Versatile high resolution oligosaccharide microarrays for plant glycobiology and cell wall research.
Pedersen, H. L., Fangel, J. U., McCleary, B., Ruzanski, C., Rydahl, M. G., Ralet, M. C., Farkas, V., Von Schantz, L., Marcus, S. E., Andersen, M.C. F., Field, R., Ohlin, M., Knox, J. P., Clausen, M. H. & Willats, W. G. T. (2012). Journal of Biological Chemistry, 287(47), 39429-39438.
Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.
Purification and characterization of two β-mannanases from Trichoderma reesei.
Stålbrand, H., Siika-aho, M., Tenkanen, M. & Viikari, L. (1993). Journal of Biotechnology, 29(3), 229-242.
Five enzymes with mannanase activity were separated from Trichoderma reesei culture filtrate using analytical isoelectric focusing and subsequently detected with the zymogram technique. The crude enzymes had isoelectric points in the range of 3.6–6.5. Two of the mannanases with pI values of 4.6 and 5.4 were purified using ion-exchange chromatography, affinity chromatography and chromatofocusing. The molecular weights determined with SDS-PAGE were 51 000 (mannanase pI 4.6) and 53 000 (mannanase pI 5.4). The two enzymes had similar properties with respect to pH optimae and pH stabilities. Both mannanases hydrolyzed ivory nut mannan mainly to mannotriose and mannobiose. The specific activities (against locust bean gum) of the purified enzymes were 1860 and 1430 nkat mg-1 for the pI 4.6 and pI 5.4 mannanases, respectively.
New microbial mannan catabolic pathway that involves a novel mannosylglucose phosphorylase.
Senoura, T., Ito, S., Taguchi, H., Higa, M., Hamada, S., Matsui, H., Ozawa, T., Jin, S., Watanabe, J., Wasaki, J. & Ito, S. (2011). Biochemical and Biophysical Research Communications, 408(4), 701-706.
The consecutive genes BF0771–BF0774 in the genome of Bacteroidesfragilis NCTC 9343 were found to constitute an operon. The functional analysis of BF0772 showed that the gene encoded a novel enzyme, mannosylglucose phosphorylase that catalyzes the reaction, 4-O-β-
D-mannopyranosyl-D-glucose + Pi → mannose-1-phosphate + glucose. Here we propose a new mannan catabolic pathway in the anaerobe, which involves 1,4-β-mannanase (BF0771), a mannobiose and/or sugar transporter (BF0773), mannobiose 2-epimerase (BF0774), and mannosylglucose phosphorylase (BF0772), finally progressing to glycolysis. This pathway is distributed in microbes such as Bacteroides, Parabacteroides, Flavobacterium, and Cellvibrio.
Discovery of β-1, 4-D-Mannosyl-N-acetyl-D-glucosamine Phosphorylase Involved in the Metabolism of N-Glycans.
Nihira, T., Suzuki, E., Kitaoka, M., Nishimoto, M., Ohtsubo, K. I. & Nakai, H. (2013). Journal of Biological Chemistry, 288(38), 27366-27374.
