Content: | 600 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: | Isoamylase |
EC Number: | 3.2.1.68 |
CAZy Family: | GH13 |
CAS Number: | 9067-73-6 |
Synonyms: | isoamylase; glycogen 6-alpha-D-glucanohydrolase |
Source: | Pseudomonas sp. |
Molecular Weight: | 71,500 |
Concentration: | Supplied at ~ 200 U/mL |
Expression: | Purified from Pseudomonas sp. |
Specificity: | Hydrolysis of (1,6)-α-D-glucosidic branch linkages in glycogen, amylopectin and their β-limit dextrins. |
Specific Activity: | ~ 120 U/mg (40oC, pH 4.0 on oyster glycogen) (equivalent to 16 MU Sigma Units/mg) |
Unit Definition: | One unit of isoamylase activity is the amount of enzyme required to release one µmole of D-glucose reducing sugar equivalent in the presence of oyster glycogen per min at pH 4.0 and 40oC. |
Temperature Optima: | 50oC |
pH Optima: | 4 |
Application examples: | Applications in carbohydrate research and in the food and feeds, and cereals industry. |
Method recognition: | AOAC Method 2000.11 and GB Standard 5009.245-2016 |
Pure Isoamylase (Glycogen 6-glucanohydrolase) for use in biochemical enzyme assays and in vitro diagnostic analysis. Isoamylase, Fructanase (E-FRMXPD) and Amyloglucosidase (E-AMGDF) are used in the enzyme hydrolysis step of two validated methods for the determination of polydextrose (a low molar mass dietary fiber) in foods: AOAC method 2000.11 and Chinese GB Standard 5009.245-2016.
Please refer to E-ISAMYHP for high purity enzyme suitable for use in starch structural research.
We have a wide range of other CAZyme products available.
Validation of Methods
Response of texture, rheological characteristics and starch molecular structure of super hybrid indica rice to different nitrogen fertilizer levels.
Yang, X., Liu, L., Mahmood, N., Qin, J., Zhao, Q. & Song, X. (2025). Carbohydrate Polymers, 336, 123927.
The application of nitrogen (N) fertilizer increases rice yield while potentially leading to a decline in quality, but the intrinsic mechanism remains unclear. Herein, the effects of varying N levels (0, 200, 260 and 400 kg N ha−1) on the texture, rheological characteristics and starch molecular structure of four super hybrid indica rice cultivars with different yield potentials were investigated. When N levels increased from 0 to 400 kg N ha−1, the apparent amylose content (ACC) decreased by 10.68%-27.38%, while protein contents increased by 10.11%-43.98%. The mechanical strength of the grains weakened, but the hardness of the cooked rice increased. Furthermore, pasting viscosity decreased, whereas the storage modulus (G') increased. Appropriate N level at 200 kg N ha−1 reduced the proportion of fa (DP 6-12) chains while elevated fb2 (DP13-24) and fb3 (DP ≥ 37) chains, resulting in more ordered structures and higher gelatinization temperature. Conversely, high N at 400 kg N ha−1 led to an accumulation of protein particles in the endosperm, hindering starch granule development, which increased short chains and reduced rice quality. The response of starch molecular structures to N levels varied among the four super hybrid rice cultivars, although the overall trend remained consistent.
Hide AbstractEnhanced co-production of extracellular biopolymers and intracellular lipids by Rhodotorula using lignocellulose hydrolysate and fish oil by-product urea.
Byrtusová, D., Zimmermann, B., Kohler, A. & Shapaval, V. (2025). Biotechnology for Biofuels and Bioproducts, 18(1), 1-19.
