lignin containing substrates, indicating that the CBM of N. flexuosa xylanase did not contribute to the non-productive adsorption. CONCLUSION The CBM of the N. flexuosa xylanase was shown to be a xylan-binding module, which had low affinity on cellulose. The CBM of the N. flexuosa xylanase reduced the non-specific adsorption of the core protein to lignin and showed potential for improving the hydrolysis of lignocellulosic materials to platform sugars.
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Affiliation(s)
- Junhua Zhang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100, China
| | - Ulla Moilanen
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki, Finland
| | - Ming Tang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100, China
| | - Liisa Viikari
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki, Finland
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52
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Chong SL, Koutaniemi S, Virkki L, Pynnönen H, Tuomainen P, Tenkanen M. Quantitation of 4-O-methylglucuronic acid from plant cell walls. Carbohydr Polym 2013; 91:626-30. [DOI: 10.1016/j.carbpol.2012.08.078] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/03/2012] [Accepted: 08/23/2012] [Indexed: 12/01/2022]
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53
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Tenkanen M, Vršanská M, Siika-aho M, Wong DW, Puchart V, Penttilä M, Saloheimo M, Biely P. Xylanase XYN IV from Trichoderma reesei showing exo- and endo-xylanase activity. FEBS J 2012; 280:285-301. [PMID: 23167779 DOI: 10.1111/febs.12069] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/07/2012] [Accepted: 11/15/2012] [Indexed: 11/29/2022]
Abstract
A minor xylanase, named XYN IV, was purified from the cellulolytic system of the fungus Trichoderma reesei Rut C30. The enzyme was discovered on the basis of its ability to attack aldotetraohexenuronic acid (HexA-2Xyl-4Xyl-4Xyl, HexA(3)Xyl(3)), releasing the reducing-end xylose residue. XYN IV exhibited catalytic properties incompatible with previously described endo-β-1,4-xylanases of this fungus, XYN I, XYN II and XYN III, and the xylan-hydrolyzing endo-β-1,4-glucanase EG I. XYN IV was able to degrade several different β-1,4-xylans, but was inactive on β-1,4-mannans and β-1,4-glucans. It showed both exo-and endo-xylanase activity. Rhodymenan, a linear soluble β-1,3-β-1,4-xylan, was as the best substrate. Linear xylooligosaccharides were attacked exclusively at the first glycosidic linkage from the reducing end. The gene xyn4, encoding XYN IV, was also isolated. It showed clear homology with xylanases classified in glycoside hydrolase family 30, which also includes glucanases and mannanases. The xyn4 gene was expressed slightly when grown on xylose and xylitol, clearly on arabinose, arabitol, sophorose, xylobiose, xylan and cellulose, but not on glucose or sorbitol, resembling induction of other xylanolytic enzymes from T. reesei. A recombinant enzyme prepared in a Pichia pastoris expression system exhibited identical catalytic properties to the enzyme isolated from the T. reesei culture medium. The physiological role of this unique enzyme remains unknown, but it may involve liberation of xylose from the reducing end of branched oligosaccharides that are resistant toward β-xylosidase and other types of endoxylanases. In terms of its catalytic properties, XYN IV differs from bacterial GH family 30 glucuronoxylanases that recognize 4-O-methyl-D-glucuronic acid (MeGlcA) substituents as substrate specificity determinants.
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Affiliation(s)
- Maija Tenkanen
- VTT Technical Research Centre of Finland, Espoo, Finland
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54
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Kallioinen A, Uusitalo J, Pahkala K, Kontturi M, Viikari L, Weymarn NV, Siika-Aho M. Reed canary grass as a feedstock for 2nd generation bioethanol production. BIORESOURCE TECHNOLOGY 2012; 123:669-672. [PMID: 22939601 DOI: 10.1016/j.biortech.2012.07.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/03/2012] [Accepted: 07/05/2012] [Indexed: 06/01/2023]
Abstract
The enzymatic hydrolysis and fermentation of reed canary grass, harvested in the spring or autumn, and barley straw were studied. Steam pretreated materials were efficiently hydrolysed by commercial enzymes with a dosage of 10-20FPU/g d.m. Reed canary grass harvested in the spring was hydrolysed more efficiently than the autumn-harvested reed canary grass. Additional β-glucosidase improved the release of glucose and xylose during the hydrolysis reaction. The hydrolysis rate and level of reed canary grass with a commercial Trichoderma reesei cellulase could be improved by supplementation of purified enzymes. The addition of CBH II improved the hydrolysis level by 10% in 48hours' hydrolysis. Efficient mixing was shown to be important for hydrolysis already at 10% dry matter consistency. The highest ethanol concentration (20g/l) and yield (82%) was obtained with reed canary grass at 10% d.m. consistency.
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Affiliation(s)
- Anne Kallioinen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Finland.
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55
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Abstract
α-Glucuronidase enzymes play an essential role in the full enzymatic hydrolysis of hemicellulose. Up to this point, all genes encoding α-glucuronidase enzymes have been cloned from individual, pure culture strains. Using a high-throughput screening strategy, we have isolated the first α-glucuronidase gene (rum630-AG) from a mixed population of microorganisms. The gene was subcloned into a prokaryotic vector, and the enzyme was overexpressed and biochemically characterized. The RUM630-AG enzyme had optimum activity at pH 6.5 and 40 °C. When birchwood xylan was used as substrate, the RUM630-AG functioned synergistically with an endoxylanase enzyme to hydrolyze the substrate.
