Phylogenetic variation in glycosidases and glycanases acting on plant cell wall polysaccharides, and the detection of transglycosidase and trans-β-xylanase activities

Wall polysaccharide chemistry varies phylogenetically, suggesting a need for variation in wall enzymes. Although plants possess the genes for numerous putative enzymes acting on wall carbohydrates, the activities of the encoded proteins often remain conjectural. To explore phylogenetic differences in demonstrable enzyme activities, we extracted proteins from 57 rapidly growing plant organs with three extractants, and assayed their ability to act on six oligosaccharides ‘modelling’ selected cell‐wall polysaccharides. Based on reaction products, we successfully distinguished exo‐ and endo‐hydrolases and found high taxonomic variation in all hydrolases screened: β‐d ‐xylosidase, endo‐(1→4)‐β‐d ‐xylanase, β‐d ‐mannosidase, endo‐(1→4)‐β‐d ‐mannanase, α‐d ‐xylosidase, β‐d ‐galactosidase, α‐l ‐arabinosidase and α‐l ‐fucosidase. The results, as GHATAbase, a searchable compendium in Excel format, also provide a compilation for selecting rich sources of enzymes acting on wall carbohydrates. Four of the hydrolases were accompanied, sometimes exceeded, by transglycosylase activities, generating products larger than the substrate. For example, during β‐xylosidase assays on (1→4)‐β‐d ‐xylohexaose (Xyl₆), Marchantia, Selaginella and Equisetum extracts gave negligible free xylose but approximately equimolar Xyl₅ and Xyl₇, indicating trans‐β‐xylosidase activity, also found in onion, cereals, legumes and rape. The yield of Xyl₉ often exceeded that of Xyl_7–8, indicating that β‐xylanase was accompanied by an endotransglycosylase activity, here called trans‐β‐xylanase, catalysing the reaction 2Xyl₆→ Xyl₃ + Xyl₉. Similar evidence also revealed trans‐α‐xylosidase, trans‐α‐arabinosidase and trans‐α‐arabinanase activities acting on xyloglucan oligosaccharides and (1→5)‐α‐l ‐arabino‐oligosaccharides. In conclusion, diverse plants differ dramatically in extractable enzymes acting on wall carbohydrate, reflecting differences in wall polysaccharide composition. Besides glycosidase and glycanase activities, five new transglycosylase activities were detected. We propose that such activities function in the assembly and re‐structuring of the wall matrix.     

Substrate complexation and aggregation influence the cyclodextrin glycosyltransferase (CGTase) catalyzed synthesis of alkyl glycosides

Bacillus macerans cyclodextrin glycosyltransferase (CGTase) was used to convert dodecyl-β-maltoside (DDM) to dodecyl-β-maltooctaoside (DDMO) using α-cyclodextrin (α-CD) or starch as glycosyl donors. At 300 mM α-CD, varied DDM concentration and 60 °C, the reaction obeyed Michaelis-Menten kinetics with a K_m value of 18 mM and a V_max value of 100 U/mg enzyme. However, at 25 mM α-CD the reaction rate decreased with increasing DDM concentration (5-50 mM), and when the α-CD concentration was varied at fixed DDM concentration an S shaped curve was obtained. The deviations from Michaelis-Menten kinetics were interpreted as being caused by formation of inclusion complexes between α-CD and DDM and by micellation of DDM. To achieve a high reaction rate, a high concentration of free α-CD is necessary, since α-CD in the form of a complex has low reactivity. When starch is used as glycosyl donor in the CGTase catalyzed alkyl glycoside elongation reaction, it is thus important to choose reaction conditions under which the cyclization of starch to α-CD is efficient.     

A TLC bioautographic method for the detection of α‐ and β‐glucosidase inhibitors in plant extracts