A gene cluster involved in N-glycan metabolism was identified in the genome of Bacteroides thetaiotaomicron VPI-5482. This gene cluster encodes a major facilitator superfamily transporter, a starch utilization system-like transporter consisting of a TonB-dependent oligosaccharide transporter and an outer membrane lipoprotein, four glycoside hydrolases (α-
mannosidase, β-N-acetylhexosaminidase, exo-α-sialidase, and endo-β-N-acetylglucosaminidase), and a phosphorylase (BT1033) with unknown function. It was demonstrated that BT1033 catalyzed the reversible phosphorolysis of β-1,4-D-mannosyl-N-acetyl-D-glucosamine in a typical sequential Bi Bi mechanism. These results indicate that BT1033 plays a crucial role as a key enzyme in the N-glycan catabolism where β-1,4-D-mannosyl-N-acetyl-D-glucosamine is liberated from N-glycans by sequential glycoside hydrolase-catalyzed reactions, transported into the cell, and intracellularly converted into α-D-mannose 1-phosphate and N-acetyl-D-glucosamine. In addition, intestinal anaerobic bacteria such as Bacteroides fragilis, Bacteroides helcogenes, Bacteroides salanitronis, Bacteroides vulgatus, Prevotella denticola, Prevotella dentalis, Prevotella melaninogenica, Parabacteroides distasonis, and Alistipes finegoldii were also suggested to possess the similar metabolic pathway for N-glycans. A notable feature of the new metabolic pathway for N-glycans is the more efficient use of ATP-stored energy, in comparison with the conventional pathway where β-mannosidase and ATP-dependent hexokinase participate, because it is possible to directly phosphorylate the D-mannose residue of β-1,4-D-mannosyl-N-acetyl-D-glucosamine to enter glycolysis. This is the first report of a metabolic pathway for N-glycans that includes a phosphorylase. We propose 4-O-β-D-mannopyranosyl-N-acetyl-D-glucosamine:phosphate α-D-mannosyltransferase as the systematic name and β-1,4-D-mannosyl-N-acetyl-D-glucosamine phosphorylase as the short name for BT1033.
Softwood hemicellulose-degrading enzymes from Aspergillus niger: Purification and properties of a β-mannanase.
Ademark, P., Varga, A., Medve, J., Harjunpää, V., Drakenberg, T., Tjerneld, F. & Stålbrand, H. (1998). Journal of Biotechnology, 63(3), 199-210.
The enzymes needed for galactomannan hydrolysis, i.e. β-mannanase, α-galactosidase and β-mannosidase, were produced by the filamentous fungus Aspergillus niger. The β-mannanase was purified to electrophoretic homogeneity in three steps using ammonium sulfate precipitation, anion-exchange chromatography and gel filtration. The purified enzyme had an isoelectric point of 3.7 and a molecular mass of 40 kDa. Ivory nut mannan was degraded mainly to mannobiose and mannotriose when incubated with the β-mannanase. Analysis by 1H NMR spectroscopy during hydrolysis of mannopentaose showed that the enzyme acts by the retaining mechanism. The N-terminus of the purified A. niger β-mannanase was sequenced by Edman degradation, and comparison with Aspergillus aculeatus β-mannanase indicated high identity. The enzyme most probably lacks a cellulose binding domain since it was unable to adsorb on cellulose.
Substrate specificity of cellobiose dehydrogenase from Phanerochaete chrysosporium.
Henriksson, G., Sild, V., Szabó, I. J., Pettersson, G. & Johansson, G. (1998). Biochimica et Biophysica Acta (BBA)-Protein Structure and Molecular Enzymology, 1383(1), 48-54.
Substrate structural mapping suggests that the catalytic site of cellobiose dehydrogenase from Phanerochaete chrysosporium forms a narrow cave with two hexose binding subsites. Kinetic data also show that β-di or oligosaccharides are favored electron donors with respect to both KM andkcat. Surprisingly, thiocellobiose showed an even higher kcat than cellobiose, although the KM value was somewhat higher. The CDH was purified using an updated protocol.
Molecular and biochemical characterization of endo-β-mannanases from germinating coffee (Coffea Arabica) grains.
Marraccini, P., Rogers, J. W., Allard, C., André, M. L., Caillet, V., Lacoste, N., Lausamme, F. & Michaux, S. (2001). Planta, 213(2), 296-308.
The activity of endo-β-mannanase ([1→4]-β-mannan endohydrolase EC 184.108.40.206) is likely to be central to the metabolism of cell wall mannans during the germination of grains of coffee (Coffea spp.). In the present paper, we report the cloning and sequencing of two endo-β-mannanase cDNAs (manA and manB) by different strategies from Coffea arabica L. The manA cDNA was obtained by the use of oligonucleotides homologous to published sequences of other endo-β-mannanases and manB by the use of oligonucleotides deduced from a purified enzyme from coffee. ManA and B proteins share about 56% sequence homology and include highly conserved regions found in other mannan endohydrolases. Purification of the activity by chromatography followed by separation by two-dimensional electrophoresis and amino acid sequencing demonstrated the existence of at least seven isomers of the ManB form. The existence of multiple manB genes was also indicated by Southern analysis, whereas only one or two gene copies were detected for manA. Northern hybridizations with manA- and manB-specific probes showed that mRNA transcripts for both cDNAs were present at the same periods of bean germination with transcript peaks at 20 days after imbibition of water (DAI). Transcripts were not detected during grain maturation or in the other tissues such as roots, stems, flowers and leaves. The peak endo-β-mannanase activity occurred at approximately 28 DAI and was not detected in grains prior to imbibition. Activity and mRNA levels appeared to be tightly co-ordinated. Tests of substrate specificity with the purified ManB enzyme showed that activity required a minimum of five mannose units to function efficiently.