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56
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Niemi P, Tamminen T, Smeds A, Viljanen K, Ohra-aho T, Holopainen-Mantila U, Faulds CB, Poutanen K, Buchert J. Characterization of lipids and lignans in brewer's spent grain and its enzymatically extracted fraction. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:9910-9917. [PMID: 22963516 DOI: 10.1021/jf302684x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Brewer's spent grain (BSG), the major side stream of brewing, consists of the husks and the residual parts of malts after the mashing process. BSG was enzymatically fractionated by a two-step treatment with carbohydrate- and protein-degrading enzymes, which solubilized 66% of BSG. BSG contained 11% lipids, which were mostly triglycerides, but also a notable amount of free fatty acids was present. Lipids were mostly solubilized due to the alkaline pH applied in the protease treatment. The main fatty acids were linoleic, palmitic, and oleic acids. Several lignans were identified in BSG, syringaresinol and secoisolariciresinol being the most abundant, many associated with the cell wall matrix and released by the alkaline-protease treatment.
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Affiliation(s)
- Piritta Niemi
- Bio and Process Technology, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
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57
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Koutaniemi S, Guillon F, Tranquet O, Bouchet B, Tuomainen P, Virkki L, Petersen HL, Willats WGT, Saulnier L, Tenkanen M. Substituent-specific antibody against glucuronoxylan reveals close association of glucuronic acid and acetyl substituents and distinct labeling patterns in tree species. PLANTA 2012; 236:739-51. [PMID: 22526506 DOI: 10.1007/s00425-012-1653-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 04/11/2012] [Indexed: 05/18/2023]
Abstract
Immunolabeling can be used to locate plant cell wall carbohydrates or other components to specific cell types or to specific regions of the wall. Some antibodies against xylans exist; however, many partly react with the xylan backbone and thus provide limited information on the type of substituents present in various xylans. We have produced a monoclonal antibody which specifically recognizes glucopyranosyl uronic acid (GlcA), or its 4-O-methyl ether (meGlcA), substituents in xylan and has no cross-reactivity with linear or arabinofuranosyl-substituted xylans. The UX1 antibody binds most strongly to (me)GlcA substitutions at the non-reducing ends of xylan chains, but has a low cross-reactivity with internal substitutions as well, at least on oligosaccharides. The antibody labeled plant cell walls from both mono- and dicotyledons, but in most tissues an alkaline pretreatment was needed for antibody binding. The treatment removed acetyl groups from xylan, indicating that the vicinity of glucuronic acid substituents is also acetylated. The novel labeling patterns observed in the xylem of tree species suggested that differences within the cell wall exist both in acetylation degree and in glucuronic acid content.
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Affiliation(s)
- Sanna Koutaniemi
- Department of Food and Environmental Sciences, University of Helsinki, PO Box 27, 00014, Helsinki, Finland.
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58
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Kemppainen K, Inkinen J, Uusitalo J, Nakari-Setälä T, Siika-aho M. Hot water extraction and steam explosion as pretreatments for ethanol production from spruce bark. BIORESOURCE TECHNOLOGY 2012; 117:131-139. [PMID: 22613888 DOI: 10.1016/j.biortech.2012.04.080] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/18/2012] [Accepted: 04/21/2012] [Indexed: 05/27/2023]
Abstract
Spruce bark is a source of interesting polyphenolic compounds and also a potential but little studied feedstock for sugar route biorefinery processes. Enzymatic hydrolysis and fermentation of spruce bark sugars to ethanol were studied after three different pretreatments: steam explosion (SE), hot water extraction (HWE) at 80 °C, and sequential hot water extraction and steam explosion (HWE+SE), and the recovery of different components was determined during the pretreatments. The best steam explosion conditions were 5 min at 190 °C without acid catalyst based on the efficiency of enzymatic hydrolysis of the material. However, when pectinase was included in the enzyme mixture, the hydrolysis rate and yield of HWE bark was as good as that of SE and HWE+SE barks. Ethanol was produced efficiently with the yeast Saccharomyces cerevisiae from the pretreated and hydrolysed materials suggesting the suitability of spruce bark to various lignocellulosic ethanol process concepts.
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59
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Niemi P, Faulds CB, Sibakov J, Holopainen U, Poutanen K, Buchert J. Effect of a milling pre-treatment on the enzymatic hydrolysis of carbohydrates in brewer's spent grain. BIORESOURCE TECHNOLOGY 2012; 116:155-160. [PMID: 22609670 DOI: 10.1016/j.biortech.2012.04.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 04/11/2012] [Accepted: 04/13/2012] [Indexed: 06/01/2023]
Abstract
Millions of tonnes of brewer's spent grain (BSG) are annually produced worldwide as a by-product of the brewing industry. BSG has the potential to be a valuable source of food, chemicals and energy if cost-efficient fractionation methods can be developed. A 2-fold improvement in carbohydrate solubilisation could be achieved through the introduction of a milling step prior to enzymatic hydrolysis. Course and fine milled fractions were characterized by particle size distribution and light microscopy. Fine milling decreased particle size down to the micron level and this in turn improved the carbohydrate solubility yield by a multi-enzyme mixture from 23% up to 45%. Carbohydrate solubilisation could be further increased through the supplementation of this enzyme preparation with additional cellulases. The physical degradation caused by the milling also liberated soluble carbohydrates without the requirement of any enzymatic treatment.
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Affiliation(s)
- Piritta Niemi
- VTT Technical Research Centre of Finland, Espoo FI-02044 VTT, Finland.
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60
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Heinze T, Daus S. Xylan and Xylan Derivatives – Basis of Functional Polymers for the Future. RENEWABLE RESOURCES FOR FUNCTIONAL POLYMERS AND BIOMATERIALS 2011. [DOI: 10.1039/9781849733519-00088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This review highlights xylan and xylan derivatives. It depicts the occurrence and structural diversity of the biopolymer, followed by a presentation of different ways of isolation from biomass. The determination of characteristics, i.e., molecular weight, interaction with other polysaccharides, thermal behaviour, and the biological activity of xylan are reviewed. The application potential arising from the structural features of the unmodified xylan is pointed out. Special attention is concentrated on the possibilities of the modification of functional properties by chemical functionalization of the biopolymers in order to design advanced materials. Within this review recent results in the field are accompanied with selected results of our own work.