Introduction – Bioautographic assays using TLC play an important role in the search for active compounds from plants. A TLC assay has previously been established for the detection of β‐glucosidase inhibitors but not for α‐glucosidase. Nonetheless, α‐glucosidase inhibition is an important target for therapeutic agents against of type 2 diabetes and anti‐viral infections. Objective – To develop a TLC bioautographic method to detect α‐ and β‐glucosidase inhibitors in plant extracts. Methodology – The enzymes α‐ and β‐d ‐glucosidase were dissolved in sodium acetate buffer. After migration of the samples, the TLC plate was sprayed with enzyme solution and incubated at room temperature for 60 min in the case of α‐d ‐glucosidase, and 37°C for 20 min in the case of β‐d ‐glucosidase. For detection of the active enzyme, solutions of 2‐naphthyl‐α‐D‐glucopyranoside or 2‐naphthyl‐β‐D‐glucopyranoside and Fast Blue Salt were mixed at a ratio of 1 : 1 (for α‐d ‐glucosidase) or 1 : 4 (for β‐d ‐glucosidase) and sprayed onto the plate to give a purple background colouration after 2–5 min. Results – Enzyme inhibitors were visualised as white spots on the TLC plates. Conduritol B epoxide inhibited α‐d ‐glucosidase and β‐d ‐glucosidase down to 0.1 µg. Methanol extracts of Tussilago farfara and Urtica dioica after migration on TLC gave enzymatic inhibition when applied in amounts of 100 µg for α‐glucosidase and 50 µg for β‐glucosidase. Conclusion – The screening test was able to detect inhibition of α‐ and β‐glucosidases by pure reference substances and by compounds present in complex matrices, such as plant extracts. Copyright © 2009 John Wiley & Sons, Ltd.     

Altered product specificity of a cyclodextrin glycosyltransferase by molecular imprinting with cyclomaltododecaose

Cyclodextrin glycosyltransferases (CGTases), members of glycoside hydrolase family 13, catalyze the conversion of amylose to cyclodextrins (CDs), circular α‐(1,4)‐linked glucopyranose oligosaccharides of different ring sizes. The CD containing 12 α‐D‐glucopyranose residues was preferentially synthesized by molecular imprinting of CGTase from Paenibacillus sp. A11 with cyclomaltododecaose (CD₁₂) as the template molecule. The imprinted CGTase was stabilized by cross‐linking of the derivatized protein. A high proportion of CD₁₂ and larger CDs was obtained with the imprinted enzyme in an aqueous medium. The molecular imprinted CGTase showed an increased catalytic efficiency of the CD₁₂‐forming cyclization reaction, while decreased k_cat/K_m values of the reverse ring‐opening reaction were observed. The maximum yield of CD₁₂ was obtained when the imprinted CGTase was reacted with amylose at 40°C for 30 min. Molecular imprinting proved to be an effective means toward increase in the yield of large‐ring CDs of a specific size in the biocatalytic production of these interesting novel host compounds for molecular encapsulations. Copyright © 2010 John Wiley & Sons, Ltd.     

Inward facing conformations of the MetNI methionine ABC transporter: Implications for the mechanism of transinhibition

Two new crystal structures of the Escherichia coli high affinity methionine uptake ATP Binding Cassette (ABC) transporter MetNI, purified in the detergents cyclohexyl‐pentyl‐β‐D ‐maltoside (CY5) and n‐decyl‐β‐D ‐maltopyranoside (DM), have been solved in inward facing conformations to resolutions of 2.9 and 4.0 Å, respectively. Compared to the previously reported 3.7 Å resolution structure of MetNI purified in n‐dodecyl‐β‐D ‐maltopyranoside (DDM), the higher resolution of the CY5 data enabled significant improvements to the structural model in several regions, including corrections to the sequence registry, and identification of ADP in the nucleotide binding site. CY5 crystals soaked with selenomethionine established details of the methionine binding site in the C2 regulatory domain of the ABC subunit, including the displacement of the side chain of MetN residue methionine 301 by the exogenous ligand. When compared to the CY5 or DDM structures, the DM structure exhibits a significant repositioning of the dimeric C2 domains, including an unexpected register shift in the intermolecular β‐sheet hydrogen bonding between monomers, and a narrowing of the nucleotide binding space. The immediate proximity of the exogenous methionine binding site to the conformationally variable dimeric interface provides an indication of how methionine binding to the regulatory domains might mediate the phenomenon of transinhibition.     