Background: A key objective in microbial biorefinery technologies is to identify resilient microorganisms capable of simultaneously synthesizing diverse bioactive metabolites. Among these, Rhodotorula yeasts emerge as promising candidates for converting various waste streams and by-products into high-value chemicals. Their industrial potential stems from their ability to accumulate significant amounts of lipids and carotenoids while also secreting extracellular polymers such as exopolysaccharides, polyol esters of fatty acids, glycolipids, and enzymes—many of which remain to be fully characterized. Results: Among the five Rhodotorula strains tested, three exhibited substantial exopolysaccharide production. Notably, Rhodotorula graminis CCY 20-2-47 strain was identified, for the first time, to produce two distinct extracellular biopolymers—exopolysaccharides or polyol esters of fatty acids—depending on the growth conditions. It was observed enhanced production of exopolysaccharides up to 7.2 g L−1 and 14.7 g L−1 lipid-rich biomass by Rhodotorula graminis CCY 20-2-47 using lignocellulose hydrolysate and urea by-product. This study, for the first time, reports triggering effect of Mn2+ on exopolysaccharide production in Rhodotorula. Glucose-based medium resulted in co-production of polyol esters of fatty acids (3.9 g L−1) and lipid-rich biomass (15 g L−1) for Rhodotorula graminis CCY 20-2-47. Batch bioreactor fermentation for Rhodotorula graminis CCY 20-2-47 resulted in production of 13.1 g L−1 of exopolysaccharides and 50% w/w intracellular lipids when using lignocellulose hydrolysate and urea by-product. In contrast, 7.4 g L−1 of polyol esters of fatty acids and 35% w/w intracellular lipids were produced by the same strain on medium with pure glucose. Conclusions: In conclusion, Rhodotorula yeasts demonstrate significant potential for microbial biorefineries due to their ability to efficiently convert diverse waste substrates into valuable biomaterials, including lipids and extracellular biopolymers. This study provides new insights into a potential metabolic switch in extracellular polymer biosynthesis, driven by Mn2+ availability in the culture medium.
Hide AbstractAccounting for shear scission in the size-exclusion chromatography of debranched starch.
Zhu, J., Wang, Z. & Gilbert, R. G. (2025). Analytical and Bioanalytical Chemistry, 1-13.
The chain-length distribution (CLD) of starch influences many functional properties of starch-containing substances, and also contains information about starch biosynthetic processes. The commonest method for measuring this CLD is to debranch the starch enzymatically, and then to measure the molecular weight distribution of the resulting linear chains using size-exclusion chromatography (SEC). However, SEC suffers from various artifacts, including shear scission of longer chains. Here, a method of correcting for such shear scission is developed: fitting the apparent CLDs (affected by shear scission) with biosynthesis-based models, over a range of flow rates, and extrapolating the resulting model-based parameters to zero flow rate. To apply this, the apparent CLDs of five rice starches were measured using SEC with a range of flow rates, and these apparent CLDs were parameterized using biosynthesis-based models. The model parameters fitted from CLDs at different flow rates were extrapolated to zero flow rate, and were then used to calculate the CLD that would be obtained with zero flow rate, thereby taking partial account of shear scission. The extrapolation suggests that shear scission significantly degrades extra-long (degree of polymerization, DP, >1500) amylose chains to shorter chains (DP ~ 500–1500), which, if uncorrected, would vitiate inferences from SEC results. The partial correction method devised here can be used to develop more reliable relationships between structural and biosynthesis-related parameters of starch and functional properties of starch-containing substances.
Hide AbstractFermentative in situ synthesis of isomalto/malto-polysaccharides in sourdough.
Brand, N., Stadler, F. M., Hahn, L., Borisova, Z. & Wefers, D. (2025). Food Chemistry, 488, 144846.
Some sourdough-derived lactic acid bacteria were shown to fermentatively synthesize potentially prebiotic isomalto/malto-polysaccharides (IMMPs) from maltodextrins. Therefore, the application of suitable starter cultures and adjusted fermentation conditions could be used to achieve a fermentative synthesis of IMMPs in sourdough, however, this has not been investigated yet. To monitor in situ IMMP synthesis, a new method based on endo-dextranase hydrolysis and quantification of released isomaltose was developed. Subsequently, it was applied to determine the amount of dextran equivalents (fermentatively formed α-1,6-linkages) in sourdoughs produced under different conditions. Of all seven investigated strains, Limosilactobacillus reuteri TMW 1.106 in combination with the addition of pregelatinized starch and starch-debranching enzymes produced by far the highest amount of IMMPs within 20 h of fermentation. Other changes in fermentation conditions did not significantly increase IMMP formation. However, applying adjusted conditions during sourdough fermentation may be used to increase the amount of potentially prebiotic carbohydrates in bread.
Hide AbstractTowards a better understanding of the structure-function relationship of chestnut starches.
Li, S., Chao, C., Yu, J., Copeland, L., Yang, Y. & Wang, S. (2025). International Journal of Biological Macromolecules, 311, 143702.
