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1.
BMC Plant Biol ; 21(1): 479, 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34674662

RESUMO

Starch branching enzymes (SBEs) are key determinants of the structure and amount of the starch in plant organs, and as such, they have the capacity to influence plant growth, developmental, and fitness processes, and in addition, the industrial end-use of starch. However, little is known about the role of SBEs in determining starch structure-function relations in economically important horticultural crops such as fruit and leafy greens, many of which accumulate starch transiently. Further, a full understanding of the biological function of these types of starches is lacking. Because of this gap in knowledge, this minireview aims to provide an overview of SBEs in horticultural crops, to investigate the potential role of starch in determining postharvest quality. A systematic examination of SBE sequences in 43 diverse horticultural species, identified SBE1, 2 and 3 isoforms in all species examined except apple, olive, and Brassicaceae, which lacked SBE1, but had a duplicated SBE2. Among our findings after a comprehensive and critical review of published data, was that as apple, banana, and tomato fruits ripens, the ratio of the highly digestible amylopectin component of starch increases relative to the more digestion-resistant amylose fraction, with parallel increases in SBE2 transcription, fruit sugar content, and decreases in starch. It is tempting to speculate that during the ripening of these fruit when starch degradation occurs, there are rearrangements made to the structure of starch possibly via branching enzymes to increase starch digestibility to sugars. We propose that based on the known action of SBEs, and these observations, SBEs may affect produce quality, and shelf-life directly through starch accumulation, and indirectly, by altering sugar availability. Further studies where SBE activity is fine-tuned in these crops, can enrich our understanding of the role of starch across species and may improve horticulture postharvest quality.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/genética , Produtos Agrícolas/enzimologia , Isoenzimas , Amido/metabolismo , Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Motivos de Aminoácidos , Amilopectina/metabolismo , Amilose/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/normas , Grão Comestível , Armazenamento de Alimentos , Frutas , Horticultura , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tubérculos , Açúcares/metabolismo , Verduras
2.
Biochemistry ; 60(31): 2425-2435, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34319705

RESUMO

Glucan phosphatases are members of a functionally diverse family of dual-specificity phosphatase (DSP) enzymes. The plant glucan phosphatase Starch Excess4 (SEX4) binds and dephosphorylates glucans, contributing to processive starch degradation in the chloroplast at night. Little is known about the complex kinetics of SEX4 when acting on its complex physiologically relevant glucan substrate. Therefore, we explored the kinetics of SEX4 against both insoluble starch and soluble amylopectin glucan substrates. SEX4 displays robust activity and a unique sigmoidal kinetic response to amylopectin, characterized by a Hill coefficient of 2.77 ± 0.63, a signature feature of cooperativity. We investigated the basis for this positive kinetic cooperativity and determined that the SEX4 carbohydrate-binding module (CBM) dramatically influences the binding cooperativity and substrate transformation rates. These findings provide insights into a previously unknown but important regulatory role for SEX4 in reversible starch phosphorylation and further advances our understanding of atypical kinetic mechanisms.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Fosfatases de Especificidade Dupla/química , Fosfatases de Especificidade Dupla/metabolismo , Glucanos/metabolismo , Monoéster Fosfórico Hidrolases/química , Monoéster Fosfórico Hidrolases/metabolismo , Sítio Alostérico/fisiologia , Amilopectina/química , Amilopectina/metabolismo , Brassica/química , Metabolismo dos Carboidratos , Glucanos/química , Cinética , Modelos Moleculares , Fosforilação , Ligação Proteica , Domínios Proteicos/fisiologia , Estabilidade Proteica , Solanum tuberosum/química
3.
Food Chem ; 362: 130188, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34090046

RESUMO

This study investigates the evolution of the distributions of whole molecular size and of chain length of granular wheat starches (37 ~ 93% amylose content), subjected to in vitro fermentation with a porcine faecal inoculum or digestion with pancreatic enzymes. The results showed that the molecular structures of high-amylose starch (HAS) unfermented residues largely remained unchanged during the fermentation process, while wild-type starch (37% amylose content) showed a preferential degradation of the amylopectin fraction. In contrast, under simulated digestion conditions, the undigested residues of HAS showed structural changes, including a decrease in amylose content, a shift of amylose peak position towards lower degrees of polymerisation, and an enzyme-resistant fraction. These changes of starch structure are likely to be dependent on the different starch-degrading enzyme activities present in pancreatic vs. microbial systems. Molecular changes in response to fermentation metabolism revealed by size-exclusion chromatography can help understand the microbial utilization of resistant starch.