Cyclodextrin production and genetic characterization of cyclodextrin glucanotranferase of <Emphasis Type="Italic">Paenibacillus graminis</Emphasis>

Paenibacillus graminis strains were described recently as cyclodextrin (CD) producers. Cyclodextrins are produced by cyclodextrin glucanotransferase (CGTase) which has not been characterized in P. graminis. Similar amounts of α- and β-CDs were produced by P. graminis (MC22.13) and P. macerans (LMD24.10^T). Primers were designed to sequence the gene encoding CGTase from P. graminis. A phylogenetic tree was constructed and P. graminis CGTase protein showed to be closer (79.4% protein identity) to P. macerans |P31835|. Hybridization studies suggested that the gene encoding CGTase is located in different positions in the genomes of P. macerans and P. graminis.     

Enzymatic synthesis of β‐glucosylglycerol using a continuous‐flow microreactor containing thermostable β‐glycoside hydrolase CelB immobilized on coated microchannel walls

β‐Glucosylglycerol (βGG) has potential applications as a moisturizing agent in cosmetic products. A stereochemically selective method of its synthesis is kinetically controlled enzymatic transglucosylation from a suitable donor substrate to glycerol as acceptor. Here, the thermostable β‐glycosidase CelB from Pyrococcus furiosus was used to develop a microstructured immobilized enzyme reactor for production of βGG under conditions of continuous flow at 70°C. Using CelB covalently attached onto coated microchannel walls to give an effective enzyme activity of 30 U per total reactor working volume of 25 µL, substrate conversion and formation of transglucosylation product was monitored in dependence of glucosyl donor (2‐nitrophenyl‐β‐D ‐glucoside (oNPGlc), 3.0 or 15 mM; cellobiose, 250 mM), the concentration of glycerol (0.25–1.0 M), and the average residence time (0.2–90 s). Glycerol caused a concentration‐dependent decrease in the conversion of the glucosyl donor via hydrolysis and strongly suppressed participation of the substrate in the reaction as glucosyl acceptor. The yields of βGG were ≥80% and ≈60% based on oNPGlc and cellobiose converted, respectively, and maintained up to near exhaustion of substrate (≥80%), giving about 120 mM (30 g/L) of βGG from the reaction of cellobiose and 1 M glycerol. The structure of the transglucosylation products, 1‐O‐β‐D ‐glucopyranosyl‐rac‐glycerol (79%) and 2‐O‐β‐D ‐glucopyranosyl‐sn‐glycerol (21%), was derived from NMR analysis of the product mixture of cellobiose conversion. The microstructured reactor showed conversion characteristics similar to those for a batchwise operated stirred reactor employing soluble CelB. The advantage of miniaturization to the microfluidic format lies in the fast characterization of full reaction time courses for a range of process conditions using only a minimum amount of enzyme. Biotechnol. Bioeng. 2009;103: 865–872. © 2009 Wiley Periodicals, Inc.     

Continuous production of cyclodextrins in an ultrafiltration membrane reactor,catalyzed by cyclodextrin glycosyltransferase from Bacillus circulans DF 9R

Cyclodextrins (CDs) are cyclic oligosaccharides of wide industrial application, whose synthesis is catalyzed by Cyclodextrin glycosyltransferase (CGTase) from starch. Here, CDs were produced using CGTase from Bacillus circulans DF 9R in continuous process and an ultrafiltration membrane reactor. The batch process was conducted as a control. This method allowed increasing the yield from 40 to 55.6% and the productivity from 26.1 to 99.5 mg of CD per unit of enzyme. The method also allowed obtaining a high‐purity product. The flow rate remained at 50% of its initial value after 24 h of process, improving the results described in the literature for starch hydrolysis processes. CGTase remained active throughout the process, which could be explained by the protective effect of the substrate and reaction products on CGTase stability. In addition, batch processes were developed using starches from different sources. We concluded that any of the starches studied could be used as substrate for CD production with similar yields and product specificity. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:695–699, 2015     

Simultaneous synthesis of 2‐phenylethanol and L‐homophenylalanine using aromatic transaminase with yeast Ehrlich pathway