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Affiliation(s)
- Thomas Heinze
- Centre of Excellence for Polysaccharide Research Friedrich Schiller University of Jena, Humboldtstraße 10 D-07743 Jena Germany
| | - Stephan Daus
- Centre of Excellence for Polysaccharide Research Friedrich Schiller University of Jena, Humboldtstraße 10 D-07743 Jena Germany
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61
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Pouvreau L, Jonathan M, Kabel M, Hinz S, Gruppen H, Schols H. Characterization and mode of action of two acetyl xylan esterases from Chrysosporium lucknowense C1 active towards acetylated xylans. Enzyme Microb Technol 2011; 49:312-20. [DOI: 10.1016/j.enzmictec.2011.05.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 05/10/2011] [Accepted: 05/16/2011] [Indexed: 11/24/2022]
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62
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Fungal enzyme sets for plant polysaccharide degradation. Appl Microbiol Biotechnol 2011; 91:1477-92. [PMID: 21785931 PMCID: PMC3160556 DOI: 10.1007/s00253-011-3473-2] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/27/2011] [Accepted: 07/10/2011] [Indexed: 02/01/2023]
Abstract
Enzymatic degradation of plant polysaccharides has many industrial applications, such as within the paper, food, and feed industry and for sustainable production of fuels and chemicals. Cellulose, hemicelluloses, and pectins are the main components of plant cell wall polysaccharides. These polysaccharides are often tightly packed, contain many different sugar residues, and are branched with a diversity of structures. To enable efficient degradation of these polysaccharides, fungi produce an extensive set of carbohydrate-active enzymes. The variety of the enzyme set differs between fungi and often corresponds to the requirements of its habitat. Carbohydrate-active enzymes can be organized in different families based on the amino acid sequence of the structurally related catalytic modules. Fungal enzymes involved in plant polysaccharide degradation are assigned to at least 35 glycoside hydrolase families, three carbohydrate esterase families and six polysaccharide lyase families. This mini-review will discuss the enzymes needed for complete degradation of plant polysaccharides and will give an overview of the latest developments concerning fungal carbohydrate-active enzymes and their corresponding families.
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63
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Rahikainen J, Mikander S, Marjamaa K, Tamminen T, Lappas A, Viikari L, Kruus K. Inhibition of enzymatic hydrolysis by residual lignins from softwood-study of enzyme binding and inactivation on lignin-rich surface. Biotechnol Bioeng 2011; 108:2823-34. [PMID: 21702025 DOI: 10.1002/bit.23242] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/27/2011] [Accepted: 06/13/2011] [Indexed: 11/11/2022]
Affiliation(s)
- Jenni Rahikainen
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Finland
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64
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Van Gool MP, Vancsó I, Schols HA, Toth K, Szakacs G, Gruppen H. Screening for distinct xylan degrading enzymes in complex shake flask fermentation supernatants. BIORESOURCE TECHNOLOGY 2011; 102:6039-47. [PMID: 21440435 DOI: 10.1016/j.biortech.2011.02.105] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 02/15/2011] [Accepted: 02/27/2011] [Indexed: 05/02/2023]
Abstract
The efficient degradation of complex xylans needs collaboration of many xylan degrading enzymes. Assays for xylan degrading activities based on reducing sugars or PNP substrates are not indicative for the presence of enzymes able to degrade complex xylans: They do not provide insight into the possible presence of xylanase-accessory enzymes within enzyme mixtures. A new screening method is described, by which specific xylan modifying enzymes can be detected. Fermentation supernatants of 78 different fungal soil isolates grown on wheat straw were analyzed by HPLC and MS. This strategy is powerful in recognizing xylanases, arabinoxylan hydrolases, acetyl xylan esterases and glucuronidases. No fungus produced all enzymes necessary to totally degrade the substrates tested. Some fungi produce high levels of xylanase active against linear xylan, but are unable to degrade complex xylans. Other fungi producing relative low levels of xylanase secrete many useful accessory enzyme component(s).
