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The New Phytologist Dec 2020Starch granules are composed of two distinct glucose polymers - amylose and amylopectin. Amylose constitutes 5-35% of most natural starches and has a major influence... (Review)
Review
Starch granules are composed of two distinct glucose polymers - amylose and amylopectin. Amylose constitutes 5-35% of most natural starches and has a major influence over starch properties in foods. Its synthesis and storage occurs within the semicrystalline amylopectin matrix of starch granules, this poses a great challenge for biochemical and structural analyses. However, the last two decades have seen vast progress in understanding amylose synthesis, including new insights into the action of GRANULE BOUND STARCH SYNTHASE (GBSS), the major glucosyltransferase that synthesises amylose, and the discovery of PROTEIN TARGETING TO STARCH1 (PTST1) that targets GBSS to starch granules. Advances in analytical techniques have resolved the fine structure of amylose, raising new questions on how structure is determined during biosynthesis. Furthermore, the discovery of wild plants that do not produce amylose revives a long-standing question of why starch granules contain amylose, rather than amylopectin alone. Overall, these findings contribute towards a full understanding of amylose biosynthesis, structure and function that will be essential for future approaches to improve starch quality in crops.
Topics: Amylopectin; Amylose; Glucans; Starch; Starch Synthase
PubMed: 32767769
DOI: 10.1111/nph.16858 -
The Journal of Biological Chemistry Jun 2022Not all starches in the human diet are created equal: "resistant starches" are consolidated aggregates of the α-glucan polysaccharides amylose and amylopectin, which...
Not all starches in the human diet are created equal: "resistant starches" are consolidated aggregates of the α-glucan polysaccharides amylose and amylopectin, which escape digestion by salivary and pancreatic amylases. Upon reaching the large intestine, resistant starches become fodder for members of the human gut microbiota, impacting the metabolism of both the symbionts and the host. In a recent study, Koropatkin et al. provided new molecular insight into how a keystone bacterium in the human gut microbiota adheres to resistant starches as a prelude to their breakdown and fermentation.
Topics: Amylopectin; Amylose; Gastrointestinal Microbiome; Glucans; Humans; Starch; alpha-Amylases
PubMed: 35597281
DOI: 10.1016/j.jbc.2022.102049 -
Molecules (Basel, Switzerland) Nov 2023In the last few decades, theoretical and technical advancements in computer facilities and computational techniques have made molecular modeling a useful tool in... (Review)
Review
In the last few decades, theoretical and technical advancements in computer facilities and computational techniques have made molecular modeling a useful tool in liquid-phase enantioseparation science for exploring enantioselective recognition mechanisms underlying enantioseparations and for identifying selector-analyte noncovalent interactions that contribute to binding and recognition. Because of the dynamic nature of the chromatographic process, molecular dynamics (MD) simulations are particularly versatile in the visualization of the three-dimensional structure of analytes and selectors and in the unravelling of mechanisms at molecular levels. In this context, MD was also used to explore enantioseparation processes promoted by amylose and cellulose-based selectors, the most popular chiral selectors for liquid-phase enantioselective chromatography. This review presents a systematic analysis of the literature published in this field, with the aim of providing the reader with a comprehensive picture about the state of the art and what is still missing for modeling cellulose benzoates and the phenylcarbamates of amylose and cellulose and related enantioseparations with MD. Furthermore, advancements and outlooks, as well as drawbacks and pitfalls still affecting the applicability of MD in this field, are also discussed. The importance of integrating theoretical and experimental approaches is highlighted as an essential strategy for profiling mechanisms and noncovalent interaction patterns.
Topics: Cellulose; Amylose; Molecular Dynamics Simulation; Chromatography, High Pressure Liquid; Stereoisomerism; Phenylcarbamates
PubMed: 37959839
DOI: 10.3390/molecules28217419 -
Genes & Genetic Systems Oct 2006The major components of storage starch are amylose and amylopectin, and in wheat, both an amylose-free mutant lacking granule-bound starch synthase I and a high-amylose...
The major components of storage starch are amylose and amylopectin, and in wheat, both an amylose-free mutant lacking granule-bound starch synthase I and a high-amylose mutant lacking starch synthase IIa have been produced recently. Here, we report the production of an amylose-free/ high-amylose double mutant. This double mutant has kernel and carbohydrate characteristics that are remarkably different than those of either single mutant, including a dramatically shrunken seed shape. Surprisingly, the double mutant has maltose and sucrose levels that are high enough to make it worthy of being called "sweet wheat".
