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β-Amylase (Barley)

Product code: E-BARBL-50KU



50,000 Units

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Content: 20,000 Units or 50,000 Units
Shipping Temperature: Ambient
Storage Temperature: 2-8oC
Formulation: In 3.2 M ammonium sulphate
Physical Form: Suspension
Stability: > 1 year under recommended storage conditions
Enzyme Activity: β-Amylase
EC Number:
CAZy Family: GH14
CAS Number: 9000-91-3
Synonyms: beta-amylase; 4-alpha-D-glucan maltohydrolase
Source: Hordeum vulgare
Molecular Weight: 58,300
Concentration: E-BARBL-20KU: Supplied at ~ 10,000 U/mL
E-BARBL-50KU: Supplied at ~ 10,000 U/mL.  
Expression: From barley flour
Specificity: Hydrolysis of α-1,4-D-glucosidic linkages in polysaccharides releasing maltose units from the non-reducing end.
Specific Activity: ~ 400 U/mg (40oC, pH 6.0 on soluble starch)
Unit Definition: One Unit of β-amylase activity is defined as the amount of enzyme required to release one µmole of maltose reducing-sugar equivalents per minute from soluble starch (10 mg/mL) in sodium phosphate buffer (200 mM), pH 6.0 at 40oC.
Temperature Optima: 60oC
pH Optima: 6
Application examples: For use in AACC and ASBC α-amylase assay procedures.
Method recognition: EBC Method 4.13 and ASBC Method Malt 7

The E-BARBL-20KU pack size has been discontinued (read more).

Pure, crystalline suspenson. Suitable for starch structural work.

Powder enzyme form (2000°L) is for use in AACC and ASBC α-amylase assay procedures (see E-BARBP).

Data booklets for each pack size are located in the Documents tab.

See our full range of β-amylase Carbohydrate Active enZYme products.

Megazyme publication
Measurement of β-amylase in cereal flours and commercial enzyme preparations.

McCleary, B. V. & Codd, R. (1989). Journal of Cereal Science, 9(1), 17-33.

A procedure previously developed for the assay of cereal-flour β-amylase has been improved and standardised. The improved procedure uses the substrate p-nitrophenyl maltopentaose (PNPG5) in the presence of near saturating levels of α-glucosidase. PNPG5 is rapidly hydrolysed by β-amylase but less readily by cereal α-amylases. The substrate is hydrolysed by β-amylase to maltose and p-nitrophenyl maltotriose (PNPG3). With the levels of α-glucosidase used in the substrate mixture, PNPG3 is rapidly cleaved to glucose and p-nitrophenol, whereas PNPG5 is resistant to hydrolysis by the α-glucosidase. The assay procedure has been standardised for several β-amylases and the exact degree of interference by cereal α-amylases determined. The procedure can be readily applied to the selective measurement of β-amylase activity in cereal and malted cereal-flours.

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Impact of Starch Binding Domain Fusion on Activities and Starch Product Structure of 4-α-Glucanotransferase.

Wang, Y., Wu, Y., Christensen, S. J., Janeček, Š., Bai, Y., Møller, M. S. & Svensson, B. (2023). Molecules, 28(3), 1320.

A broad range of enzymes are used to modify starch for various applications. Here, a thermophilic 4-α-glucanotransferase from Thermoproteus uzoniensis (TuαGT) is engineered by N-terminal fusion of the starch binding domains (SBDs) of carbohydrate binding module family 20 (CBM20) to enhance its affinity for granular starch. The SBDs are N-terminal tandem domains (SBDSt1 and SBDSt2) from Solanum tuberosum disproportionating enzyme 2 (StDPE2) and the C-terminal domain (SBDGA) of glucoamylase from Aspergillus niger (AnGA). In silico analysis of CBM20s revealed that SBDGA and copies one and two of GH77 DPE2s belong to well separated clusters in the evolutionary tree; the second copies being more closely related to non-CAZyme CBM20s. The activity of SBD-TuαGT fusions increased 1.2-2.4-fold on amylose and decreased 3–9 fold on maltotriose compared with TuαGT. The fusions showed similar disproportionation activity on gelatinised normal maize starch (NMS). Notably, hydrolytic activity was 1.3-1.7-fold elevated for the fusions leading to a reduced molecule weight and higher α-1,6/α-1,4-linkage ratio of the modified starch. Notably, SBDGA-TuαGT and-SBDSt2-TuαGT showed Kd of 0.7 and 1.5 mg/mL for waxy maize starch (WMS) granules, whereas TuαGT and SBDSt1-TuαGT had 3-5-fold lower affinity. SBDSt2 contributed more than SBDSt1 to activity, substrate binding, and the stability of TuαGT fusions.

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Inter-laboratory analysis of cereal beta-glucan extracts of nutritional importance: An evaluation of different methods for determining weight-average molecular weight and molecular weight distribution.