Assuntos
Amilose/química , Amido/química , Amido/farmacocinética , Triticum/química , Amilopectina/química , Amilopectina/metabolismo , Amilopectina/farmacocinética , Animais , Digestão , Fezes/microbiologia , Fermentação , Estrutura Molecular , Polimerização , Amido/isolamento & purificação , Suínos
4.
Food Chem ; 362: 130203, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091172

RESUMO

In the crumb of fresh white wheat bread, starch is fully gelatinized. Its molecular and three-dimensional structure are major factors limiting the rate of its digestion. The aim of this study was to in situ modify starch during bread making with starch-modifying enzymes (maltogenic amylase and amylomaltase) and to investigate the impact thereof on bread characteristics, starch retrogradation and digestibility. Maltogenic amylase treatment increased the relative content of short amylopectin chains (degree of polymerization ≤ 8). This resulted in lower starch retrogradation and crumb firmness upon storage, and reduced extent (up to 18%) of in vitro starch digestion for fresh and stored breads. Amylomaltase only modestly shortened amylose chains and had no measurable impact on amylopectin structure. Modification with this enzyme led to slower bread crumb firming but did not influence starch digestibility.


Assuntos
Pão , Sistema da Enzima Desramificadora do Glicogênio/química , Glicosídeo Hidrolases/química , Amido/farmacocinética , Triticum , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Liofilização , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Glicosídeo Hidrolases/metabolismo , Amido/química , Triticum/química
5.
Int J Biol Macromol ; 183: 1248-1256, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-33965495

RESUMO

Potato starch with high viscosity and digestibility cannot be added into some foods. To address this issue, a novel starch-acting enzyme 4,6-α-glucosyltransferase from Streptococcus thermophilus (StGtfB) was used. StGtfB decreased the iodine affinity and the molecular weight, but increased the degree of branching of starch at a mode quite different from glycogen 1,4-α-glucan branching enzyme (GBE). StGtfB at 5 U/g substrate mainly introduced DP 1-7 into amylose (AMY) or DP 1-12 branches into amylopectin (AMP), and increased the ratio of short- to long-branches from 0.32 to 2.22 or from 0.41 to 2.50. The DP 3 branch chain was the most abundant in both StGtfB-modified AMY and StGtfB-modified AMP. The DP < 6 branch chain contents in StGtfB-modified AMY were 42.68%, much higher than those of GBE-modified AMY. StGtfB significantly decreased viscoelasticity but still kept pseudoplasticity of starch. The modifications also slowed down the glucose generation rate of products at the mammalian mucosal α-glucosidase level. The slowly digestible fraction in potato starch increased from 34.29% to 53.22% using StGtfB of 5 U/g starch. This low viscoelastic and slowly digestible potato starch had great potential with respect to low and stable postprandial blood glucose.


Assuntos
Glucosiltransferases/metabolismo , Solanum tuberosum/química , Amido/química , Streptococcus thermophilus/enzimologia , Amilopectina/metabolismo , Amilose/metabolismo , Proteínas de Bactérias/metabolismo , Elasticidade , Hidrólise , Iodo/química , Peso Molecular , Viscosidade
6.
Food Chem ; 359: 129954, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33964659

RESUMO

The contents of amylose and amylopectin in sorghum directly affects the quality and yield of liquor. Hyperspectral imaging (HSI) is an emerging technology widely applied in the content analysis of food ingredients. In this study, the effects of different preprocessing methods on visible-light and near-infrared spectral data were analyzed, and the prediction accuracies of these spectral data were compared. Principal components analysis (PCA) and successive projections algorithm (SPA) were combined to extract the characteristic wavelengths. Using both the full and characteristic wavelengths, partial least square regression (PLSR) and cascade forest (CF) models were developed to predict the contents of amylose and amylopectin in different varieties of sorghum. The average RPD values of the CF models established by the characteristic wavelengths were 4.7622 and 5.5889, respectively. These results corroborated the utility of HSI in achieving the rapid and nondestructive prediction of amylose and amylopectin contents in different varieties of sorghum.