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Affiliation(s)
- M P Van Gool
- Wageningen University, Laboratory of Food Chemistry, Bomenweg 2, 6703 HD Wageningen, The Netherlands
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65
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Pouvreau L, Joosten R, Hinz SW, Gruppen H, Schols HA. Chrysosporium lucknowense C1 arabinofuranosidases are selective in releasing arabinose from either single or double substituted xylose residues in arabinoxylans. Enzyme Microb Technol 2011; 48:397-403. [DOI: 10.1016/j.enzmictec.2011.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 11/26/2010] [Accepted: 01/30/2011] [Indexed: 10/18/2022]
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66
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Chong SL, Battaglia E, Coutinho PM, Henrissat B, Tenkanen M, de Vries RP. The α-glucuronidase Agu1 from Schizophyllum commune is a member of a novel glycoside hydrolase family (GH115). Appl Microbiol Biotechnol 2011; 90:1323-32. [DOI: 10.1007/s00253-011-3157-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 10/18/2022]
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67
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Szijártó N, Horan E, Zhang J, Puranen T, Siika-aho M, Viikari L. Thermostable endoglucanases in the liquefaction of hydrothermally pretreated wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:2. [PMID: 21269447 PMCID: PMC3037870 DOI: 10.1186/1754-6834-4-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 01/26/2011] [Indexed: 05/03/2023]
Abstract
BACKGROUND Thermostable enzymes have several benefits in lignocellulose processing. In particular, they potentially allow the use of increased substrate concentrations (because the substrate viscosity decreases as the temperature increases), resulting in improved product yields and reduced capital and processing costs. A short pre-hydrolysis step at an elevated temperature using thermostable enzymes aimed at rapid liquefaction of the feedstock is seen as an attractive way to overcome the technical problems (such as poor mixing and mass transfer properties) connected with high initial solid loadings in the lignocellulose to ethanol process. RESULTS The capability of novel thermostable enzymes to reduce the viscosity of high-solid biomass suspensions using a real-time viscometric measurement method was investigated. Heterologously expressed enzymes from various thermophilic organisms were compared for their ability to liquefy the lignocellulosic substrate, hydrothermally pretreated wheat straw. Once the best enzymes were identified, the optimal temperatures for these enzymes to decrease substrate viscosity were compared. The combined hydrolytic properties of the thermostable preparations were tested in hydrolysis experiments. The studied mixtures were primarily designed to have good liquefaction potential, and therefore contained an enhanced proportion of the key liquefying enzyme, EGII/Cel5A. CONCLUSIONS Endoglucanases were shown to have a superior ability to rapidly reduce the viscosity of the 15% (w/w; dry matter) hydrothermally pretreated wheat straw. Based on temperature profiling studies, Thermoascus aurantiacus EGII/Cel5A was the most promising enzyme for biomass liquefaction. Even though they were not optimized for saccharification, many of the thermostable enzyme mixtures had superior hydrolytic properties compared with the commercial reference enzymes at 55°C.
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Affiliation(s)
- Nóra Szijártó
- University of Helsinki, Department of Food and Environmental Sciences, P.O. Box 27, FIN-00014, Helsinki, Finland
| | - Emma Horan
- University of Helsinki, Department of Food and Environmental Sciences, P.O. Box 27, FIN-00014, Helsinki, Finland
| | - Junhua Zhang
- University of Helsinki, Department of Food and Environmental Sciences, P.O. Box 27, FIN-00014, Helsinki, Finland
| | - Terhi Puranen
- Roal Oy, Tykkimäentie 15, FIN-05200, Rajamäki, Finland
| | - Matti Siika-aho
- VTT Technical Research Centre of Finland, PO Box 1000, FIN-02044, Espoo, Finland
| | - Liisa Viikari
- University of Helsinki, Department of Food and Environmental Sciences, P.O. Box 27, FIN-00014, Helsinki, Finland
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68
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Szijártó N, Siika-aho M, Sontag-Strohm T, Viikari L. Liquefaction of hydrothermally pretreated wheat straw at high-solids content by purified Trichoderma enzymes. BIORESOURCE TECHNOLOGY 2011; 102:1968-74. [PMID: 20884202 DOI: 10.1016/j.biortech.2010.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 09/03/2010] [Accepted: 09/03/2010] [Indexed: 05/03/2023]
Abstract
Enzymatic liquefaction was studied by measuring continuously the flowability change of high-solids lignocellulose substrates using a real time viscometric method. Hydrolysis experiments of hydrothermally pretreated wheat straw were carried out with purified enzymes from Trichoderma reesei; Cel7A, Cel6A, Cel7B, Cel5A, Cel12A and Xyn11A. Results obtained at 15% (w/w) solids revealed that endoglucanases, in particular Cel5A, are the key enzymes to rapidly reduce the viscosity of lignocellulose substrate. Cellobiohydrolases had only minor and the xylanase practically no effect on the viscosity. Efficient, fast liquefaction was obtained already at a dosage of 1.5 mg of Cel5A/gdrysolids. Partial replacement or supplementation of Cel5A by the other major hydrolytic enzymes did not improve the liquefaction. The reduction of viscosity did not correlate with the saccharification obtained in the same reaction, suggesting that efficient liquefaction is rather dependent on the site than the frequency of enzymatic cleavages.
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Affiliation(s)
- Nóra Szijártó
- University of Helsinki, Department of Food and Environmental Sciences, P.O. Box 27, FIN-00014 Helsinki, Finland.
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69
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Várnai A, Viikari L, Marjamaa K, Siika-aho M. Adsorption of monocomponent enzymes in enzyme mixture analyzed quantitatively during hydrolysis of lignocellulose substrates. BIORESOURCE TECHNOLOGY 2011; 102:1220-7. [PMID: 20736135 DOI: 10.1016/j.biortech.2010.07.120] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/28/2010] [Accepted: 07/29/2010] [Indexed: 05/03/2023]
Abstract
The adsorption of purified Trichoderma reesei cellulases (TrCel7A, TrCel6A and TrCel5A) and xylanase TrXyn11 and Aspergillus niger β-glucosidase AnCel3A was studied in enzyme mixture during hydrolysis of two pretreated lignocellulosic materials, steam pretreated and catalytically delignified spruce, along with microcrystalline cellulose (Avicel). The enzyme mixture was compiled to resemble the composition of commercial cellulase preparations. The hydrolysis was carried out at 35 °C to mimic the temperature of the simultaneous saccharification and fermentation (SSF). Enzyme adsorption was followed by analyzing the activity and the protein amount of the individual free enzymes in the hydrolysis supernatant. Most enzymes adsorbed quickly at early stages of the hydrolysis and remained bound throughout the hydrolysis, although the conversion reached was fairly high. Only with the catalytically oxidized spruce samples, the bound enzymes started to be released as the hydrolysis degree reached 80%. The results based on enzyme activities and protein assay were in good accordance.
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Affiliation(s)
- Anikó Várnai
- University of Helsinki, Food and Environmental Sciences, P.O. Box 27, 00014 Helsinki, Finland.