Chestnut starch is of increasing interest for applications in foods but has been studied to a much lesser extent than other food starches. Hence, the structure-function relationships of starches isolated from eight chestnut cultivars were examined. The starch granules were round, oval and conical in shape, with average particle size and amylose content ranging between 7.14 and 9.39 μm and 29.9 to 34.0 %, respectively. Chain length distributions showed larger differences between the starches in the A chains than in the B1 ∼ B3 chains. All chestnut starches exhibited a typical B-type crystalline pattern, with the relative crystallinity ranging from 34.1 to 40.6 %. Significant differences were also observed in short-range molecular order and in functional properties. Pearson correlation analyses showed that amylose content was positively correlated with peak and breakdown viscosities and negatively correlated with the rate of in vitro digestion of the starches. The short A chains were negatively and the B2 or B3 chains positively correlated with the peak and breakdown viscosities, but the opposite correlations were noted for the rate of in vitro digestion of the starches. This study contributes new insights into an understanding the structure-function relationships of chestnut starches and for their applications in foods.
Hide AbstractInfluence of debranched maize starch on pullulan/gelatin nanofibers loaded with debranched starch-tannin complexes.
Liang, Q., Yang, Y., Kilmartin, P. A. & Gao, Q. (2025). Carbohydrate Polymers, 361, 123630.
Grape seed tannins, the by-products of wine-making, are rich in antioxidant activity due to their high phenolic content. In this study, tannin was complexed with debranched starch from three types of maize starch (high amylose maize starch, normal maize starch and waxy maize starch). The starch-tannin complexes were further incorporated into pullulan/gelatin nanofibers to obtain an antioxidant composite nanofibrous film. The characteristics of debranched starch-tannin complexes were examined for incorporation into nanofibers. As a result, the long-chain amylose-tannin complexes exhibited V-type and B-type crystalline structure, while the short-chain amylose-tannin complexes showed exclusively B-type crystalline structure. After encapsulation, nanofibers loaded with long-chain amylose-tannin complexes demonstrated significantly higher tannin loading capacity (2.54 ± 0.06 %), slower tannin release (18.2 %) and better mechanical properties, with Young's modulus of 233.7 ± 36.3 MPa, elongation at break of 15.4 ± 0.6 % and tensile strength of 18.2 ± 0.9 MPa, compared to those loaded with short-chain amylose-tannin complexes. This study provided an understanding of how de-branched starches influenced the potential of starch-tannin complexes for use in antioxidant food packaging through electrospinning.
Hide AbstractOsGATA7 and SMOS1 cooperatively determine rice taste quality by repressing OsGluA2 expression and protein biosynthesis.
Cao, N., Zhou, W., Zhao, F., Jiao, G., Xie, L., Lu, A., Wu, J., Zhu, M., Liu, Y., Yu, J., Zhao, R., Yang, X., Hu, S., Sheng, Z., Wei, X., Lv, Y., Tang, S., Shao, G. & Hu, P. (2025). Nature Communications, 16(1), 3513.
Taste is crucial for the economic value of rice (Oryza sativa L.) and determines consumer preference. However, the mechanisms underlying taste formation have remained unclear. Here, we show that OsGATA7 contributes to desirable taste quality by affecting the swelling properties, texture, and taste value of cooked rice. OsGATA7 binds to the promoter of SMOS1, and activates its expression, thereby regulating taste quality. Furthermore, SMOS1 binds to the promoter of the protein biosynthesis gene OsGluA2, and recruits the PRC2 complex to repress its expression, leading to increased protein content. The overexpression of both OsGATA7 and SMOS1 reduces protein content and enhances taste quality. The haplotypes OsGATA7Hap1 and SMOS1Hap1 maintain low protein content and improve taste scores. Collectively, these findings reveal a regulatory mechanism for taste quality formation mediated by the OsGATA7–SMOS1 protein content module, and identify the elite haplotypes OsGATA7Hap1 and SMOS1Hap1 as a means to improve taste quality.
Hide AbstractCreating a Superior Wx Allele with Temperature-Responsive Amylose Regulation and a Novel Transcriptional Pattern in Rice via CRISPR/Cas9-Mediated Promoter Editing.
Yan, J., Yu, J., Shen, H., Zhou, L., Chen, Z., Fan, X., Li, Q., Zhang, C., Liu, Q., Huang, L., & Liu, Q. (2025). Foods, 14(8), 1330.