Assuntos
Amilopectina/metabolismo , Amilose/metabolismo , Imageamento Hiperespectral/métodos , Sorghum/metabolismo , Algoritmos , Grão Comestível , Análise dos Mínimos Quadrados , Análise de Componente Principal
7.
Food Chem ; 356: 129665, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-33813206

RESUMO

The influence of natural fermentation on the highlands barley starch chemical structure, morphological, physicochemical, and thermal properties was studied. The findings showed that fermentation had no impact on starch fine structure but it decreased the molecular-weight from 2.26 to 1.04 × 108 g/mol in native highlands barley and after 72 h fermentation (FHB72) respectively. Also, it decreased amylopectin long-chains (B1 and B2) while increased short-chains. The intensity ratio of FT-IR at 995/1022 and 1047/1022 bands were found to be higher as the time of fermentation progressed, and the highest absorption-intensity at 3000-3600 cm-1 and higher swelling capacity were noticed in the starch of FHB72. During fermentation, pasting peak, final and setback viscosities were decreased. Microscopically, granules with more pores, damaged, cracked, and no growth rings were found in starches isolated after 48 h and 72 h of fermentation. This study indicated that fermentation up to 72 h is an effective method to modify highlands barley starch.


Assuntos
Hordeum/metabolismo , Amido/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Fermentação , Microscopia Confocal , Peso Molecular , Tamanho da Partícula , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Viscosidade
8.
J Plant Physiol ; 258-259: 153389, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33652172

RESUMO

Starch is a natural storage carbohydrate in plants and algae. It consists of two relatively simple homo-biopolymers, amylopectin and amylose, with only α-1,4 and α-1,6 linked glucosyl units. Starch is an essential source of nutrition and animal food, as well as an important raw material for industry. However, despite increasing knowledge, detailed information about its structure and turnover are largely lacking. In the last decades, most data were generated using bulk experiments, a method which obviously presents limitations regarding a deeper understanding of the starch metabolism. Here, we discuss some unavoidable questions arising from the existing data. We focus on a few examples related to starch biosynthesis, degradation, and structure - where these limitations strongly emerge. Closing these knowledge gaps will also be extremely important for taking the necessary steps in order to set up starch-providing crops for the challenges of the ongoing climate changes, as well as for increasing the usability of starches for industrial applications by biotechnology.


Assuntos
Amilopectina/metabolismo , Amilose/metabolismo , Produtos Agrícolas/metabolismo , Amilopectina/biossíntese , Amilose/biossíntese , Biopolímeros/metabolismo , Biotecnologia
9.
Int J Biol Macromol ; 180: 187-193, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33675831

RESUMO

Cyclodextrinase (CDase) and cyclodextrin glucosyltransferase (CGTase) were synergistically used to provide a novel enzymatic method in lowing in vitro digestibility of waxy maize starch. The molecular structure, malto-oligosaccharide composition, and digestibility properties of the generated products were investigated. The molecular weight was reduced to 0.3 × 105 g/mol and 0.2 × 105 g/mol by simultaneous and sequential treatment with CDase and CGTase, while the highest proportion of chains with degree of polymerization (DP) < 13 was obtained by simultaneous treatment. The resistant starch contents were increased to 27.5% and 36.9% by simultaneous and sequential treatments respectively. Dual-enzyme treatment significantly promoted the content of malto-oligosaccharides (MOSs) by hydrolyzing cyclodextrins from CGTase with CDase. However, the replacement of cyclodextrins by MOSs did not obviously influence the digestibility of the products. The starch digestion kinetics further revealed the hydrolysis pattern of these two enzymes on the starch hydrolysate. It was proved that the starch digestibility could be lowered by modulating the molecular structure and beneficial MOSs content by this dual-enzyme treatment.


Assuntos
Amilopectina/química , Amilopectina/metabolismo , Glucosiltransferases/metabolismo , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Glicosídeo Hidrolases/metabolismo , Oligossacarídeos/análise , Zea mays/química , Ciclodextrinas/metabolismo , Digestão , Sinergismo Farmacológico , Glucosiltransferases/farmacologia , Sistema da Enzima Desramificadora do Glicogênio/farmacologia , Glicosídeo Hidrolases/farmacologia , Hidrólise/efeitos dos fármacos , Cinética , Estrutura Molecular , Peso Molecular , Polimerização
10.
Int J Biol Macromol ; 180: 625-632, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33766589

RESUMO

The formation and structural evolution of starch nanocrystals from waxy maize starch (WMS) and waxy potato starch (WPS) by acid hydrolysis were studied. The relative crystallinity, the short-range molecular order, and the double-helix content of WMS and WPS increased significantly during the initial stage of acid hydrolysis, indicating that acid preferentially eroded the amorphous regions of starch granules. With time, there was increased destruction of lamellar structures, causing the granules to completely disintegrate to form nanocrystals. WMS and WPS displayed different hydrolysis mechanisms. WPS was more susceptible to acid hydrolysis than WMS, and WMS exhibited an endo-corrosion pattern and WPS showed an exo-corrosion pattern. WMS nanocrystals had a parallelepiped shape, and WPS nanocrystals were round. This difference in shape is likely due to the different packing configuration of double helices in native starches.