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70
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Fujimoto Z, Ichinose H, Biely P, Kaneko S. Crystallization and preliminary crystallographic analysis of the glycoside hydrolase family 115 α-glucuronidase from Streptomyces pristinaespiralis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 67:68-71. [PMID: 21206027 DOI: 10.1107/s1744309110043721] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 10/26/2010] [Indexed: 11/10/2022]
Abstract
α-Glucuronidase from Streptomyces pristinaespiralis (SpGlcA115A) is composed of a single-chain peptide containing a catalytic domain belonging to glycosyl hydrolase family 115, a novel family of hemicellulolytic α-glucuronidases. The enzyme catalyzes the hydrolysis of α-linked 4-O-methylglucuronosyl and glucuronosyl residues from both polymeric xylans and oligosaccharides. SpGlcA115A was crystallized at 293 K using the sitting-drop vapour-diffusion method. The crystals belonged to space group R3 and diffracted to a resolution of 1.9 Å.
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Affiliation(s)
- Zui Fujimoto
- Protein Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
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71
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Inverting character of family GH115 α-glucuronidases. FEBS Lett 2010; 584:4063-8. [DOI: 10.1016/j.febslet.2010.08.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 07/21/2010] [Accepted: 08/19/2010] [Indexed: 11/21/2022]
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72
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Várnai A, Siika-aho M, Viikari L. Restriction of the enzymatic hydrolysis of steam-pretreated spruce by lignin and hemicellulose. Enzyme Microb Technol 2010. [DOI: 10.1016/j.enzmictec.2009.12.013] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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73
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A novel family of hemicellulolytic alpha-glucuronidase. FEBS Lett 2009; 583:1457-62. [PMID: 19344716 DOI: 10.1016/j.febslet.2009.03.057] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 03/11/2009] [Accepted: 03/25/2009] [Indexed: 11/22/2022]
Abstract
Investigation of the xylanolytic enzyme system of the xylose-fermenting yeast Pichia stipitis resulted in the discovery of an extracellular alpha-glucuronidase efficiently debranching hardwood glucuronoxylan. This activity is not exhibited by more extensively investigated alpha-glucuronidases of glycoside hydrolase (GH) family 67, operating on substrates in which the uronic acid is linked to the non-reducing xylopyranosyl residues of main chain fragments. The N-terminus of the purified enzyme corresponded exactly to the P. stipitis gene ABN67901 coding for a protein of unknown function. BLAST search revealed the presence of similar genes in genomes of other microorganisms. These results lead to the emergence of a new family of alpha-glucuronidases.
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74
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Lee CC, Wagschal K, Kibblewhite-Accinelli RE, Orts WJ, Robertson GH, Wong DWS. An α-Glucuronidase Enzyme Activity Assay Adaptable for Solid Phase Screening. Appl Biochem Biotechnol 2008; 155:314-20. [DOI: 10.1007/s12010-008-8408-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 10/22/2008] [Indexed: 11/28/2022]
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75
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Simultaneous production of endo-β-1,4-xylanase and branched xylooligosaccharides by Thermomyces lanuginosus. J Biotechnol 2008; 137:34-43. [DOI: 10.1016/j.jbiotec.2008.07.1789] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 06/25/2008] [Accepted: 07/07/2008] [Indexed: 11/20/2022]
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76
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Cloning, characterisation and expression analysis of α-glucuronidase from the thermophilic fungus Talaromyces emersonii. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2007.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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77
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Hilditch S, Berghäll S, Kalkkinen N, Penttilä M, Richard P. The Missing Link in the Fungal D-Galacturonate Pathway. J Biol Chem 2007; 282:26195-201. [PMID: 17609199 DOI: 10.1074/jbc.m704401200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The fungal path for the catabolism of D-galacturonate is only partially known. It is however distinctly different to the well-known bacterial path. The known elements of the fungal path are D-galacturonate reductase converting D-galacturonate to L-galactonate and L-galactonate dehydratase converting L-galactonate to L-threo-3-deoxy-hexulosonate (2-keto-3-deoxy-L-galactonate). Here we describe the missing link in this pathway, an aldolase converting L-threo-3-deoxy-hexulosonate to pyruvate and L-glyceraldehyde. Fungal enzymes converting L-glyceraldehyde to glycerol have been described previously. The L-threo-3-deoxy-hexulosonate aldolase activity was induced in the mold Hypocrea jecorina (Trichoderma reesei) during growth on D-galacturonate. The enzyme was purified from this mold and a partial amino acid sequence obtained. This sequence was then used to identify the corresponding gene from the H. jecorina genome. The deletion of the gene resulted in a strain unable to grow on d-galacturonate and accumulating L-threo-3-deoxy-hexulosonate. The open reading frame was cloned from cDNA and functionally expressed in the yeast Saccharomyces cerevisiae. A histidine-tagged protein was expressed, purified, and characterized. The enzyme catalyzed reaction was reversible. With L-threo-3-deoxy-hexulosonate as substrate the K(m) was 3.5 mM and with pyruvate and L-glyceraldehyde the K(m) were 0.5 and 1.2 mM, respectively.