Model for random hydrolysis and end degradation of linear polysaccharides: Application to the thermal treatment of mannan in solution.
Nattorp, A., Graf, M., Spühler, C. & Renken, A. (1999). Industrial & Engineering Chemistry Research, 38(8), 2919-2926.
The kinetics for homogeneous hydrolysis of mannan is studied in a batch reactor at temperatures from 160 to 220°C. A formate buffer ensures a pH of 3.8−4.0, measured at 25°C. Samples are analyzed for oligosaccharides up to a degree of polymerization of 6 and also for the total amount of mannose after acid hydrolysis. A mathematical model with two reactions (1, random hydrolysis of the glucosidic bonds; 2, degradation of the reducing end of the molecule) describes accurately the time course of oligosaccharides. Optimized rate constants follow closely an Arrhenius relationship, with the degradation having a higher activation energy (140 kJ/mol) than the hydrolysis (113 kJ/mol). The mathematical model has the advantage that production of small molecules is independent of the initial chain-length distribution as long as the average initial chain length is some 5 times longer than the largest species measured. It can be applied to first-order depolymerization of other linear polymers with one link type in order to determine reaction rate constants or make predictions about molecular weight distribution on the base of known reaction rate constants.
A Novel β-1, 4-mannanase Isolated from Paenibacillus polymyxa KT551.
Hori, K., Kawabata, Y., Nakazawa, Y., Nishizawa, M. & Toeda, K. (2014). Food Science and Technology Research, 20(6), 1261-1265.
A β-1,4-mannanase producing bacterium was isolated from soil collected in Akita Prefecture, Japan. The bacterium was identified as Paenibacillus polymyxa KT551 and was shown to produce a novel β-1,4-mannanase. The novelty of the enzyme was established by its N-terminal amino acid sequence, molecular weight and isoelectric point. The isolated β-1,4-mannanase showed activity against mannotetraose, mannopentaose and mannohexaose to produce mannobiose, mannotriose and mannotetraose. However, the enzyme exhibited no activity against mannobiose and mannotriose. Moreover, the crude enzyme preparation of the bacterium had no or minimal β-mannosidase or α-galactosidase activity. Therefore, the enzyme preparation from P. polymyxa KT551 holds potential for the efficient production of mannooligosaccharides from natural resources of galactomannans.
A comparison between a yeast cell wall extract (Bio-Mos®) and palm kernel expeller as mannan-oligosac-charides sources on the performance and ileal microbial population of broiler chickens.
Navidshad, B., Liang, J. B., Jahromi, M. F., Akhlaghi, A. & Abdullah, N. (2015). Italian Journal of Animal Science, 14(1), 3452.
