The Architecture, Nature, and Mystery of Starch Granules. Part 2

Villwock, V. Kurtis; BeMiller, James N.

doi:10.1002/star.202100184

Cited by 5 publications

(7 citation statements)

References 205 publications

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“…Alpha-amylases can be divided into (i) maltogenic amylase, which produces maltose by cleaving the bonds at the nonreducing ends of amylose molecules, (ii) maltotriohydrolase, which cleaves the bonds at the nonreducing ends to produce maltotriose, (iii) maltotetrahydrolase, which cleaves the same bonds to produce maltotetraose, (iv) a-maltohexahydrolase, which produces maltohexaose, and so on. These variants differ from each other in the type of attack, which can be either random multichain or single-chain multiple [8]. Amylose is more readily hydrolyzed than amylopectin, and the ratio of the rate of hydrolysis of amylose to amylopectin can reach 2:1 [9].…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Mechanical Properties of Corn Starch Films for Sustainable Food Packaging by Optimizing Enzymatic Hydrolysis

et al. 2023

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The objective of this study was to investigate the effects of enzymatic hydrolysis using α-amylase from Bacillus amyloliquefaciens on the mechanical properties of starch-based films. The process parameters of enzymatic hydrolysis and the degree of hydrolysis (DH) were optimized using a Box–Behnken design (BBD) and response surface methodology (RSM). The mechanical properties of the resulting hydrolyzed corn starch films (tensile strain at break, tensile stress at break, and Young’s modulus) were evaluated. The results showed that the optimum DH for hydrolyzed corn starch films to achieve improved mechanical properties of the film-forming solutions was achieved at a corn starch to water ratio of 1:2.8, an enzyme to substrate ratio of 357 U/g, and an incubation temperature of 48 °C. Under the optimized conditions, the hydrolyzed corn starch film had a higher water absorption index of 2.32 ± 0.112% compared to the native corn starch film (control) of 0.81 ± 0.352%. The hydrolyzed corn starch films were more transparent than the control sample, with a light transmission of 78.5 ± 0.121% per mm. Fourier-transformed infrared spectroscopy (FTIR) analysis showed that the enzymatically hydrolyzed corn starch films had a more compact and solid structure in terms of molecular bonds, and the contact angle was also higher, at 79.21 ± 0.171° for this sample. The control sample had a higher melting point than the hydrolyzed corn starch film, as indicated by the significant difference in the temperature of the first endothermic event between the two films. The atomic force microscopy (AFM) characterization of the hydrolyzed corn starch film showed intermediate surface roughness. A comparison of the data from the two samples showed that the hydrolyzed corn starch film had better mechanical properties than the control sample, with a greater change in the storage modulus over a wider temperature range and higher values for the loss modulus and tan delta, indicating that the hydrolyzed corn starch film had better energy dissipation properties, as shown by thermal analysis. The improved mechanical properties of the resulting film of hydrolyzed corn starch were attributed to the enzymatic hydrolysis process, which breaks the starch molecules into smaller units, resulting in increased chain flexibility, improved film-forming ability, and stronger intermolecular bonds.

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Section: Introductionmentioning

confidence: 99%

Enhancing the Mechanical Properties of Corn Starch Films for Sustainable Food Packaging by Optimizing Enzymatic Hydrolysis

et al. 2023

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“…In response to these concerns, biopolymers are emerging as promising substitutes, primarily sourced from renewable raw materials and often exhibiting biodegradable properties [3][4][5]. Starch, an abundantly available natural resource, serves as a cost-effective renewable raw material for biopolymer production [6][7][8][9][10]. The conversion of starch into a thermoplastic polymer, known as thermoplastic starch (TPS), is facilitated through the incorporation of plasticizers [11,12].…”

Section: Introductionmentioning

confidence: 99%

Solid-State Luminescence with a Large Stokes Shift in Starch Functionalized with Low-Content ESIPT Dye

Colonetti,

da Luz,

Rodembusch

2024

Colorants

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Herein, we present the preparation of solid-state photoactive starches with a large Stokes shift, along with the resulting materials. In this investigation, 2-(2′-hydroxyphenyl)benzazole derivatives responsive to intramolecular proton transfer in the excited state (ESIPT) were covalently bonded to the polymeric structure of starch through a reaction involving an isothiocyanate group and the hydroxyl groups of starch. These compounds exhibit absorption at approximately 350 nm, which is related to fully spin- and symmetry-allowed π → π* electronic transitions, and solid-state fluorescence at approximately 500 nm, which features a significant separation between the absorption and emission maxima (~9000 cm−1). Due to the minimal use of fluorophores in functionalized starch preparation, this modification does not affect the original properties of the starch. Finally, photoactive starch-based films with significantly high transparency were successfully produced.

