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Plant Molecular Biology Mar 2022Two opposing models for the amylopectin structure are historically and comprehensively reviewed, which leads us to a better understanding of the specific fine structure... (Review)
Review
Two opposing models for the amylopectin structure are historically and comprehensively reviewed, which leads us to a better understanding of the specific fine structure of amylopectin. Amylopectin is a highly branched glucan which accounts for approximately 65-85 of starch in most plant tissues. However, its fine structure is still not fully understood due to the limitations of current methodologies. Since the 1940 s, many scientists have attempted to elucidate the distinct structure of amylopectin. One of the most accepted concepts is that amylopectin has a structural element known as "cluster", in which neighboring side chains with a degree of polymerization of ≥ 10 in the region of their non-branched segments form double helices. The double helical structures are arranged in inter- and intra-clusters and are the origin of the distinct physicochemical and crystalline properties of starch granules. Several models of the cluster structure have been proposed by starch scientists worldwide during the progress of analytical methods, whereas no direct evidence so far has been provided. Recently, Bertoft and colleagues proposed a new model designated as "the building block and backbone (BB) model". The BB model sharply contrasts with the cluster model in that the structural element for the BB model is the building block, and that long chains are separately synthesized and positioned from short chains constituting the building block. In the present paper, we conduct the historical review of the cluster concept detailing how and when the concept was established based on experimental results by many scientists. Then, differences between the two opposing concepts are explained and both models are critically discussed, particularly from the point of view of the biochemical regulation of amylopectin biosynthesis.
Topics: Amylopectin; Carbohydrate Conformation; Isoenzymes; Models, Molecular
PubMed: 34599732
DOI: 10.1007/s11103-021-01183-3 -
Plant Molecular Biology Jul 2023Amylopectin is a highly branched glucan which accounts for approximately 65-85% of starch in most plant tissues. It is crucially important to understand the biosynthetic... (Review)
Review
Amylopectin is a highly branched glucan which accounts for approximately 65-85% of starch in most plant tissues. It is crucially important to understand the biosynthetic process of this glucan in regulating the structure and functional properties of starch granules. Currently, the most accepted ideas of structural feature and biosynthesis of amylopectin are that amylopectin is composed of a branched element called "cluster" and that the essential process of amylopectin biosynthesis is to reproduce a new cluster from the existing cluster. The present paper proposes a model explaining the whole process of amylopectin biosynthesis as to how the new cluster is reproduced by concerted actions of multiple isoforms of starch biosynthetic enzymes, particularly by combinations of distinct roles of starch branching enzyme (BE) isoforms. This model proposes for the first time the molecular mechanism as to how the formation of a new cluster is initiated, and the reason why BEI can play a major role in this step. This is because BEI has a rather broad chain-length preference compared to BEIIb, because a low preference of BEI for the substrate chain-length is advantageous for branching a couple of elongated chains that are not synchronously formed and thus these chains having varied lengths could be safely attacked by this isoform. On the contrary, it is unlikely that BEIIb is involved in this reaction because it can react to only short chains having degree of polymerization of 12-14. BEIIa is possibly able to complement the role of BEI to some extent, because BEIIa can attack basically short chains but its chain-length preference is lower compared with BEIIb. The model implies that the first branches mainly formed by BEI to construct the amorphous lamellae whereas the second branches predominantly formed by BEIIb are located mainly in the crystalline lamellae. This paper provides new insights into the roles of BEI, BEIIb, and BEIIa in amylopectin biosynthesis in cereal endosperm.
Topics: Amylopectin; 1,4-alpha-Glucan Branching Enzyme; Isoenzymes; Starch; Glucans; Reproduction; Oryza
PubMed: 37294528
DOI: 10.1007/s11103-023-01352-6 -
Journal of Materials Chemistry. B Jan 2021Self-adhesiveness is highly desirable for conformal and seamless wearable electronics. Here, a starch-tackifying method is proposed to obtain adhesive and robust...