The present study was conducted to determine the effect of a yeast cell wall extract (Bio-Mos) and palm kernel expeller (PKE) on the performance, nutrient digestibility, and ileal bacteria population of broiler chickens. A total of 60 1-d-old male broiler chicks (Cobb 500) were fed one of the 3 isonitrogenous and isocaloric diet including a control diet, or a control diet supplemented with 2 g/kg Bio-Mos (1-42 d), and for the third group, the control diet at 1-28 d following a diet containing 200 g/kg of an enzymatically-treated PKE at 29-42 d. The weight gains of birds fed the PKE containing diet (96.17 g/d) were less than other groups (109.10 and 104.42 g/d for the Bio-Mos and control diet, respectively) (P<0.05). Dietary inclusion of PKE increased bird’s feed intake (214.45 g/d) and feed conversion ratio (FCR) (2.23) than the Bio-Mos diet (194.87 and 1.79 g/d for feed intake and FCR, respectively) (P<0.05). The PKE diet had lower digestibility coefficients for dry matter (83.37%), ash and crude protein (78.63%) than the PKE free diets (P<0.05). As a ratio of the ileal total bacteria, there were no differences in the ileal population of Lactobacilli and Enterococcus genus or Enterobacteriaceae among the experimental groups (P>0.05), but the birds fed PKE or Bio-Mos containing diets had a lower population of Escherichia colithan the control group (P<0.05). The results showed that PKE potentially has a prebiotic property for chicken; however, a 200 g/kg dietary inclusion rate of PKE is not commercially recommendable because of its negative effects on the nutrients digestibility.
Functional reassignment of Cellvibrio vulgaris EpiA to cellobiose 2-epimerase and an evaluation of the biochemical functions of the 4-O-β-D-mannosyl-D-glucose phosphorylase-like protein, UnkA.
Saburi, W., Tanaka, Y., Muto, H., Inoue, S., Odaka, R., Nishimoto, M., Kitaoka, M. & Mori, H. (2015). Bioscience, Biotechnology, and Biochemistry, 79(6), 969-977.
The aerobic soil bacterium Cellvibrio vulgaris has a β-mannan-degradation gene cluster, including unkA, epiA, man5A, and aga27A. Among these genes, epiA has been assigned to encode an epimerase for converting D-mannose to D-glucose, even though the amino acid sequence of EpiA is similar to that of cellobiose 2-epimerases (CEs). UnkA, whose function currently remains unknown, shows a high sequence identity to 4-O-β-D-mannosyl-D-glucose phosphorylase. In this study, we have investigated CE activity of EpiA and the general characteristics of UnkA using recombinant proteins from Escherichia coli. Recombinant EpiA catalyzed the epimerization of the 2-OH group of sugar residue at the reducing end of cellobiose, lactose, and β-(1→4)-mannobiose in a similar manner to other CEs. Furthermore, the reaction efficiency of EpiA for β-(1→4)-mannobiose was 5.5 × 104-fold higher than it was for D-mannose. Recombinant UnkA phosphorolyzed β-D-mannosyl-(1→4)-D-glucose and specifically utilized D-glucose as an acceptor in the reverse reaction, which indicated that UnkA is a typical 4-O-β-D-mannosyl-D-glucose phosphorylase. Functional analysis of Cellvibrio vulgaris EpiA and UnkA proteins suggested that this bacterium degrades β-(1→4)-mannobiose through the epimerization and phosphorolysis.
High-level expression and characterization of a thermophilic β-mannanase from Aspergillus niger in Pichia pastoris.
Yu, S., Li, Z., Wang, Y., Chen, W., Fu, L., Tang, W., Chen, C., Liu, Y., Zhang, X. & Ma, L. (2015). Biotechnology Letters, 37(9), 1853-1859.
Objectives: A novel, high-level expression, thermostable mannan endo-1,4-β-mannosidase is urgently needed for industrial applications. Results: The mannan endo-1,4-β-mannosidase gene (MAN) from Aspergillus niger CBS 513.88 was optimized based on the codon usage bias in Pichia pastoris and synthesized by overlapping PCR to produce MAN-P. It was expressed in P. pastoris GS115 from a constitutive expression vector pHBM-905 M. MAN-P reached 594 mg/l in shake-flasks after 192 h induction. On production in a 5 l fermenter, the yield of MAN-P reached ~3.5 mg/ml and the enzyme activity was 1612 U/ml. The enzyme exhibited a maximum activity of 3049 U/ml at 80°C and retained 60 % enzyme activity at 80°C for 2 h. The pH optimum was 4.5 and the enzyme was stable over the pH range 1.5-11. Conclusion: The thermostability of MAN-P is higher than other known fungal mannanases and the expression and thermophilic properties make MAN-P useful for industrial applications.