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Affiliation(s)
- Satu Hilditch
- VTT Technical Research Centre of Finland, Tietotie 2, Espoo, 02044 VTT, Finland
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78
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Viikari L, Alapuranen M, Puranen T, Vehmaanperä J, Siika-Aho M. Thermostable enzymes in lignocellulose hydrolysis. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:121-45. [PMID: 17589813 DOI: 10.1007/10_2007_065] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Thermostable enzymes offer potential benefits in the hydrolysis of lignocellulosic substrates; higher specific activity decreasing the amount of enzymes, enhanced stability allowing improved hydrolysis performance and increased flexibility with respect to process configurations, all leading to improvement of the overall economy of the process. New thermostable cellulase mixtures were composed of cloned fungal enzymes for hydrolysis experiments. Three thermostable cellulases, identified as the most promising enzymes in their categories (cellobiohydrolase, endoglucanase and beta-glucosidase), were cloned and produced in Trichoderma reesei and mixed to compose a novel mixture of thermostable cellulases. Thermostable xylanase was added to enzyme preparations used on substrates containing residual hemicellulose. The new optimised thermostable enzyme mixtures were evaluated in high temperature hydrolysis experiments on technical steam pretreated raw materials: spruce and corn stover. The hydrolysis temperature could be increased by about 10-15 degrees C, as compared with present commercial Trichoderma enzymes. The same degree of hydrolysis, about 90% of theoretical, measured as individual sugars, could be obtained with the thermostable enzymes at 60 degrees C as with the commercial enzymes at 45 degrees C. Clearly more efficient hydrolysis per assayed FPU unit or per amount of cellobiohydrolase I protein used was obtained. The maximum FPU activity of the novel enzyme mixture was about 25% higher at the optimum temperature at 65 degrees C, as compared with the highest activity of the commercial reference enzyme at 60 degrees C. The results provide a promising basis to produce and formulate improved enzyme products. These products can have high temperature stability in process conditions in the range of 55-60 degrees C (with present industrial products at 45-50 degrees C) and clearly improved specific activity, essentially decreasing the protein dosage required for an efficient hydrolysis of lignocellulosic substrates. New types of process configurations based on thermostable enzymes are discussed.
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Affiliation(s)
- Liisa Viikari
- University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland.
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79
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de Wet B, van Zyl W, Prior B. Characterization of the Aureobasidium pullulans α-glucuronidase expressed in Saccharomyces cerevisiae. Enzyme Microb Technol 2006. [DOI: 10.1016/j.enzmictec.2005.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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80
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Mierzwa M, Tokarzewska-Zadora J, Deptuła T, Rogalski J, Szczodrak J. Purification and characterization of an extracellular alpha-D-glucuronidase from Phlebia radiata. Prep Biochem Biotechnol 2005; 35:243-56. [PMID: 16109636 DOI: 10.1081/pb-200065648] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Alpha-D-glucuronidase was isolated from the culture filtrate of Phlebia radiata grown on wheat bran and purified to homogeneity by chromatographic methods. The final enzymic preparation was purified 65-fold with an activity yield of 58%; it showed a high level of specific activity (over 23,000 nkat/mg protein). The molecular and hydrolytic properties of the purified enzyme were studied. The secreted alpha-glucuronidase had a molecular weight of 110 kDa, as established by gel permeation chromatography (GP HPLC), had a determined pI just below 4.4, and was stable at pH 5.5 for prolonged times. The carbohydrate content in protein molecules was found to be 15%. The activity of alpha-D-glucuronidase peaked at pH 3,8 and 60 degrees C with aldouronic acids preparation as the substrate. The Michaelis-Menten constant (K(m)), the maximum reaction velocity (V(max)), and the activation energy (E(a)) were 0.18 mM, 0.13 microM/min and 5.91 kJ/mol, respectively. The alpha-glucuronidase was active mainly on small substituted xylooligomers. When this enzyme was used with endoxylanase for the degradation of oat xylan, synergistic effects were observed.
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Affiliation(s)
- Małgorzata Mierzwa
- Department of Biochemistry, Maria Curie-Skłodowska University, Lublin, Poland
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81
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Polizeli MLTM, Rizzatti ACS, Monti R, Terenzi HF, Jorge JA, Amorim DS. Xylanases from fungi: properties and industrial applications. Appl Microbiol Biotechnol 2005; 67:577-91. [PMID: 15944805 DOI: 10.1007/s00253-005-1904-7] [Citation(s) in RCA: 664] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 12/29/2004] [Accepted: 12/31/2004] [Indexed: 10/25/2022]
Abstract
Xylan is the principal type of hemicellulose. It is a linear polymer of beta-D-xylopyranosyl units linked by (1-4) glycosidic bonds. In nature, the polysaccharide backbone may be added to 4-O-methyl-alpha-D-glucuronopyranosyl units, acetyl groups, alpha-L-arabinofuranosyl, etc., in variable proportions. An enzymatic complex is responsible for the hydrolysis of xylan, but the main enzymes involved are endo-1,4-beta-xylanase and beta-xylosidase. These enzymes are produced by fungi, bacteria, yeast, marine algae, protozoans, snails, crustaceans, insect, seeds, etc., but the principal commercial source is filamentous fungi. Recently, there has been much industrial interest in xylan and its hydrolytic enzymatic complex, as a supplement in animal feed, for the manufacture of bread, food and drinks, textiles, bleaching of cellulose pulp, ethanol and xylitol production. This review describes some properties of xylan and its metabolism, as well as the biochemical properties of xylanases and their commercial applications.
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Affiliation(s)
- M L T M Polizeli
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto-Universidade de São Paulo, Av. Bandeirantes, 3900, Bairro Monte Alegre , 14040-901 Ribeirão Preto, São Paulo, Brazil.