Topics: Amylose; Mutation; Plant Proteins; Starch Synthase; Triticum
PubMed: 17159298
DOI: 10.1266/ggs.81.361 -
Journal of Genetics Apr 2014Starch accumulates in plants as granules in chloroplasts of source organs such as leaves (transitory starch) or in amyloplasts of sink organs such as seeds, tubers and... (Review)
Review
Starch accumulates in plants as granules in chloroplasts of source organs such as leaves (transitory starch) or in amyloplasts of sink organs such as seeds, tubers and roots (storage starch). Starch is composed of two types of glucose polymers: the essentially linear polymer amylose and highly branched amylopectin. The amylose content of wheat and rice seeds is an important quality trait, affecting the nutritional and sensory quality of two of the world's most important crops. In this review, we focus on the relationship between amylose biosynthesis and the structure, physical behaviour and functionality of wheat and rice grains. We briefly describe the structure and composition of starch and then in more detail describe what is known about the mechanism of amylose synthesis and how the amount of amylose in starch might be controlled. This more specifically includes analysis of GBSS alleles, the relationship between waxy allelic forms and amylose, and related quantitative trait loci. Finally, different methods for increasing or lowering amylose content are evaluated.
Topics: Amylose; Genetic Engineering; Nutritive Value; Oryza; Quantitative Trait Loci; Starch; Triticum
PubMed: 24840849
DOI: 10.1007/s12041-014-0325-8 -
Carbohydrate Polymers Mar 2013Starch is an agricultural raw material used in many food and industrial products. It is present in granules that vary in shape in the form of amylose and amylopectin.... (Review)
Review
Starch is an agricultural raw material used in many food and industrial products. It is present in granules that vary in shape in the form of amylose and amylopectin. Starch-degrading enzymes are used on a large scale in the production of sweeteners (high fructose corn syrup) and concentrated glucose syrups as substrate for the fermentative production of bioethanol and basic chemicals. Over the last two decades α-glucanotransferases (EC 2.4.1.xx), such as branching enzyme (EC 2.4.1.18) and 4-α-glucanotransferase (EC 2.4.1.25), have received considerable attention. These enzymes do not hydrolyze the starch as amylases do. Instead, α-glucanotransferases remodel parts of the amylose and amylopectin molecules by cleaving and reforming α-1,4- and α-1,6-glycosidic bond. Here we review the properties of α-glucanotransferases and discuss the emerging use of these enzymes in the generation of novel starch derivatives.
Topics: 1,4-alpha-Glucan Branching Enzyme; Amylopectin; Amylose; Bacteria; Bacterial Proteins; Biocatalysis; Food Industry; Glucosyltransferases; Glycogen Debranching Enzyme System; Hydrolysis; Molecular Conformation; Molecular Weight; Time Factors
PubMed: 23465909
DOI: 10.1016/j.carbpol.2012.01.065 -
Wiley Interdisciplinary Reviews.... Mar 2017Interest in amylose and its hybrids has grown over many decades, and a great deal of work has been devoted to developing methods for designing functional amylose... (Review)
Review
Interest in amylose and its hybrids has grown over many decades, and a great deal of work has been devoted to developing methods for designing functional amylose hybrids. In this context, phosphorylase-catalyzed polymerization shows considerable promise as a tool for preparing diverse amylose hybrids. Recently, advances have been made in the chemoenzymatic synthesis and characterization of amylose-block-polymers, amylose-graft-polymers, amylose-modified surfaces, hetero-oligosaccharides, and cellodextrin hybrids. Many of these saccharides provide clear opportunities for advances in biomaterials because of their biocompatibility and biodegradability. Important developments in bioapplications of amylose hybrids have also been made, and such newly developed amylose hybrids will help promote the development of new generations of glyco materials. WIREs Nanomed Nanobiotechnol 2017, 9:e1423. doi: 10.1002/wnan.1423 For further resources related to this article, please visit the WIREs website.
Topics: Amylose; Biocompatible Materials; Glycogen; Metabolic Engineering; Phosphorylases; Polymerization
PubMed: 27506150
DOI: 10.1002/wnan.1423 -
Annual Review of Food Science and... Mar 2023Starch is one of the most abundant renewable biopolymers in nature and is the main constituent in the human diet and a raw material for the food industry. Native... (Review)
Review
Starch is one of the most abundant renewable biopolymers in nature and is the main constituent in the human diet and a raw material for the food industry. Native starches are limited in most industrial applications and often tailored by structural modification to enhance desirable attributes, minimize undesirable attributes, or create new attributes. Enzymatic approaches for structuring starch have become of interest to the food industry precisely because the reactions minimize the formation of undesirable by-products and coproducts and are therefore considered environmentally friendly methods for producing clean-label starches with better behavioral characteristics. Starches with improved functionalities for various applications are produced via enzyme hydrolysis and transfer reactions. Use of novel, multifunctional, starch-active enzymes to alter the structures of amylose and/or amylopectin molecules, and thus alter the starch's physiochemical attributes in a predictable and controllable manner, has been explored. This review provides state-of-the-art information on exploiting glycosyl transferases and glycosyl hydrolases for structuring starch to improve its functionalities. The characteristics of starch-active enzymes (including branching enzymes, amylomaltases, GH70 α-transglycosylases, amylosucrases, maltogenic amylases, cyclomaltodextrinases, neopullulanases, and maltooligosaccharide-forming amylases), structure-functionality-driven processing strategies, novel conversion products, and potential industrial applications are discussed.