A novel thermostable GH5_7 β-mannanase from Bacillus pumilus GBSW19 and its application in manno-oligosaccharides (MOS) production.
Zang, H., Xie, S., Wu, H., Wang, W., Shao, X., Wu, L., Rajer, F. U. & Gao, X. (2015). Enzyme and microbial technology, 78, 1-9.
A novel thermostable mannanase from a newly isolated Bacillus pumilus GBSW19 has been identified, expressed, purified and characterized. The enzyme shows a structure comprising a 28 amino acid signal peptide, a glycoside hydrolase family 5 (GH5) catalytic domain and no carbohydrate-binding module. The recombinant mannanase has molecular weight of 45 kDa with an optimal pH around 6.5 and is stable in the range from pH 5-11. Meanwhile, the optimal temperature is around 65°C, and it retains 50% relative activity at 60°C for 12 h. In addition, the purified enzyme can be activated by several ions and organic solvents and is resistant to detergents. Bpman5 can efficiently convert locus bean gum to mainly M2, M3 and M5, and hydrolyze manno-oligosaccharides with a minimum DP of 3. Further exploration of the optimum condition using HPLC to prepare oligosaccharides from locust bean gum was obtained as 10 mg/ml locust bean gum incubated with 10 U/mg enzyme at 50°C for 24 h. By using this enzyme, locust bean gum can be utilized to generate high value-added oligosaccharides with a DP of 2-6.
An Aspergillus nidulans GH26 endo-β-mannanase with a novel degradation pattern on highly substituted galactomannans.
von Freiesleben, P., Spodsberg, N., Blicher, T. H., Anderson, L., Jørgensen, H., Stålbrand, H., Meyer, A. S. & Krogh, K. B. (2016). Enzyme and Microbial Technology, 83, 68-77.
The activity and substrate degradation pattern of a novel Aspergillus nidulans GH26 endo-β-mannanase (AnMan26A) was investigated using two galactomannan substrates with varying amounts of galactopyranosyl residues. The AnMan26A was characterized in parallel with the GH26 endomannanase from Podospora anserina (PaMan26A) and three GH5 endomannanases from A. nidulans and Trichoderma reesei (AnMan5A, AnMan5C and TrMan5A). The initial rates and the maximal degree of enzymatically catalyzed conversion of locust bean gum and guar gum galactomannans were determined. The hydrolysis product profile at maximal degree of conversion was determined using DNA sequencer-Assisted Saccharide analysis in High throughput (DASH). This is the first reported use of this method for analyzing galactomannooligosaccharides. AnMan26A and PaMan26A were found to have a novel substrate degradation pattern on the two galactomannan substrates. On the highly substituted guar gum AnMan26A and PaMan26A reached 35-40% as their maximal degree of conversion whereas the three tested GH5 endomannanases only reached 8-10% as their maximal degree of conversion. α-Galactosyl-mannose was identified as the dominant degradation product resulting from AnMan26A and PaMan26A action on guar gum, strongly indicating that these two enzymes can accommodate galactopyranosyl residues in the -1 and in the +1 subsite. The degradation of α-64-63-di-galactosyl-mannopentaose by AnMan26A revealed accommodation of galactopyranosyl residues in the -2, -1 and +1 subsite of the enzyme. Accommodation of galactopyranosyl residues in subsites -2 and +1 has not been observed for other characterized endomannanases to date. Docking analysis of galactomannooligosaccharides in available crystal structures and homology models supported the conclusions drawn from the experimental results. This newly discovered diversity of substrate degradation patterns demonstrates an expanded functionality of fungal endomannanases, than hitherto reported.
Two-stage hot-water extraction of galactoglucomannans from spruce wood.
Pranovich, A., Holmbom, B. & Willför, S. (2016). Journal of Wood Chemistry and Technology, 36(2), 140-156.