Self-adhesiveness is highly desirable for conformal and seamless wearable electronics. Here, a starch-tackifying method is proposed to obtain adhesive and robust hydrogel conductors with the assistance of amylopectin (Amy). The conductive hydrogels are composed of Amy/poly(acrylamide-acrylic acid) polymer networks, which can be assembled into wearable sensors. The hydrogels rely on physical interactions such as hydrogen bonding that can be generated on the surface of the material, including skin, to exhibit robust and repeatable self-adhesive behaviors. Besides, the construction of a covalent and dynamic dual cross-linking network endows the hydrogel with good mechanical properties to bear repeated stretching and flexible deformation. In particular, the hydrogel is assembled into a wearable stretchable and compressible sensor and exhibits a repeatable and stable resistance signal variation for detecting both large and tiny scale human activities and physiological signals, such as bending of joints, speaking, walking, and jumping. Accordingly, the amylopectin-enabled skin-mounted hydrogel sensor can be considered as an ideal choice for human movement monitoring and personal health diagnosis.
Topics: Amylopectin; Biocompatible Materials; Humans; Hydrogels; Materials Testing; Molecular Structure; Monitoring, Physiologic; Particle Size; Skin; Surface Properties; Wearable Electronic Devices
PubMed: 33415324
DOI: 10.1039/d0tb02460k -
Critical Reviews in Food Science and... 2015Acid hydrolysis is an important chemical modification that can significantly change the structural and functional properties of starch without disrupting its granular... (Review)
Review
Acid hydrolysis is an important chemical modification that can significantly change the structural and functional properties of starch without disrupting its granular morphology. A deep understanding of the effect of acid hydrolysis on starch structure and functionality is of great importance for starch scientific research and its industrial applications. During acid hydrolysis, amorphous regions are hydrolyzed preferentially, which enhances the crystallinity and double helical content of acid hydrolyzed starch. This review discusses current understanding of the effect of acid hydrolysis on starch structure and functionality. The effects of acid hydrolysis on amylose content, chain length distribution of amylopectin molecules, molecular and crystalline organization (including lamellar structure) and granular morphology are considered. Functional properties discussed include swelling power, gelatinization, retrogradation, pasting, gel texture, and in vitro enzyme digestibility. The paper also highlights some promising applications of acid hydrolyzed starch (starch nanocrystals) in the preparation of biodegradable nanocomposites, bio-hydrogen, and slowly digestible starch-based healthy foods.
Topics: Acids; Amylopectin; Amylose; Carbohydrate Conformation; Chemical Phenomena; Crystallization; Digestion; Hydrolysis; Molecular Structure; Nanocomposites; Starch; Structure-Activity Relationship
PubMed: 24915341
DOI: 10.1080/10408398.2012.684551 -
Carbohydrate Polymers Nov 2022The role of amylose content in electrospinning starch nanofibres is well understood, but that is not the case for the roles of the molecular structures of amylose and...
The role of amylose content in electrospinning starch nanofibres is well understood, but that is not the case for the roles of the molecular structures of amylose and amylopectin. Here, correlations between starch molecular-structure parameters and electrospinnability evaluation indices (average droplet number, average bead number, and average fibre diameter) and dope properties (shear viscosity, conductivity, and surface tension) were examined. Starches with lower amounts of short amylopectin chains, higher amounts of either/or long amylopectin chains and/or lower degree of branching showed decreased viscosity of the electrospinning dopes, and resulted in a reduced average droplet number of electrospun fibre mats. The molecular sizes of amylose and whole starch, and the average degree of polymerization for amylose chains, all correlated with the shear viscosity and surface tension of dopes, and thus influenced the average fibre diameter. This expands the current understanding between amylopectin molecular structure and starch electrospinning, thereby assisting a better choice of starches for desired electrospinnability properties.