2‐Phenylethanol is a widely used aroma compound with rose‐like fragrance and L ‐homophenylalanine is a building block of angiotensin‐converting enzyme (ACE) inhibitor. 2‐phenylethanol and L ‐homophenylalanine were synthesized simultaneously with high yield from 2‐oxo‐4‐phenylbutyric acid and L ‐phenylalanine, respectively. A recombinant Escherichia coli harboring a coupled reaction pathway comprising of aromatic transaminase, phenylpyruvate decarboxylase, carbonyl reductase, and glucose dehydrogenase (GDH) was constructed. In the coupled reaction pathway, the transaminase reaction was coupled with the Ehrlich pathway of yeast; (1) a phenylpyruvate decarboxylase (YDR380W) as the enzyme to generate the substrate for the carbonyl reductase from phenylpyruvate (i.e., byproduct of the transaminase reaction) and to shift the reaction equilibrium of the transaminase reaction, and (2) a carbonyl reductase (YGL157W) to produce the 2‐phenylethanol. Selecting the right carbonyl reductase showing the highest activity on phenylacetaldehyde with narrow substrate specificity was the key to success of the constructing the coupling reaction. In addition, NADPH regeneration was achieved by incorporating the GDH from Bacillus subtilis in the coupled reaction pathway. Based on 40 mM of L ‐phenylalanine used, about 96% final product conversion yield of 2‐phenylethanol was achieved using the recombinant E. coli. Biotechnol. Bioeng. 2009;102: 1323–1329. © 2008 Wiley Periodicals, Inc.     

Interconversion and disproportionation reaction among cyclodextrin homologues in an aqueous two-phase-forming solution

Interconversion reactions of cyclodextrin glycosyltransferase (CGTase) among cyclodextrin (CD) homologues were experimentally investigated using each CD as a substrate in an aqueous, two-phase-forming polymer solution of dextran and polyethylene glycol. Degradation rate of -CD was highest and that of -CD was lowest among -, - and -CD with Bacillus macerans CGTase. Degradation of each CD was accelerated with dextran, while decelerated with polyethylene glycol.     

Effect of 2‐hydroxypropyl‐β‐cyclodextrin on thermal stability and aggregation of glycogen phosphorylase b from rabbit skeletal muscle

The study of the kinetics of thermal aggregation of glycogen phosphorylase b (Phb) from rabbit skeletal muscles by dynamic light scattering at 48°C showed that 2‐hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) accelerated the aggregation process and induced the formation of the larger protein aggregates. The reason of the accelerating effect of HP‐β‐CD is destabilization of the protein molecule under action of HP‐β‐CD. This conclusion was supported by the data on differential scanning calorimetry and the kinetic data on thermal inactivation of Phb. It is assumed that destabilization of the Phb molecule is due to preferential binding of HP‐β‐CD to intermediates of protein unfolding in comparison with the original native state. The conclusion regarding the ability of the native Phb for binding of HP‐β‐CD was substantiated by the data on the enzyme inhibition by HP‐β‐CD. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 986–993, 2010.     

Effect of different substrates and their preliminary treatment on cyclodextrin production

Summary Various kinds of substrates were tested for cyclodextrin production with cyclodextrin glucanotransferase (CGTase) from Bacillus megaterium. The enzyme formed cyclodextrin from different kinds of starch, dextrins, amylose, and amylopectin. However, the highest degree of conversion was obtained from starch. Corn starch appeared to be the best substrate – the cyclodextrin yield was 50.9%. The effect of molecular mass and preliminary treatment of starch with α-amylase on the CD yield was investigated. It was proved that CGTase preferred native starch with high molecular mass and low dextrose equivalent. The preliminary treatment with α-amylase occurred to be inefficient and unnecessary since it did not lead to an increase in the CD yield. Some of the substrates were treated with pullulanase. The effect of debranching was highest in the case of corn starch: the cyclodextrin yield increased by 10%.     

Analogues of deltorphin I containing conformationally restricted amino acids in position 2: structure and opioid activity

New analogues of deltorphin I (DT I, Tyr‐d ‐Ala‐Phe‐Asp‐Val‐Val‐Gly‐NH₂), with the d ‐Ala residue in position 2 replaced by α‐methyl‐β‐azido(amino, 1‐pyrrolidinyl, 1‐piperidinyl or 4‐morpholinyl)alanine, were synthesized by a combination of solid‐phase and solution methods. All ten new analogues were tested for receptor affinity and selectivity to μ‐ and δ‐opioid receptors. The affinity of analogues containing (R) or (S)‐α‐methyl‐β‐azidoalanine in position 2 to δ‐receptors strongly depended on the chirality of the α,α‐disubstituted residue. Peptide II , containing (S)‐α‐methyl‐β‐azidoalanine in position 2, displayed excellent δ‐receptor selectivity with its δ‐receptor affinity being only three times lower than that of DT I. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Crystal structure of D‐glycero‐Β‐D‐manno‐heptose‐1‐phosphate adenylyltransferase from Burkholderia pseudomallei