In order to preserve the polymeric structure and the acetylation degree of extracted galactoglucomannans and, at the same time, achieve high yield, ground spruce wood was subjected to a series of sequential two-stage extractions with an Accelerated Solvent Extraction (ASE) apparatus using plain water at 170 deg;C. The total combined extraction time was one hour in all the extractions. The total yield of the dissolved material after 1 h extraction was almost the same, about 25% of the wood, irrespective of the time ratios between the first and the second extractions. The yield of hemicellulose high polymers with the weight average molar mass of 8-10 kDa during the first extraction had a maximum at 20 min extraction time, amounting to about 7% on dry wood basis, and comprising about half of the total extract. Along with the progress of the extraction, the molar mass of the hemicelluloses decreased and hemicellulose-derived low polymers with the weight average molar mass of 6-2 kDa became dominating. The extracted substances were fractionated, mainly according to their molar mass, by sequential precipitation with ethanol, acetone, and methyl tert-butyl ether (MTBE). The hemicelluloses with some amount of pectins comprised 83-90% of the precipitated polymeric material and the content of galactoglucomannans was about 80%.
Biochemical characterization of an acidophilic β-mannanase from Gloeophyllum trabeum CBS900. 73 with significant transglycosylation activity and feed digesting ability.
Wang, C., Zhang, J., Wang, Y., Niu, C., Ma, R., Wang, Y., Bai, Y., Luo, H. & Yao, B. (2016). Food Chemistry, 197, 474-481.
Acidophilic β-mannanases have been attracting much attention due to their excellent activity under extreme acidic conditions and significant industrial applications. In this study, a β-mannanase gene of glycoside hydrolase family 5, man5A, was cloned from Gloeophyllum trabeum CBS900.73, and successfully expressed in Pichia pastoris. Purified recombinant Man5A was acidophilic with a pH optimum of 2.5 and exhibited great pH adaptability and stability (>80% activity over pH 2.0-6.0 and pH 2.0-10.0, respectively). It had a high specific activity (1356 U/mg) against locust bean gum, was able to degrade galactomannan and glucomannan in a classical four-site binding mode, and catalyzed the transglycosylation of mannotetrose to mannooligosaccharides with higher degree of polymerization. Besides, it had great resistance to pepsin and trypsin and digested corn-soybean meal based diet in a comparable way with a commercial β-mannanase under the simulated gastrointestinal conditions of pigs. This acidophilic β-mannanase represents a valuable candidate for wide use in various industries, especially in the feed.
From native malt to pure starch-Development and characterization of a purification procedure for modified starch.
Rittenauer, M., Kolesnik, L., Gastl, M. & Becker, T. (2016). Food Hydrocolloids, 56, 50-57.
Starch characteristics influence the gelatinization process, which is an important prerequisite for the saccharification required in many industrial processes. In order to determine these characteristics in barley malt, an adapted purification procedure allowing to preserve the native starch composition and simultaneously segregating the amylolytic enzymes which were formed during the germination is indispensable. Therefore, this research aimed to develop a method based on a combination of dry milling, micro-sieving and density gradient centrifugation. The impact on the starch characteristics was evaluated for three germinated barley varieties. The purified starches showed starch contents greater than 90% and proteins contents less than 0.4%. Yields ranged from 40.3 to 48.6%, depending on the variety. Considering the starch properties, the amylose/amylopectin ratio was not modified during the purification. The circularity of the granules as well as the ratio of A- and B-type granules remained constant. The particle size distribution of A-granules was not shifted, B-granules with a specific diameter of 5-10 µm were slightly reduced in dependency of the native granule composition. The highest impact could be observed on the amylolytic enzymes, which were completely segregated regardless of their initial value. The standard deviation of repeatability was less than 5%, except for the determination of B-type particle size distribution (7%). The newly developed procedure supplements existing isolation methods of unmalted grains by enabling the purification of germinated barley in a reproducible manner, without altering the native starch properties and by providing pure starch free of amylolytic activity.
An extremely alkaline mannanase from Streptomyces sp. CS428 hydrolyzes galactomannan producing series of mannooligosaccharides.
Pradeep, G. C., Cho, S. S., Choi, Y. H., Choi, Y. S., Jee, J. P., Seong, C. N. & Yoo, J. C. (2016). World Journal of Microbiology and Biotechnology, 32(5), 1-9.