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“…However, the tertiary structures of glycogen and starch are distinct, with glycogen molecules existing as highly branched clusters that have a glycogenin protein molecule at their center. Starch, on the other hand, has a more complex structure that consists of two distinct types of molecules: amylose, which has very few branches (two to four chains per 1000 glucose units [2,3]), and amylopectin, which is substantially more branched (two to four branches per 100 linear glucose units). Together, these molecules make up a starch granule consisting of alternating layers of amorphous and semi-crystalline material [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…Starch, on the other hand, has a more complex structure that consists of two distinct types of molecules: amylose, which has very few branches (two to four chains per 1000 glucose units [2,3]), and amylopectin, which is substantially more branched (two to four branches per 100 linear glucose units). Together, these molecules make up a starch granule consisting of alternating layers of amorphous and semi-crystalline material [2,3]. These basic structures can differ markedly depending on the organism and, in the case of starch, tissue type.…”

Section: Introductionmentioning

confidence: 99%

“…The biosynthetic pathways of glycogen and starch are very similar and involve three enzymes to make the parent glycan and a variety of enzymes that are involved in tailoring the basic material, with debranching enzymes to remove incorrectly placed branches and kinases that phosphorylate glucose units being the most common activities [1,3,7,8]. The three enzymes common to all storage polysaccharide synthesis are first an NDP-glucose pyrophosphorylase (ADP-glucose pyrophosphorylase in bacteria and plants and UDPglucose pyrophosphorylase in other eukaryotes) [9,10], which synthesizes an activated NDP-glucose unit from either ATP or UTP and glucose-1-phosphate [10,11].…”

Section: Introductionmentioning

confidence: 99%

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The Structure of Maltooctaose-Bound Escherichia coli Branching Enzyme Suggests a Mechanism for Donor Chain Specificity

Fawaz,

Bingham,

Nayebi

et al. 2023

Molecules

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Glycogen is the primary storage polysaccharide in bacteria and animals. It is a glucose polymer linked by α-1,4 glucose linkages and branched via α-1,6-linkages, with the latter reaction catalyzed by branching enzymes. Both the length and dispensation of these branches are critical in defining the structure, density, and relative bioavailability of the storage polysaccharide. Key to this is the specificity of branching enzymes because they define branch length. Herein, we report the crystal structure of the maltooctaose-bound branching enzyme from the enterobacteria E. coli. The structure identifies three new malto-oligosaccharide binding sites and confirms oligosaccharide binding in seven others, bringing the total number of oligosaccharide binding sites to twelve. In addition, the structure shows distinctly different binding in previously identified site I, with a substantially longer glucan chain ordered in the binding site. Using the donor oligosaccharide chain-bound Cyanothece branching enzyme structure as a guide, binding site I was identified as the likely binding surface for the extended donor chains that the E. coli branching enzyme is known to transfer. Furthermore, the structure suggests that analogous loops in branching enzymes from a diversity of organisms are responsible for branch chain length specificity. Together, these results suggest a possible mechanism for transfer chain specificity involving some of these surface binding sites.

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The Architecture, Nature, and Mystery of Starch Granules. Part 2

Cited by 5 publications

References 205 publications

Enhancing the Mechanical Properties of Corn Starch Films for Sustainable Food Packaging by Optimizing Enzymatic Hydrolysis

Enhancing the Mechanical Properties of Corn Starch Films for Sustainable Food Packaging by Optimizing Enzymatic Hydrolysis

Solid-State Luminescence with a Large Stokes Shift in Starch Functionalized with Low-Content ESIPT Dye

The Structure of Maltooctaose-Bound Escherichia coli Branching Enzyme Suggests a Mechanism for Donor Chain Specificity

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