The crystal structure of HldC from B. pseudomallei (BpHldC), the fourth enzyme of the heptose biosynthesis pathway, has been determined. BpHldC converts ATP and d ‐glycero‐β‐d ‐manno‐heptose‐1‐phosphate into ADP‐d ‐glycero‐β‐d ‐manno‐heptose and pyrophosphate. The crystal structure of BpHldC belongs to the nucleotidyltransferase α/β phosphodiesterase superfamily sharing a common Rossmann‐like α/β fold with a conserved T/HXGH sequence motif. The invariant catalytic key residues of BpHldC indicate that the core catalytic mechanism of BpHldC may be similar to that of other closest homologues. Intriguingly, a reorientation of the C‐terminal helix seems to guide open and close states of the active site for the catalytic reaction.     

Hydrolytic properties of a thermostable α‐l‐arabinofuranosidase from Caldicellulosiruptor saccharolyticus

Aims: To characterize of a thermostable recombinant α‐l ‐arabinofuranosidase from Caldicellulosiruptor saccharolyticus for the hydrolysis of arabino‐oligosaccharides to l ‐arabinose. Methods and Results: A recombinant α‐l ‐arabinofuranosidase from C. saccharolyticus was purified by heat treatment and Hi‐Trap anion exchange chromatography with a specific activity of 28·2 U mg^?1. The native enzyme was a 58‐kDa octamer with a molecular mass of 460 kDa, as measured by gel filtration. The catalytic residues and consensus sequences of the glycoside hydrolase 51 family of α‐l ‐arabinofuranosidases were completely conserved in α‐l ‐arabinofuranosidase from C. saccharolyticus. The maximum enzyme activity was observed at pH 5·5 and 80°C with a half‐life of 49 h at 75°C. Among aryl‐glycoside substrates, the enzyme displayed activity only for p‐nitrophenyl‐α‐l ‐arabinofuranoside [maximum k_cat/K_m of 220 m(mol l^?1)^?1 s^?1] and p‐nitrophenyl‐α‐l ‐arabinopyranoside. This substrate specificity differs from those of other α‐l ‐arabinofuranosidases. In a 1 mmol l^?1 solution of each sugar, arabino‐oligosaccharides with 2–5 monomer units were completely hydrolysed to l ‐arabinose within 13 h in the presence of 30 U ml^?1 of enzyme at 75°C. Conclusions: The novel substrate specificity and hydrolytic properties for arabino‐oligosaccharides of α‐l ‐arabinofuranosidase from C. saccharolyticus demonstrate the potential in the commercial production of l ‐arabinose in concert with endoarabinanase and/or xylanase. Significance and Impact of the Study: The findings of this work contribute to the knowledge of hydrolytic properties for arabino‐oligosaccharides performed by thermostable α‐l ‐arabinofuranosidase.     

The crystal structure of the Y140F mutant of ADP-l-glycero-d-manno-heptose 6-epimerase bound to ADP-��-d-mannose suggests a one base mechanism

Bacteria synthesize a wide array of unusual carbohydrate molecules, which they use in a variety of ways. The carbohydrate L ‐glycero‐D ‐manno‐heptose is an important component of lipopolysaccharide and is synthesized in a complex series of enzymatic steps. One step involves the epimerization at the C6″ position converting ADP‐D ‐glycero‐D ‐manno‐heptose into ADP‐L ‐glycero‐D ‐manno‐heptose. The enzyme responsible is a member of the short chain dehydrogenase superfamily, known as ADP‐L ‐glycero‐D ‐manno‐heptose 6‐epimerase (AGME). The structure of the enzyme was known but the arrangement of the catalytic site with respect to the substrate is unclear. We now report the structure of AGME bound to a substrate mimic, ADP‐β‐D ‐mannose, which has the same stereochemical configuration as the substrate. The complex identifies the key residues and allows mechanistic insight into this novel enzyme.     

