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Nature Communications Aug 2022The gut microbiome is an important determinant in various diseases. Here we perform a cross-sectional study of Japanese adults and identify the Blautia genus, especially...
The gut microbiome is an important determinant in various diseases. Here we perform a cross-sectional study of Japanese adults and identify the Blautia genus, especially B. wexlerae, as a commensal bacterium that is inversely correlated with obesity and type 2 diabetes mellitus. Oral administration of B. wexlerae to mice induce metabolic changes and anti-inflammatory effects that decrease both high-fat diet-induced obesity and diabetes. The beneficial effects of B. wexlerae are correlated with unique amino-acid metabolism to produce S-adenosylmethionine, acetylcholine, and L-ornithine and carbohydrate metabolism resulting in the accumulation of amylopectin and production of succinate, lactate, and acetate, with simultaneous modification of the gut bacterial composition. These findings reveal unique regulatory pathways of host and microbial metabolism that may provide novel strategies in preventive and therapeutic approaches for metabolic disorders.
Topics: Acetylcholine; Administration, Oral; Adult; Amylopectin; Animals; Carbohydrate Metabolism; Clostridiales; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Diet, High-Fat; Gastrointestinal Microbiome; Humans; Japan; Mice; Mice, Inbred C57BL; Obesity; Ornithine; Symbiosis
PubMed: 35982037
DOI: 10.1038/s41467-022-32015-7 -
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 -
3 Biotech Mar 2022Maize possesses wide variation in amylose and amylopectin which assumes significance as a part of both food-chain and different industrial applications. Estimation of...
Maize possesses wide variation in amylose and amylopectin which assumes significance as a part of both food-chain and different industrial applications. Estimation of amylose and amylopectin in maize kernels is important for developing suitable hybrids. The existing protocols for estimation of amylose and amylopectin in maize are elaborate and lengthy, and involve high cost. Here, we developed a rapid and cost-effective method for estimation of amylose and amylopectin in maize kernels. 10% toluene and 80% ethanol were used for removal of proteins (~ 10%) and lipids (~ 4%) from maize flour. The over-estimation of amylose was minimized using NaOH with KI to stop free KI to bind with amylopectin. Standards were improved by mixing amylose and amylopectin in different concentrations (0-100%), rather than using amylose or amylopectin alone. Standard curve generated regression equation of = 90.436 + 0.8535 with = 0.9989. Two types of samples viz., (1) protein, amylose and amylopectin (2) amylose and amylopectin, showed that starch fractions were highly comparable to expected values with correlation coefficient () of 0.9998 and mean standard deviation of 0.54. The protocol successfully estimated wide range of amylose (2.79-50.04%) and amylopectin (59.96-97.21%) among diverse maize inbreds including () and () mutants. Present protocol required 75% less time and 92.5% less cost compared to existing protocols. The newly developed method would be highly useful in developing maize hybrids high in amylose or amylopectin. This is the first report of rapid and cost-effective protocol for estimation of starch fractions in maize kernels.
PubMed: 35186659
DOI: 10.1007/s13205-022-03128-z -
Plants (Basel, Switzerland) Dec 2021Corn starch serves as food, feed, and a raw material for industrial use. Starch makes up most of the biomass of the corn hybrid and is the most important and main yield... (Review)
Review
Corn starch serves as food, feed, and a raw material for industrial use. Starch makes up most of the biomass of the corn hybrid and is the most important and main yield component in corn breeding programs. Starch is composed of two polymers, branched amylopectin and linear amylose, which normally constitute about 75% and 25% of the corn starch, respectively. Breeding for corn starch quality has become economically beneficial because of the development of niche markets for specialty grains. In addition, due to the increased demands of biofuel production, corn ethanol production is receiving more attention. Consequently, improving starch quantity has become one of the most important breeding objectives. This review will summarize the use of corn starch, and the genetics and breeding of grain quality and quantity for industrial applications.
