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β-Amylase (Barley)

Product code: E-BARBL-50KU



50,000 Units

Prices exclude VAT

Available for shipping

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: > 4 years at 4oC
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.

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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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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Debranching of β-dextrins to explore branching patterns of amylopectins from three maize genotypes.

Xia, H. & Thompson, D. B. (2006). Cereal Chemistry, 83(6), 668-676.

The amylopectin (AP) branching pattern is a fundamental feature of AP fine structure but a little-studied one. In this work, we followed enzyme digestion over time for AP from three maize genotypes (wx, du wx, and AP of ae VII). The objective was to describe differences in the progress of β-amylolysis and in subsequent debranching of β-limit dextrins (β-LD). During the progress of β-amylolysis, changes in the distribution of short residual chains show that the enzyme favors hydrolysis farthest from branch points. On treating β-LD with isoamylase (IA) alone, debranching was incomplete. Using IA and pullulanase (PUL) sequentially, a similar increase in the DP 5–7 region and the peak at DP 6 were observed for all samples, indicating a common element in the branching pattern. This similarity suggests that, despite differences in the proportion of short to long B chains, the most closely associated branch points may be arranged in a similar way for these AP. We suggest that the increase in DP 6 after PUL digestion would result from debranching of linear DP 6 residual B chains that originally had two branch points, consistent with interior segment length (ISL) of 1 or 2.

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