Assuntos
Nanopartículas/química , Solanum tuberosum/química , Amido/química , Ceras/química , Zea mays/química , Ácidos/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Amilose/metabolismo , Hidrólise , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Espalhamento a Baixo Ângulo , Solanum tuberosum/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/metabolismo , Amido/ultraestrutura , Ceras/metabolismo , Difração de Raios X , Zea mays/metabolismo
11.
J Agric Food Chem ; 69(4): 1206-1213, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33481586

RESUMO

Starch biosynthesis in cereal crops is a complex pathway regulated by multiple starch synthetic enzymes. Starch synthase IIa (SSIIa) is well-known to be one of the major starch synthases and is very important in amylopectin biosynthesis. It has significant effects on grain composition and kernel traits. However, there are few reports on the association of natural variation of SSIIa in barley and grain composition and characteristics. In this work, two SSIIa isoforms were first identified as SSIIaH and SSIIaL by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mass spectrometry, and Western blotting. Sequence analysis of the SSIIa gene demonstrated that a 33 bp insertion coding a peptide of APPSSVVPAKK caused different SSIIa, e.g., SSIIaH and SSIIaL. Based on this molecular difference, a polymerase chain reaction marker was developed, which could be used to screen different SSIIa genotypes easily. Kernel hardness of SSIIaL genotypes was significantly higher than that of SSIIaH Chinese barley cultivars. The proportion of SSIIaL genotypes was extremely low in Australian barley cultivars (5/24) and much higher in Tibetan hull-less barley cultivars (46/74), consistent with the end-use requirements of barley grain. This study provided new information in barley endosperm starch synthesis and indicated that it is valuable for choosing the preferred SSIIa genotype according to the end-use requirements.


Assuntos
Hordeum/enzimologia , Proteínas de Plantas/metabolismo , Sementes/química , Sintase do Amido/metabolismo , Sequência de Aminoácidos , Amilopectina/química , Amilopectina/metabolismo , Austrália , Hordeum/química , Hordeum/genética , Proteínas de Plantas/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Sementes/enzimologia , Sementes/genética , Amido/química , Amido/metabolismo , Sintase do Amido/genética
12.
J Sci Food Agric ; 101(6): 2428-2438, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33012027

RESUMO

BACKGROUND: In this study, we investigated the effects of water-nitrogen interaction on the grain quality of two varieties of japonica rice grown on the North China Plain, based on evaluations of grain biochemical components, starch X-ray diffraction properties, thermal and pasting characteristics, and particle size distribution. RESULTS: We found that, under controlled irrigation, increasing levels of nitrogen resulted in a reduction in grain starch content and an increase in protein content. Nitrogen fertilization, irrigation, and their interaction had significant effects on the particle size and size distribution of rice flour. Under both controlled and flooding irrigation, the lowest values of pasting parameters for cultivars Xindao22 and Xindao10 were observed in response to moderate and high nitrogen application, respectively. Under flooding irrigation, Xindao22 exhibited lower mean value of gelatinization onset, peak, and conclusion temperatures and enthalpy in response to control irrigation, whereas in Xindao10 these parameters were relatively stable with respect to nitrogen and irrigation treatments. However, we observed no significant effects of either nitrogen or irrigation on amylopectin chain length distribution or starch relative crystallinity. CONCLUSION: Nitrogen application rate and irrigation methods had distinct effects on the physicochemical properties of flour derived from treated rice plants. The findings will provide support for scientific irrigation and fertilization in order to improve rice grain quality. © 2020 Society of Chemical Industry.