PubMed: 35009095
DOI: 10.3390/plants11010092 -
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 -
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 -
Cellular and Molecular Life Sciences :... Jul 2016Starch-rich crops form the basis of our nutrition, but plants have still to yield all their secrets as to how they make this vital substance. Great progress has been... (Review)
Review
Starch-rich crops form the basis of our nutrition, but plants have still to yield all their secrets as to how they make this vital substance. Great progress has been made by studying both crop and model systems, and we approach the point of knowing the enzymatic machinery responsible for creating the massive, insoluble starch granules found in plant tissues. Here, we summarize our current understanding of these biosynthetic enzymes, highlighting recent progress in elucidating their specific functions. Yet, in many ways we have only scratched the surface: much uncertainty remains about how these components function together and are controlled. We flag-up recent observations suggesting a significant degree of flexibility during the synthesis of starch and that previously unsuspected non-enzymatic proteins may have a role. We conclude that starch research is not yet a mature subject and that novel experimental and theoretical approaches will be important to advance the field.
Topics: Enzymes; Phosphorylation; Plant Cells; Starch; Substrate Specificity
PubMed: 27166931
DOI: 10.1007/s00018-016-2250-x -
Polymers Aug 2022Amylopectin from waxy corn and the three nanosized amylopectin fragments (NAFs)-NAF(56), NAF(20), and NAF(8)-from waxy corn starch with a hydrodynamic diameter of 227,...
Amylopectin from waxy corn and the three nanosized amylopectin fragments (NAFs)-NAF(56), NAF(20), and NAF(8)-from waxy corn starch with a hydrodynamic diameter of 227, 56, 20, and 8 nm, respectively, were randomly labeled with 1-pyrenebutyric acid. The efficiency of these pyrene-labeled amylopectin-based polysaccharides (Py-APS) for pyrene excimer formation (PEF) upon diffusive encounter between an excited and a ground-state pyrene increased with increasing concentration of unlabeled NAF(56) in Py-APS dispersions in DMSO. Fluorescence decay analysis of the Py-APS dispersions in DMSO prepared with increasing [NAF(56)] yielded the maximum number () of anhydroglucose units (AGUs) separating two pyrene-labeled AGUs while still allowing PEF. Comparison of with , obtained by conducting molecular mechanics optimizations on helical oligosaccharide constructs with HyperChem, led to a relationship between the interhelical distance () in a cluster of oligosaccharide helices, [NAF(56)], and the number of helices in a cluster. It was found that the APSs were composed of building blocks made of 3.5 (±0.9) helices that self-assembled into increasingly larger clusters with increasing [NAF(56)]. The ability of PEF-based experiments to yield the cluster size of APSs provides a new experimental means to probe the interior of APSs at the molecular level.
PubMed: 36015675
DOI: 10.3390/polym14163418 -
Bioengineered 2013Pullulanases are endo-acting enzymes capable of hydrolyzing α-1, 6-glycosidic linkages in starch, pullulan, amylopectin, and related oligosaccharides, while... (Review)
Review
Pullulanases are endo-acting enzymes capable of hydrolyzing α-1, 6-glycosidic linkages in starch, pullulan, amylopectin, and related oligosaccharides, while amylopullulanases are bifunctional enzymes with an active site capable of cleaving both α-1, 4 and α-1, 6 linkages in starch, amylose and other oligosaccharides, and α-1, 6 linkages in pullulan. The amylopullulanases are classified in GH13 and GH57 family enzymes based on the architecture of catalytic domain and number of conserved sequences. The enzymes with two active sites, one for the hydrolysis of α-1, 4- glycosidic bond and the other for α-1, 6-glycosidic bond, are called α-amylase-pullulanases, while amylopullulanases have only one active site for cleaving both α-1, 4- and α-1, 6-glycosidic bonds. The amylopullulanases produced by bacteria find applications in the starch and baking industries as a catalyst for one step starch liquefaction-saccharification for making various sugar syrups, as antistaling agent in bread and as a detergent additive.
Topics: Amino Acid Sequence; Amylopectin; Bacteria; Bacterial Proteins; Catalytic Domain; Conserved Sequence; Glucans; Glycoside Hydrolases; Molecular Sequence Data; Recombinant Proteins; Starch
PubMed: 23645215
DOI: 10.4161/bioe.24629