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82
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Lin CC, Hsieh PC, Mau JL, Teng DF. Construction of an intergeneric fusion from Schizosaccharomyces pombe and Lentinula edodes for xylan degradation and polyol production. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2004.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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83
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Palonen H, Viikari L. Role of oxidative enzymatic treatments on enzymatic hydrolysis of softwood. Biotechnol Bioeng 2004; 86:550-7. [PMID: 15129438 DOI: 10.1002/bit.20135] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The impact of oxidative modification and partial removal of lignin by laccase-mediator treatments on the enzymatic hydrolysis of steam-pretreated softwood (SPS) was evaluated. Two mediators, N-hydroxy-N-phenylacetamide (NHA) and its acetylated precursor, were oxidized by the laccase from Trametes hirsuta, and their effects on the activity of cellulolytic enzymes and on the hydrolysis yield of SPS were examined. Both simultaneous and sequential combinations of laccase-mediator treatments with commercial cellulases increased the sugar yield in the enzymatic hydrolysis of SPS. The maximal increase was 21% when a sequential treatment was applied. Laccase treatment alone was also shown to improve hydrolysis. NHA oxidized by laccase inhibited significantly the cellulases of Trichoderma reesei, but the presence of the solid substrate protected the activities against oxidative inactivation. Surface analysis of the lignocellulosic substrate before and after the laccase and cellulase treatments revealed an enrichment of lignin and an increase of carboxylic groups on the surface of the hydrolysis residue.
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Affiliation(s)
- Hetti Palonen
- VTT Biotechnology, P.O. Box 1500, FIN-02044 VTT Espoo, Finland
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84
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Golan G, Shallom D, Teplitsky A, Zaide G, Shulami S, Baasov T, Stojanoff V, Thompson A, Shoham Y, Shoham G. Crystal structures of Geobacillus stearothermophilus alpha-glucuronidase complexed with its substrate and products: mechanistic implications. J Biol Chem 2003; 279:3014-24. [PMID: 14573597 DOI: 10.1074/jbc.m310098200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alpha-glucuronidases cleave the alpha-1,2-glycosidic bond between 4-O-methyl-d-glucuronic acid and short xylooligomers as part of the hemicellulose degradation system. To date, all of the alpha-glucuronidases are classified as family 67 glycosidases, which catalyze the hydrolysis via the investing mechanism. Here we describe several high resolution crystal structures of the alpha-glucuronidase (AguA) from Geobacillus stearothermophilus, in complex with its substrate and products. In the complex of AguA with the intact substrate, the 4-O-methyl-d-glucuronic acid sugar ring is distorted into a half-chair conformation, which is closer to the planar conformation required for the oxocarbenium ion-like transition state structure. In the active site, a water molecule is coordinated between two carboxylic acids, in an appropriate position to act as a nucleophile. From the structural data it is likely that two carboxylic acids, Asp(364) and Glu(392), activate together the nucleophilic water molecule. The loop carrying the catalytic general acid Glu(285) cannot be resolved in some of the structures but could be visualized in its "open" and "closed" (catalytic) conformations in other structures. The protonated state of Glu(285) is presumably stabilized by its proximity to the negative charge of the substrate, representing a new variation of substrate-assisted catalysis mechanism.
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Affiliation(s)
- Gali Golan
- Department of Inorganic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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85
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Purification and characterization of Aspergillus β-d-galactanases acting on β-1,4- and β-1,3/6-linked arabinogalactans. Carbohydr Polym 2003. [DOI: 10.1016/s0144-8617(02)00303-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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86
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Abstract
O-acetylated glucomannans were isolated from aspen and birch wood employing two different procedures and thereafter subjected to carbohydrate analysis by NMR spectroscopy and MALDI mass spectrometry. In one of the isolation procedures, acetone-extracted aspen or birch wood meal was extracted with dimethyl sulfoxide and then with hot water. Fractionation of the hemicellulose-containing extracts by size-exclusion chromatography was subsequently performed. In the other procedure, fractional precipitation with ethanol was used to isolate glucomannans from lyophilized process water produced by mechanical pulping of aspen. The aspen and birch glucomannans are O-acetylated at the C-2 or C-3 position of some of the mannose residues (random distribution), with a degree of acetylation of approx 0.3. In both cases the degree of polymerization was approx 16, indicating that low-molecular mass fractions of the glucomannans in hardwood have been isolated here.
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87
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88
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Perrone P, Hewage CM, Thomson AR, Bailey K, Sadler IH, Fry SC. Patterns of methyl and O-acetyl esterification in spinach pectins: new complexity. PHYTOCHEMISTRY 2002; 60:67-77. [PMID: 11985854 DOI: 10.1016/s0031-9422(02)00039-0] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Driselase-digestion of cell walls from suspension-cultures of spinach (Spinacia oleracea L.), followed by anion-exchange chromatography, gel-permeation chromatography, preparative paper chromatography and preparative paper electrophoresis, yielded ten uronic acid-containing products in addition to free galacturonic acid (GalA). These included 4-O-methylglucuronic acid, alpha-L-rhamnopyranosyl-(1-->4)-D-glucuronic acid and several oligosaccharides containing GalA residues. The structures were unambiguously determined by a combination of 1- and 2-dimensional NMR spectroscopic techniques. Five of the six homogalacturonan-derived oligosaccharides purified contained 3-O-acetyl-GalA residues; however, methyl-esterified GalA residues occurred adjacent to both 2-O-acetyl-GalA and 3-O-acetyl-GalA residues. An acetylated, rhamnogalacturonan-I-derived oligosaccharide that was purified also contained 3-O-acetyl-GalA residues. Taken together with published data, our findings indicate considerable diversity in the patterns of pectin esterification. The implications for the action of pectin esterases are discussed.