High quality stands as a pivotal competitive edge in the rice industry. Optimizing amylose content (AC) and the physicochemical properties of endosperm starch by regulating the Wx gene is crucial for enhancing rice grain quality. In this study, we created a novel Wxb-d25 allele by deleting a 25 bp segment (−26 to −2) within the Wx core promoter using CRISPR/Cas9. Compared with the wild type and the previously reported Wxb-i1, Wxb-d25 exhibited no significant changes in agronomic traits. However, its grains displayed temperature-dependent variations in AC and altered transparency and viscosity characteristics, holding the potential to synergistically improve both the eating and cooking quality (ECQ) and appearance quality (AQ) of rice. Further studies demonstrated that this promoter modification, by partially disrupting the transcription initiator, significantly downregulated the original Wx-01 transcript and generated a novel Wx transcript (ONT.7395.1) in Wxb-d25 grains. Despite its low expression abundance, the ONT.7395.1 transcript could be completely processed into mature Wx mRNA. The combined effects of the dual transcripts resulted in significantly increased Wx gene expression and AC in Wxb-d25 grains under conventional cultivation conditions. These findings provide a genetic resource and a theoretical foundation for utilizing the Wxb-d25 allele to improve rice grain quality.
Hide AbstractThermal and structural characteristics of novel V-type starch nanoparticles synthesized via the H2O2/UV synergistic recrystallization approach.
Wang, S., Wu, C., Fan, G., Li, T., Zhou, D. & Li, X. (2025). Innovative Food Science & Emerging Technologies, 102, 104000.
Unlike the traditional nanoprecipitation method, this study introduced a novel methodology for fabricating V-type starch nanoparticles. The short-chain starch, derived from a synergistic treatment involving H₂O₂ and UV light, was recrystallized to synthesize a novel class of V-type chestnut starch nanoparticles. Furthermore, the study explored the influence of varying pH conditions on the efficacy of the H2O2 and UV treatment, as well as their subsequent effects on properties of the starch nanoparticles. The results showed that H₂O₂ and UV treatment effectively degrade starch into short chains (DP < 37), with pH significantly influencing chain fragmentation and oxidation. With the exception of when the pH was 11, starch chains (13 < DP < 24) accounted for over 60%. However, when the pH was 11, the proportion of starch chains (DP < 5) increased sharply to 36.12%. At a pH of 7, the highest carboxyl content (6.65 COOH/100GU) was observed. Starch nanoparticles synthesized from short-chain starch exhibited uniform spherical morphology, and at a pH of 5, these particles achieved the smallest and most uniform size (50-70 nm). FTIR results indicated that the hydrogen bonding between short-chain starch molecules was enhanced after treatment. X-ray diffraction analysis revealed that the starch nanoparticles possessed a V-type crystalline structure. These nanoparticles displayed excellent thermal stability, with peak gelatinization temperatures above 100°C. Notably, the peak gelatinization temperature reaches 119.83°C at a pH of 5, highlighting their superior thermal properties as bio-based macromolecular materials. This study offered valuable insights into oxidized starch nanoparticle preparation and nano-carrier development.
Hide AbstractHydrothermal treatment of recrystallized linear α-glucans targeting the preparation of starch nanocrystals with high yields and thermostability.
Wang, R., Wang, M., Zhou, X., Luo, X., Li, Y., Ren, J., Li, D. & Zhang, H. (2025). Food Hydrocolloids, 163, 111069.
Starch nanocrystals (SNCs) derived from native starches had low yields and limited thermostability. This study aimed to produce SNCs with high yields and improved thermostability using recrystallized linear α-glucans (LGs) as substrates. Herein, waxy rice starch (WRS) was sequentially modified by amylosucrase and pullulanase to produce LGs with controllable length. The recrystallization of LGs exhibited typical B-type patterns, and a longer length of LGs led to higher relative crystallinity. Moreover, the further hydrothermal treatment of LGs (HLGs) remarkably enhanced their crystalline structure. Compared to native WRS, LGs and HLGs showed a much greater thermostability and higher resistance to acidic hydrolysis. Accordingly, the yield of SNCs derived from LGs (LGs@SNCs) and HLGs (HLGs@SNCs) reached as much as 40.21% and 46.99% at 120 h, respectively, which was almost 10 times higher than the native WRS derived SNCs (WRS@SNCs). The LGs@SNCs and HLGs@SNCs showed a dimension of 413.98-780.76 nm, and a long chain length of HLGs@SNCs endowed them with high thermostability, e.g., the peak gelatinization temperature of HLGs@SNCs exceeded 130 °C. The findings of the present study may provide an efficient technology to produce SNCs with high yields and improved thermostability enabling novel applications.
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