Expression of Bacillus macerans cyclodextrin glucanotransferase gene in Saccharomyces cerevisiae

Cyclodextrin glucanotransferase (CGTase) gene of Bacillus macerans was subcloned down-stream of yeast ADH1 promoter and expressed in Saccharomyces cerevisiae. Most of the CGTase expressed was in the extracellular medium with a maximum activity of about 0.28 unit ml^–1 after 48 h cultivation. The recombinant CGTase was secreted as an N-linked-glycosylated form and predominantly produced -cyclodextrin from starch.     

Conformational flexibility of the glycosidase NagZ allows it to bind structurally diverse inhibitors to suppress β‐lactam antibiotic resistance

NagZ is an N‐acetyl‐β‐d ‐glucosaminidase that participates in the peptidoglycan (PG) recycling pathway of Gram‐negative bacteria by removing N‐acetyl‐glucosamine (GlcNAc) from PG fragments that have been excised from the cell wall during growth. The 1,6‐anhydromuramoyl‐peptide products generated by NagZ activate β‐lactam resistance in many Gram‐negative bacteria by inducing the expression of AmpC β‐lactamase. Blocking NagZ activity can thereby suppress β‐lactam antibiotic resistance in these bacteria. The NagZ active site is dynamic and it accommodates distortion of the glycan substrate during catalysis using a mobile catalytic loop that carries a histidine residue which serves as the active site general acid/base catalyst. Here, we show that flexibility of this catalytic loop also accommodates structural differences in small molecule inhibitors of NagZ, which could be exploited to improve inhibitor specificity. X‐ray structures of NagZ bound to the potent yet non‐selective N‐acetyl‐β‐glucosaminidase inhibitor PUGNAc (O‐(2‐acetamido‐2‐deoxy‐d ‐glucopyranosylidene) amino‐N‐phenylcarbamate), and two NagZ‐selective inhibitors – EtBuPUG, a PUGNAc derivative bearing a 2‐N‐ethylbutyryl group, and MM‐156, a 3‐N‐butyryl trihydroxyazepane, revealed that the phenylcarbamate moiety of PUGNAc and EtBuPUG completely displaces the catalytic loop from the NagZ active site to yield a catalytically incompetent form of the enzyme. In contrast, the catalytic loop was found positioned in the catalytically active conformation within the NagZ active site when bound to MM‐156, which lacks the phenylcarbamate extension. Displacement of the catalytic loop by PUGNAc and its N‐acyl derivative EtBuPUG alters the active site conformation of NagZ, which presents an additional strategy to improve the potency and specificity of NagZ inhibitors.     

Enantiomeric Separation of 13 New Amphetamine‐Like Designer Drugs by Capillary Electrophoresis,Using Modified‐‐Cyclodextrins

An easy‐to‐prepare chiral CE method for the enantiomeric separation of 13 new amphetamine‐like designer drugs, using CDs as chiral selectors, was developed. Sulfated‐β‐CD was found to be the best chiral selector among the three used (sulfated‐β‐CD, caroboxymethyl‐β‐CD, dimethyl‐β‐CD). The separation of the analytes was achieved in a fused‐silica gel capillary at 20 °C using an applied voltage of +25 kV. The optimized background electrolyte consisted of 63.5 mM H₃PO₄ and 46.9 mM NaOH in water. Several electrophoretic parameters such as CD type, CD concentration (1 ? 40 mg/mL), buffer pH (2.6, 3.6, 5.0, 6.0), length of the capillary (70 ? 40 cm total length), amount of the organic solvent (methanol and acetonitrile) were investigated and optimized. Chirality 25:617–621, 2013. © 2013 Wiley Periodicals, Inc.     

Structural analysis of CPF_2247, a novel α-amylase from Clostridium perfringens

CPF_2247 from Clostridium perfringens ATCC 13124 was identified as a putative carbohydrate‐active enzyme by its low sequence identity to endo‐β‐1,4‐glucanases belonging to family 8 of the glycoside hydrolase classification. The X‐ray crystal structure of CPF_2247 determined to 2.0 Å resolution by single‐wavelength anomalous dispersion using seleno‐methionine‐substituted protein revealed an (α/α)₆ barrel fold. A large cleft on the surface of the protein contains residues that are structurally conserved with key elements of the catalytic machinery in clan GH‐M glycoside hydrolases. Assessment of CPF_2247 as a carbohydrate‐active enzyme disclosed α‐glucanase activity on amylose, glycogen, and malto‐oligosaccharides. Proteins 2011;. © 2011 Wiley‐Liss, Inc.