Ballance, S., Lu, Y., Zobel, H., Rieder, A., Knutsen, S. H., Dinu, V. T., et al. (2022). Food Hydrocolloids, 127, 107510.

In an interlaboratory study we compare different methods to determine the weight-average molecular weight (Mw) and molecular weight distribution of six cereal beta-glucan isolates of nutritional importance. Size-exclusion chromatography (SEC) with multi-angle light scattering (MALS), capillary viscometry, sedimentation velocity analytical ultracentrifugation and one asymmetric flow field-flow fractionation (AF4)-MALS method all yielded similar Mw values for mostly individual chains of dissolved beta-glucan molecules. SEC with post-column calcofluor detection underestimated the Mw of beta-glucan >500 × 103 g/mol. The beta-glucan molecules analysed by these methods were primarily in a random coil conformation as evidenced from individual Mark-Houwink-Kuhn-Sakurada (MHKS) scaling coefficients between 0.5 and 0.6 and Wales-Van Holde ratios between 1.4 and 1.7. In contrast, a second AF4-MALS method yielded much larger Mw values for these same samples indicating the presence and detection of beta-glucan aggregates. Storage of the six beta-glucan solutions in the dark at 4°C for 4 years revealed them to be stable. This suggests an absence of storage-induced irreversible aggregation phenomena or chain-scission. Shear forces in SEC and the viscometer capillary and hydrostatic pressure in analytical ultracentrifugation probably led to the reversable dissociation of beta-glucan aggregates into molecularly dissolved species. Thus, all these methods yield true weight-average molecular weight values not biased by the presence of aggregates as was the case in one of the AF4 based methods employed.

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Changes to fine structure, size and mechanical modulus of phytoglycogen nanoparticles subjected to high-shear extrusion.

Roman, L., Baylis, B., Klinger, K., de Jong, J., Dutcher, J. R. & Martinez, M. M. (2022). Carbohydrate Polymers, 298, 120080.

This study aims to enhance the understanding of the structure of maize phytoglycogen nanoparticles, and the effect of shear scission on their architecture, radius, stiffness, and deformability. Compared to amylopectin, phytoglycogen had a lower A:B chain ratio, a lower number of chains per B chain, and a much higher number of Afingerprint chains. Phytoglycogen (Mw = 28.0 × 106 g/mol) was subjected to high-shear extrusion with varying Specific Mechanical Energies (SMEs) using different screw speeds, showing a maximum stable molecular weight Mw of ~9.31 × 106 g/mol and a particle radius R reduction of 36 %, with a corresponding 20 % increase in the average mass density. Atomic force microscopy force spectroscopy revealed that nanoparticles extruded at the lowest SME (122 Wh/kg) exhibited a 20 % increase in Young's modulus. Higher SME values (up to 488 Wh/kg) resulted in an overall decrease in stiffness without further significant reductions in radius.

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On the role of the internal chain length distribution of amylopectins during retrogradation: double helix lateral aggregation and slow digestibility.

Roman, L., Yee, J., Hayes, A. M., Hamaker, B., Bertoft, E. & Martinez, M. M. (2020). Carbohydrate Polymers, 246, 116633.

A structure-digestion model is proposed to explain the formation of α-amylase-slowly digestible structures during amylopectin retrogradation. Maize and potato (normal and waxy) and banana starch (normal and purified amylopectin through alcohol precipitation), were analyzed for amylose ratio and size (HPSEC) and amylopectin unit- and internal-chain length distribution (HPAEC). Banana amylopectin (BA), like waxy potato (WP), exhibited a larger number of B3-chains, fewer BS- and Bfp-chains and lower S:L and BS:BL ratios than maize, categorizing BA structurally as type-4. WP exhibited a significantly greater tendency to form double helices (DSC and 13C-NMR) than BA, which was attributed to its higher internal chain length (ICL) and fewer DP6−12-chains. However, retrograded BA was remarkably more resistant to digestion than WP. Lower number of phosphorylated B-chains, more S- and Bfp-chains and shorter ICL, were suggested to result in α-amylase-slowly digestible structures through further lateral packing of double helices (suggested by thermo-rheology) in type-4 amylopectins.

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Comparison of molecular structure of oca (Oxalis tuberosa), potato, and maize starches.

Zhu, F. & Cui, R. (2019). Food Chemistry, 296, 116-122.

Oca (Oxalis tuberosa) is an underutilized species and represents a novel starch source. Composition and structure of starches from tubers of two commercial oca varieties grown in New Zealand were compared to those of normal maize and potato starches. The phosphorus content of oca starch was ∼60% of that of potato starch. The amylose content of oca starch (∼21%) was lower than that of maize and potato starches (concanavalin A precipitation method). The fine structure of oca amylopectin was much more similar to that of potato amylopectin than to that of maize amylopectin. Oca amylopectin had a shorter internal chain length and less fingerprint B-chains than potato amylopectin. The two oca starches were structurally and compositionally similar. Oca starch granules had a volume moment mean size of 34.5 μm and B-type polymorph. Comparative analysis suggested that oca starch has the potential to be developed as a novel starch source.