An alkaline-thermostable mannanase from Streptomyces sp. CS428 was produced, purified, and biochemically characterized. The extracellular mannanase (Mn428) was purified to homogeneity with 12.4 fold, specific activity of 2406.7 U/mg, and final recovery of 37.6 %. The purified β-mannanase was found to be a monomeric protein with a molecular mass of approximately 35 kDa as analyzed by SDS-PAGE and zymography. The first N-terminal amino acid sequences of mannanase enzyme were HIRNGNHQLPTG. The optimal temperature and pH for enzyme were 60°C and 12.5, respectively. The mannanase activities were significantly affected by the presence of metal ions, modulators, and detergents. Km and Vmax values of Mn428 were 1.01 ± 3.4 mg/mL and 5029 ± 85 µmol/min mg, respectively when different concentrations (0.6-10 mg/mL) of locust bean gum galactomannan were used as substrate. The substrate specificity of enzyme showed its highest specificity towards galactomannan which was further hydrolyzed to produce mannose, mannobiose, mannotriose, and a series of mannooligosaccharides. Mannooligosaccharides can be further converted to ethanol production, thus the purified β-mannanase isolated from Streptomyces sp. CS428 was found to be attractive for biotechnological applications.
Characterisation of a novel cellobiose 2‐epimerase from thermophilic Caldicellulosiruptor obsidiansis for lactulose production.
Chen, Q., Levin, R., Zhang, W., Zhang, T., Jiang, B., Stressler, T., Fischer, L. & Mu, W. (2017). Journal of the Science of Food and Agriculture, 97(10), 3095-3105.
BACKGROUND: Lactulose, a bioactive lactose derivative, has been widely used in food and pharmaceutical industries. Isomerisation of lactose to lactulose by cellobiose 2-epimerase (CE) has recently attracted increasing attention, since CE produces lactulose with high yield from lactose as a single substrate. In this study, a new lactulose-producing CE from Caldicellulosiruptor obsidiansis was extensively characterised. RESULTS: The recombinant enzyme exhibited maximal activity at pH 7.5 and 70°C. It displayed high thermostability with Tm of 86.7°C. The half-life was calculated to be 8.1, 2.8 and 0.6 h at 75, 80, and 85°C, respectively. When lactose was used as substrate, epilactose was rapidly produced in a short period, and afterwards both epilactose and lactose were steadily isomerised to lactulose, with a final ratio of 35:11:54 for lactose:epilactose:lactulose. When the reverse reaction was investigated using lactulose as substrate, both lactose and epilactose appeared to be steadily produced from the start. CONCLUSION: The recombinant CE showed both epimerisation and isomerisation activities against lactose, making it an alternative promising biocatalyst candidate for lactulose production.
Mannan endo-1, 4-β-mannosidase from Kitasatospora sp. isolated in Indonesia and its potential for production of mannooligosaccharides from mannan polymers.
Rahmani, N., Kashiwagi, N., Lee, J., Niimi-Nakamura, S., Matsumoto, H., Kahar, P., Lisdiyanti, P., Yopi, Prasetya, B., Ogino, C. & Kondo, A. (2017). AMB Express, 7(1), 100.
Mannan endo-1,4-β-mannosidase (commonly known as β-mannanase) catalyzes a random cleavage of the β-D-1,4-mannopyranosyl linkage in mannan polymers. The enzyme has been utilized in biofuel production from lignocellulose biomass, as well as in production of mannooligosaccharides (MOS) for applications in feed and food industries. We aimed to obtain a β-mannanase, for such mannan polymer utilization, from actinomycetes strains isolated in Indonesia. Strains exhibiting high mannanase activity were screened, and one strain belonging to the genus Kitasatospora was selected. We obtained a β-mannanase from this strain, and an amino acid sequence of this Kitasatospora β-mannanase showed a 58-71% similarity with the amino acid sequences of Streptomyces β-mannanases. The Kitasatospora β-mannanase showed a significant level of activity (944 U/mg) against locust bean gum (0.5% w/v) and a potential for oligosaccharide production from various mannan polymers. The β-mannanase might be beneficial particularly in the enzymatic production of MOS for applications of mannan utilization.