Assuntos
Irrigação Agrícola/métodos , Produção Agrícola/métodos , Nitrogênio/metabolismo , Oryza/metabolismo , Sementes/química , Amilopectina/química , Amilopectina/metabolismo , China , Fertilizantes/análise , Nitrogênio/análise , Oryza/química , Oryza/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Amido/química , Amido/metabolismo
13.
J Sci Food Agric ; 101(9): 3811-3818, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33314139

RESUMO

BACKGROUND: Rice eating quality largely dictates consumer preference, and the demand for new rice varieties with excellent eating quality from farmers is increasing. Identification of factors contributing to eating quality is helpful for developing high-quality rice varieties. RESULTS: Two groups of rice with different apparent amylose content (AACs) were used in this study. One group contained four varieties with low AACs (8.8-9.4%), whereas the other contained four traditional varieties with medium AACs (17.2-17.5%). The physicochemical properties, starch fine structure and crystallinity and storage protein composition of the two groups were analyzed. We found that, in both groups, the rice varieties with high eating quality had more short-chain amylopectin, lower glutelin and prolamin content, and a higher albumin content. In addition, the low-AAC varieties produced opaque endosperms, which may result from an increased number of pores in the center of starch granules. CONCLUSIONS: Both the fine structure of starch and the storage protein composition were closely related to rice eating quality. In both groups, short branch-chain amylopectin, short-chain amylopectin [degree of polymerization (DP) 6-12], and albumin had positive effects on eating quality. By contrast, long branch-chain amylopectin, long-chain amylopectin (DP 35-60), glutelin and prolamin had adverse effects on eating quality of rice. © 2020 Society of Chemical Industry.


Assuntos
Oryza/química , Proteínas de Armazenamento de Sementes/química , Amido/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Amilose/metabolismo , Análise de Alimentos , Humanos , Oryza/classificação , Oryza/metabolismo , Sementes/química , Sementes/classificação , Sementes/metabolismo , Amido/metabolismo
14.
Food Chem ; 343: 128423, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33168261

RESUMO

The aim was to determine inhibition of human α-amylase activity by (poly)phenols using maltoheptaoside as substrate with direct chromatographic product quantification, compared to hydrolysis of amylose and amylopectin estimated using 3,5-dinitrosalicylic acid. Acarbose exhibited similar IC50 values (50% inhibition) with maltoheptaoside, amylopectin or amylose as substrates (2.37 ± 0.11, 3.71 ± 0.12 and 2.08 ± 0.01 µM respectively). Epigallocatechin gallate, quercetagetin and punicalagin were weaker inhibitors of hydrolysis of maltoheptaoside (<50% inhibition) than amylose (IC50: epigallocatechin gallate = 20.41 ± 0.25 µM, quercetagetin = 30.15 ± 2.05 µM) or amylopectin. Interference using 3,5-dinitrosalicylic acid was in the order punicalagin > epigallocatechin gallate > quercetagetin, with minimal interference using maltoheptaoside as substrate. The main inhibition mechanism of epigallocatechin gallate and punicalagin was through complexation with starch, especially amylose, whereas only quercetagetin additionally binds to the α-amylase active site. Interference is minimised using maltoheptaoside as substrate with product detection by chromatography, potentially allowing assessment of direct enzyme inhibition by almost any compound.


Assuntos
Cromatografia por Troca Iônica/métodos , Polifenóis/química , Amido/química , alfa-Amilases/metabolismo , Acarbose/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo , Domínio Catalítico , Catequina/análogos & derivados , Catequina/química , Flavonas/química , Humanos , Hidrólise , Taninos Hidrolisáveis/química , Oligossacarídeos/análise , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Polifenóis/metabolismo , Polifenóis/farmacologia , Salicilatos/metabolismo , Açúcares/metabolismo , alfa-Amilases/antagonistas & inibidores
15.
Int J Mol Sci ; 22(1)2020 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-33375157