Topics: Humans; Starch; Amylopectin; Amylose; Amylases; Hydrolysis
PubMed: 36525688
DOI: 10.1146/annurev-food-072122-023510 -
The Journal of Nutrition Jan 2023High amylose starchy foods modulate the postprandial metabolic response in humans. However, the mechanisms of their metabolic benefits and their impact on the subsequent... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
High amylose starchy foods modulate the postprandial metabolic response in humans. However, the mechanisms of their metabolic benefits and their impact on the subsequent meal have not been fully elucidated.
OBJECTIVE
We aimed to evaluate whether glucose and insulin responses to a standard lunch are influenced by the consumption of amylose-rich bread at breakfast in overweight adults and whether changes in plasma short chain fatty acids (SCFAs) concentrations contribute to their metabolic effects.
METHODS
Using a randomized crossover design, 11 men and 9 women, BMI 30 ± 3 kg/m, 48 ± 19 y, consumed at breakfast 2 breads made with high amylose flour (HAF): 85%-HAF (180 g) and 75%-HAF (170 g), and control bread (120 g) containing 100% conventional flour. Plasma samples were collected at fasting, 4 h after breakfast, and 2 h after a standard lunch to measure glucose, insulin, and SCFA concentrations. ANOVA posthoc analyses were used for comparisons.
RESULTS
Postprandial plasma glucose responses were 27% and 39% lower after breakfasts with 85%- and 70%-HAF breads than control bread (P = 0.026 and P = 0.003, respectively), with no difference after lunch. Insulin responses were not different between the 3 breakfasts, whereas there was a 28% lower response after the lunch following breakfast with 85%-HAF bread than the control (P = 0.049). Propionate concentrations increased from fasting by 9% and 12% 6 h after breakfasts with 85%- and 70%-HAF breads and decreased by 11% with control bread (P < 0.05). At 6 h after breakfast with 70%-HAF bread, plasma propionate and insulin were inversely correlated (r = -0.566; P = 0.044).
CONCLUSIONS
Amylose-rich bread reduces the postprandial glucose response after breakfast and insulin concentrations after the subsequent lunch in overweight adults. This second meal effect may be mediated by the elevation of plasma propionate due to intestinal fermentation of resistant starch. High amylose products could be a promising tool in a dietary prevention strategy for type 2 diabetes.
THIS TRIAL WAS REGISTERED AT CLINICAL TRIAL REGISTRY AS
NCT03899974 (https://www.
CLINICALTRIALS
gov/ct2/show/NCT03899974).
Topics: Adult; Female; Humans; Male; Amylose; Blood Glucose; Bread; Breakfast; Cross-Over Studies; Glucose; Insulin; Insulin, Regular, Human; Overweight; Postprandial Period; Propionates; Triticum
PubMed: 36913446
DOI: 10.1016/j.tjnut.2022.10.007 -
Plant Communications May 2022Resistant starch (RS), a healthy dietary fiber, is a particular type of starch that has attracted much research attention in recent years. RS has important roles in... (Review)
Review
Resistant starch (RS), a healthy dietary fiber, is a particular type of starch that has attracted much research attention in recent years. RS has important roles in reducing glycemic index, postprandial blood glucose levels, and serum cholesterol levels, thereby improving and preventing many diseases, such as diabetes, obesity, and cardiovascular disease. The formation of RS is influenced by intrinsic properties of starch (e.g., starch granule structure, starch crystal structure, and amylose-to-amylopectin ratio) and non-starch components (e.g., proteins, lipids, and sugars), as well as storage and processing conditions. Recent studies have revealed that several starch-synthesis-related genes (SSRGs) are crucial for the formation of RS during seed development. Several transcription factors and mRNA splicing factors have been shown to affect the expression or splicing of SSRGs that regulate RS content, suggesting their potential roles in RS formation. This review focuses mainly on recent research progress on the genetic regulation of RS content and discusses the emerging genetic and molecular mechanisms of RS formation in rice.
Topics: Amylopectin; Amylose; Oryza; Resistant Starch; Starch
PubMed: 35576157
DOI: 10.1016/j.xplc.2022.100329