Topics: Amylopectin; Amylose; Carbohydrates; Dietary Fiber; Molecular Structure; Starch; Viscosity
PubMed: 36088001
DOI: 10.1016/j.carbpol.2022.119959 -
Cell Aug 1996
Review
Topics: Amylopectin; Carbohydrate Conformation; Glucans; Glycogen; Models, Molecular; Starch
PubMed: 8756717
DOI: 10.1016/s0092-8674(00)80107-5 -
Nature Dec 1947
Topics: Amylopectin
PubMed: 18917308
DOI: 10.1038/160900a0 -
International Journal of Biological... Dec 2020Annealing behavior of amylose and amylopectin was unclear. In this work, high purity amylose and amylopectin were extracted from rice starch, and structural properties...
Annealing behavior of amylose and amylopectin was unclear. In this work, high purity amylose and amylopectin were extracted from rice starch, and structural properties of the retrograded rice starch, amylose, and amylopectin before and after annealing treatment were explored. It was found that the purity of the amylose and amylopectin was 95.64% ± 2.69% and 94.98% ± 0.97%, respectively. Their molecular weight was (2.93 ± 0.21) × 10 Da and (5.90 ± 0.13) × 10 Da, respectively. Besides, the relative crystallinities and ratios of 1047 cm/1022 cm of the retrograded rice starch and amylose were significantly increased by annealing treatment, while that of retrograded amylopectin did not change. These results clarified that amylose was more sensitive to annealing treatment than amylopectin, and amylose was more responsible for annealing of starch than amylopectin. The findings contributed to a better understanding of the annealing behavior of starch.
Topics: Amylopectin; Amylose; Chemical Fractionation; Chemical Phenomena; Molecular Weight; Oryza; Spectrum Analysis; Starch
PubMed: 32890568
DOI: 10.1016/j.ijbiomac.2020.08.245 -
Carbohydrate Polymers May 2017Structure-function relationships of starch components remain a subject of research interest. Quinoa starch has very small granules (∼2μm) with unique properties. In...
Structure-function relationships of starch components remain a subject of research interest. Quinoa starch has very small granules (∼2μm) with unique properties. In this study, nine quinoa starches varied greatly in composition, structure, and physicochemical properties were selected for the analysis of structure-function relationships. Pearson correlation analysis revealed that the properties related to gelatinization such as swelling power, water solubility index, crystallinity, pasting, and thermal properties are much affected by the amylopectin chain profile and amylose content. The parameters of gel texture and amylose leaching are much related to amylopectin internal structure. Other properties such as enzyme susceptibility and particle size distribution are also strongly correlated with starch composition and amylopectin structure. Interesting findings indicate the importance of amylopectin internal structure and individual unit chain profile in determining the physicochemical properties of starch. This work highlights some relationships among composition, amylopectin structure and physicochemical properties of quinoa starch.
Topics: Amylopectin; Amylose; Chenopodium quinoa; Molecular Structure; Starch
PubMed: 28325341
DOI: 10.1016/j.carbpol.2017.02.014 -
Carbohydrate Polymers Feb 2017Starch granule size, shape and structure of amylopectin are species specific and influence starch properties and end-use of starch. Amylopectin glucan chain structure...
Starch granule size, shape and structure of amylopectin are species specific and influence starch properties and end-use of starch. Amylopectin glucan chain structure was used to predict the starch botanical sources. Mathematical probability for accumulation of small glucan chains DP 6-10 reveal exponential fit curve with maximum R in smallest granule size starches (Chlamydomonas, quinoa, buckwheat). Cereal and cassava showed R of 0.81-0.96 while in pulses and tubers it was less than 0.7. The amylopectin small glucan chains form a unique 'finger print region' that identified starch botanical source. Differential amylopectin chain length distribution (APCLD) graphs between DP 6-80 of all species from Chlamydomonas starch distinguished five structural groups that clustered the 31 analyzed starches into four major patterns. APCLD analyses of amylopectin combined with characteristic pattern of small linear DP (6-9) glucan chains predicted the starch botanical source.
Topics: Amylopectin; Amylose; Chenopodium quinoa; Chlamydomonas; Edible Grain; Glucans; Manihot; Plant Tubers; Starch
PubMed: 28024534
DOI: 10.1016/j.carbpol.2016.11.059