RESUMO

Dendroctonus-bark beetles are natural agents contributing to vital processes in coniferous forests, such as regeneration, succession, and material recycling, as they colonize and kill damaged, stressed, or old pine trees. These beetles spend most of their life cycle under stem and roots bark where they breed, develop, and feed on phloem. This tissue is rich in essential nutrients and complex molecules such as starch, cellulose, hemicellulose, and lignin, which apparently are not available for these beetles. We evaluated the digestive capacity of Dendroctonusrhizophagus to hydrolyze starch. Our aim was to identify α-amylases and characterize them both molecularly and biochemically. The findings showed that D. rhizophagus has an α-amylase gene (AmyDr) with a single isoform, and ORF of 1452 bp encoding a 483-amino acid protein (53.15 kDa) with a predicted signal peptide of 16 amino acids. AmyDr has a mutation in the chlorine-binding site, present in other phytophagous insects and in a marine bacterium. Docking analysis showed that AmyDr presents a higher binding affinity to amylopectin compared to amylose, and an affinity binding equally stable to calcium, chlorine, and nitrate ions. AmyDr native protein showed amylolytic activity in the head-pronotum and gut, and its recombinant protein, a polypeptide of ~53 kDa, showed conformational stability, and its activity is maintained both in the presence and absence of chlorine and nitrate ions. The AmyDr gene showed a differential expression significantly higher in the gut than the head-pronotum, indicating that starch hydrolysis occurs mainly in the midgut. An overview of the AmyDr gene expression suggests that the amylolytic activity is regulated through the developmental stages of this bark beetle and associated with starch availability in the host tree.


Assuntos
Besouros/metabolismo , Trato Gastrointestinal/metabolismo , Pinus/parasitologia , Casca de Planta/parasitologia , Amido/metabolismo , alfa-Amilases/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo , Animais , Ligação Competitiva , Besouros/enzimologia , Besouros/genética , Trato Gastrointestinal/enzimologia , Regulação Enzimológica da Expressão Gênica , Hidrólise , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Ligação Proteica , alfa-Amilases/genética
16.
J Agric Food Chem ; 68(28): 7444-7452, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32551583

RESUMO

Amylopectin is an essential starch property, and the chain-length distribution of amylopectin (APCLD) is closely associated with the eating and cooking quality of rice. In this study, a series of recombinant inbred lines derived from an indica/japonica cross were planted in four areas with distinct ecological conditions (LN, SC, JS, and GD), and the relationship among APCLD, environmental factors, and genetic background was analyzed. The results showed that APCLD was strongly influenced by environmental factors, which dynamically changed from heading to the mature stage. The solar radiation, luminous flux, and light hours were positively correlated with Fa but negatively correlated with Fb1 and Fb2. The temperature was negatively correlated with Fa and Fb1 but positively correlated with Fb2 and Fb3. The temperature was the primary factor affecting APCLD, followed by humidity and light. There was no significant correlation between the indica pedigree percentage and APCLD. Furthermore, we detected six quantitative trait loci related to Fa, Fb1, Fb2, and Fb3 chains, several of which shared a similar region to previously reported loci, including DENSE AND ERECT PANICLE 1 (DEP1). The truncated dep1 allele increased Fa, Fb2, and Fb3 but decreased Fb1 in LN, whereas Fa was decreased but Fb1 and Fb2 were increased in JS. Elucidating the effects of climate factors and genetic background on APCLD could provide a theoretical basis and technical guidance for high-quality rice breeding.


Assuntos
Amilopectina/metabolismo , Oryza/genética , Amilopectina/química , Ecossistema , Endogamia , Oryza/química , Oryza/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas
17.
Int J Biol Macromol ; 155: 721-729, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32259539

RESUMO

Starch gelatinization is an endothermic transition arising during rice cooking, which significantly influences rice eating and cooking quality (ECQ). The nature of starch (especially amylose) fine molecular structures that gives rise to this endotherm is however currently unclear. A modified Gomperz model was developed in this study to fit the differential scanning calorimetry (DSC) thermograms, resulting complementary information to the traditional DSC parameters. Correlation analysis between DSC parameters with starch chain-length distributions (CLDs) from 14 different rice starches showed for the first time that although amylose CLDs didn't affect starch gelatinization temperatures, the relative length of amylose medium chains was negatively correlated with the gelatinization temperature range. Furthermore, gelatinization onset and peak temperature as well as maximum gelatinization rate were negatively correlated with the relative length of amylopectin short chains, while the conclusion temperature were related to the relative length of amylopectin medium chains. Based on these results, a model for the arrays of amylopectin and amylose molecules within semi-crystalline lamellas of rice starch granules was proposed. These results will enable plant breeders to produce rice with desirable ECQs based on better understandings of the importance of starch fine molecular structures in determining starch gelatinization property.