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Affiliation(s)
- Paola Perrone
- The Edinburgh Cell Wall Group, Institute of Cell and Molecular Biology, The University of Edinburgh, UK
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89
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Suresh C, Rus'd AA, Kitaoka M, Hayashi K. Evidence that the putative alpha-glucosidase of Thermotoga maritima MSB8 is a pNP alpha-D-glucuronopyranoside hydrolyzing alpha-glucuronidase. FEBS Lett 2002; 517:159-62. [PMID: 12062428 DOI: 10.1016/s0014-5793(02)02611-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The gene (agu) encoding p-nitrophenyl alpha-D-glucuronopyranoside (pNP-GUA) hydrolyzing alpha-glucuronidase of the hyperthermophilic bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. The recombinant enzyme was purified and characterized. The gene previously designated as putative alpha-glucosidase was found to code for a protein that had no alpha-glucosidase activity. It showed a rare activity profile with its ability to hydrolyze pNP-GUA, an activity not known in the alpha-glucuronidases from microbial sources. This is the first report on the occurrence of an alpha-glucuronidase which belongs to the family 4 of glycosyl hydrolases.
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Affiliation(s)
- Cuddapah Suresh
- Enzyme Laboratory, National Food Research Institute, Ibaraki, Tsukuba, Japan
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90
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Teleman A, Tenkanen M, Jacobs A, Dahlman O. Characterization of O-acetyl-(4-O-methylglucurono)xylan isolated from birch and beech. Carbohydr Res 2002; 337:373-7. [PMID: 11841818 DOI: 10.1016/s0008-6215(01)00327-5] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The structures of water-soluble birch and beech xylans, extracted from holocellulose using dimethyl sulfoxide, were determined employing 1H and 13C NMR spectroscopy together with chemical analysis. These polysaccharides were found to be O-acetyl-(4-O-methylglucurono)xylans containing one 4-O-methylglucuronic acid substituent for approximately every 15 D-xylose residues. The average degree of acetylation of the xylose residues in these polymers was 0.4. The presence of the structural element -->4)[4-O-Me-alpha-D-GlcpA-(1-->2)][3-O-Ac]-beta-D-Xylp-(1--> was demonstrated. Additional acetyl groups were present as substituents at C-2 and/or C-3 of the xylopyranosyl residues. Utilizing size-exclusion chromatography in combination with mass spectroscopy, the weight-average molar masses (and polydispersities) were shown to be 8000 (1.09) and 11,100 (1.08) for birch and beech xylan, respectively.
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Affiliation(s)
- Anita Teleman
- Swedish Pulp and Paper Research Institute, STFI, Box 5604, SE-114 86, Stockholm, Sweden.
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91
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Zaide G, Shallom D, Shulami S, Zolotnitsky G, Golan G, Baasov T, Shoham G, Shoham Y. Biochemical characterization and identification of catalytic residues in alpha-glucuronidase from Bacillus stearothermophilus T-6. ACTA ACUST UNITED AC 2001; 268:3006-16. [PMID: 11358519 DOI: 10.1046/j.1432-1327.2001.02193.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alpha-D-glucuronidases cleave the alpha-1,2-glycosidic bond of the 4-O-methyl-D-glucuronic acid side chain of xylan, as a part of an array of xylan hydrolyzing enzymes. The alpha-D-glucuronidase from Bacillus stearothermophilus T-6 was overexpressed in Escherichia coli using the T7 polymerase expression system. The purification procedure included two steps, heat treatment and gel filtration chromatography, and provided over 0.3 g of pure enzyme from 1 L of overnight culture. Based on gel filtration, the native protein is comprised of two identical subunits. Kinetic constants with aldotetraouronic acid as a substrate, at 55 degrees C, were a Km of 0.2 mM, and a specific activity of 42 U x mg(-1) (kcat = 54.9 s(-1)). The enzyme was most active at 65 degrees C, pH 5.5-6.0, in a 10-min assay, and retained 100% of its activity following incubation at 70 degrees C for 20 min. Based on differential scanning calorimetry, the protein denatured at 73.4 degrees C. Truncated forms of the enzyme, lacking either 126 amino acids from its N-terminus or 81 amino acids from its C-terminus, exhibited low residual activity, indicating that the catalytic site is located in the central region of the protein. To identify the potential catalytic residues, site-directed mutagenesis was applied on highly conserved acidic amino acids in the central region. The replacements Glu392-->Cys and Asp364-->Ala resulted in a decrease in activity of about five orders of magnitude, suggesting that these residues are the catalytic pair.
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Affiliation(s)
- G Zaide
- Department of Food Engineering and Biotechnology, Technion - Israel Institute of Technology, Haifa, Israel
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92
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Biely P, Hirsch J, la Grange DC, van Zyl WH, Prior BA. A chromogenic substrate for a beta-xylosidase-coupled assay of alpha-glucuronidase. Anal Biochem 2000; 286:289-94. [PMID: 11067752 DOI: 10.1006/abio.2000.4810] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
4-Nitrophenyl 2-(4-O-methyl-alpha-d-glucopyranuronosyl)-beta-d-xylopyranoside obtained on deesterification of 4-nitrophenyl 2-O-(methyl 4-O-methyl-alpha-d-glucopyranosyluronate)-beta-d-xylopyranoside (Hirsch et al., Carbohydr. Res. 310, 145-149, 1998) was found to be an excellent substrate for the measurement of hemicellulolytic alpha-glucuronidase activity. A new precise alpha-glucuronidase assay was developed by coupling the alpha-glucuronidase-catalyzed formation of 4-nitrophenyl beta-d-xylopyranoside with its efficient hydrolysis by beta-xylosidase. A recombinant strain of Saccharomyces cerevisiae, harboring and expressing the beta-xylosidase gene xlnD of Aspergillus niger under control of the alcohol dehydrogenase II promoter on a multicopy plasmid, was used as a source of beta-xylosidase. The activity values of beta-xylosidase in the assay required to achieve a steady-state rate of 4-nitrophenol formation shortly after starting the alpha-glucuronidase reaction were obtained both experimentally and by calculation using the kinetics of coupled enzyme reactions.
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Affiliation(s)
- P Biely
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 84238, Slovakia.
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