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Molecular structure of Maori potato starch.

Zhu, F. & Hao, C. (2018). Food Hydrocolloids, 80, 206-211.

New Zealand Maori potatoes (Taewa) represent unique genetic resources for potato quality, though they are much underutilized. In this report, the composition and molecular structure of starches from 5 Maori potato varieties were studied. In particular, the internal unit chain composition of the amylopectins in the form of β-limit dextrins were highlighted. Starches from a commercial modern potato variety and a maize variety with normal amylose contents were employed for comparison. Genetic diversity in the amylose (e.g., 22.6% in Moemoe to 28.6% in Turaekuri) and phosphorus (5.4 mg/100 g in Turaekuri to 7.0 mg/100 g in Kowiniwini) contents as well as the molecule structure of the starches (e.g., external chain length of amylopectin ranged from 13.0 glucosyl residues in Turaekuri to 15.8 glucosyl residues in Karuparera) has been revealed. Maori potato amylopectins have the highest amount of long unit and internal chains and the lowest amount of these chains among amylopectins from different sources. Overall, Maori potato starch appeared to be structurally and compositionally similar to modern potato starch.

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Photometric assay of maltose and maltose-forming enzyme activity by using 4-alpha-glucanotransferase (DPE2) from higher plants.

Smirnova, J., Fernie, A. R., Spahn, C. C. & Steup, M. (2017). Analytical Biochemistry, 532, 72-82.

Maltose frequently occurs as intermediate of the central carbon metabolism of prokaryotic and eukaryotic cells. Various mutants possess elevated maltose levels. Maltose exists as two anomers, (α- and β-form) which are rapidly interconverted without requiring enzyme-mediated catalysis. As maltose is often abundant together with other oligoglucans, selective quantification is essential. In this communication, we present a photometric maltose assay using 4-alpha-glucanotransferase (AtDPE2) from Arabidopsis thaliana. Under in vitro conditions, AtDPE2 utilizes maltose as glucosyl donor and glycogen as acceptor releasing the other hexosyl unit as free glucose which is photometrically quantified following enzymatic phosphorylation and oxidation. Under the conditions used, DPE2 does not noticeably react with other di- or oligosaccharides. Selectivity compares favorably with that of maltase frequently used in maltose assays. Reducing end interconversion of the two maltose anomers is in rapid equilibrium and, therefore, the novel assay measures total maltose contents. Furthermore, an AtDPE2-based continuous photometric assay is presented which allows to quantify β-amylase activity and was found to be superior to a conventional test. Finally, the AtDPE2-based maltose assay was used to quantify leaf maltose contents of both Arabidopsis wild type and AtDPE2-deficient plants throughout the light-dark cycle. These data are presented together with assimilatory starch levels.

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Small differences in amylopectin fine structure may explain large functional differences of starch.

Bertoft, E., Annor, G. A., Shen, X., Rumpagaporn, P., Seetharaman, K. & Hamaker, B. R. (2016). Carbohydrate Polymers, 140, 113-121.

Four amylose-free waxy rice starches were found to give rise to gels with clearly different morphology after storage for seven days at 4°C. The thermal and rheological properties of these gels were also different. This was remarkable in light of the subtle differences in the molecular structure of the amylopectin in the samples. Addition of iodine to the amylopectin samples suggested that not only external chains, but also the internal chains of amylopectin, could form helical inclusion complexes. It is suggested that these internal helical segments participate in the retrogradation of amylopectin, thereby stabilising the gels through double helical structures with external chains of adjacent molecules. Albeit few in number, such interactions appear to have important influences on starch functional properties.

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Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination.

Xia, H., Yandeau-Nelson, M., Thompson, D. B. & Guiltinan, M. J. (2011). BMC Plant Biology, 11(1), 95-107.

Background: Two distinct starch branching enzyme (SBE) isoforms predate the divergence of monocots and dicots and have been conserved in plants since then. This strongly suggests that both SBEI and SBEII provide unique selective advantages to plants. However, no phenotype for the SBEI mutation, sbe1a, had been previously observed. To explore this incongruity the objective of the present work was to characterize functional and molecular phenotypes of both sbe1a and wild-type (Wt) in the W64A maize inbred line. Results: Endosperm starch granules from the sbe1a mutant were more resistant to digestion by pancreatic α-amylase, and the sbe1a mutant starch had an altered branching pattern for amylopectin and amylose. When kernels were germinated, the sbe1a mutant was associated with shorter coleoptile length and higher residual starch content, suggesting that less efficient starch utilization may have impaired growth during germination. Conclusions: The present report documents for the first time a molecular phenotype due to the absence of SBEI, and suggests strongly that it is associated with altered physiological function of the starch in vivo. We believe that these results provide a plausible rationale for the conservation of SBEI in plants in both monocots and dicots, as greater seedling vigor would provide an important survival advantage when resources are limited.

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