Assuntos
Amilopectina/química , Amilose/química , Gelatina/química , Oryza/química , Amilopectina/metabolismo , Amilose/metabolismo , Estrutura Molecular , Oryza/metabolismo , Temperatura
18.
Plant Sci ; 294: 110443, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32234229

RESUMO

High temperature (HT) is a main environmental restraint that affects rice yield and grain quality. In this study, SSIIIa-RNAi and its wild-type (WT) were used to investigate the effect of HT exposure on the isozyme-specific variation of several key starch biosynthesis enzymes in developing endosperms and its relation to starch properties. SSIIIa-RNAi had minimal impact on grain chalky occurrence under normal temperature growth, but it could up-grade the susceptibility of grain chalky occurrence to HT exposure, due to the relatively sensitive response of AGPase and SSI to HT exposure. Different from WT, SSIIIa-RNAi had the relatively enriched proportion of chains with DP 13-16 under HT, and HT-induced decline in the proportion of DP < 12 became much larger for SSIIIa-RNAi relative to WT. SSIIIa-RNAi significantly enhanced the expression of SSI isozyme and total SS activity, whereas SSI-RNAi deficiency had little impact on the expression of SSIIIa isozyme. In this regard, the compensatory increase in SSI isozyme as a result of SSIIIa deficiency occurred only in a one-way manner. SSIIIa-RNAi caused a striking elevation in BEIIa expression, and the effect of SSIIIa deficiency on the chain length distribution in relation to HT exposure was closely associated with the participation of BEIIa, SSI, and their interaction in amylopectin biosynthesis.


Assuntos
Oryza/metabolismo , Amido/metabolismo , Amilopectina/genética , Amilopectina/metabolismo , Temperatura Alta , Oryza/genética , Interferência de RNA/fisiologia , Amido/genética , Sintase do Amido/genética , Sintase do Amido/metabolismo , Temperatura
19.
Food Chem ; 324: 126855, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344341

RESUMO

To develop a 1,4-α-glucan branching enzyme (BE) without homology to known allergens, the glgB gene from Bifidobacterium longum was overexpressed under the control of BLMA promoter in Escherichia coli. B. longum BE (BlBE) had a molecular weight of 86.1 kDa and a specific activity of more than 18.5U/mg protein at 25-35 °C and pH 5.5-7.0, and exhibited 30% of the maximum activity at 10 °C. The cold-active BlBE preferred to transfer maltohexaose and introduced DP 4-36 branches into amylose. BlBE also increased the proportion of DP 2-10 branches in amylopectin and decreased its Mw from 1.39 × 106 to 1.16 × 105 g/mol. As the BlBE concentration increased from 0.0 to 0.5U/mg substrate, the retrogradation enthalpy of BlBE-modified wheat starch decreased from 4.50 to 1.83 J/g (p < 0.05) at day 14 and the slowly digestible starch content increased from 2.10% to 17.39% (p < 0.05).


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Bifidobacterium longum/enzimologia , Amido/metabolismo , Triticum/metabolismo , Enzima Ramificadora de 1,4-alfa-Glucana/classificação , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Sequência de Aminoácidos , Amilopectina/metabolismo , Escherichia coli/metabolismo , Concentração de Íons de Hidrogênio , Peso Molecular , Filogenia , Alinhamento de Sequência , Temperatura , Termodinâmica
20.
Food Chem ; 320: 126609, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32222658

RESUMO

Bread crumb firming is largely determined by the properties of gluten and starch, and the transformations they undergo during bread making and storage. Amylose (AM) and amylopectin (AP) functionality in fresh and stored bread was investigated with NMR relaxometry. Bread was prepared from flours containing normal and atypical starches, e.g., flour from wheat line 5-5, with or without the inclusion of Bacillus stearothermophilus α-amylase. Initial crumb firmness increased with higher levels of AM or shorter AM chains. Both less extended AM and gluten networks and too rigid AM networks led to low crumb resilience. AP retrogradation during storage increased when crumb contained more AP or longer AP branch chains. Shorter AP branch chains, which were present at higher levels in 5-5 than in regular bread, were less prone to retrogradation, thereby limiting gluten network dehydration due to gluten to starch moisture migration. Correspondingly, crumb firming in 5-5 bread was restricted.


Assuntos
Amilopectina/química , Amilose/química , Pão/análise , Armazenamento de Alimentos , Amilopectina/metabolismo , Amilose/metabolismo , Proteínas de Bactérias , Farinha/análise , Geobacillus stearothermophilus/enzimologia , Glutens/química , Espectroscopia de Ressonância Magnética , Amido/química , Triticum/química , Água , alfa-Amilases/metabolismo
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