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1.
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
2.
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
3.
Food Chem ; 316: 126036, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32062574

RESUMO

Amylopectin internal part refers to the part between the reducing end and the outmost branches. The importance of amylopectin internal structure affecting starch gelatinization and retrogradation as well as enzyme susceptibility of retrograded starch was explored. A total of 13 different starches from a range of plants were used. Great variations in the structure and properties of these starches were obtained. Longer lengths of internal chain segments (e.g., total internal chain length) and more long internal chains (e.g., B3-chains) of amylopectins were related to more ordered physical structure in native and retrograded starches. More clustered A-chains contributed to more ordered physical structure in the starches. The more ordered structure was reflected by a higher thermal stability and melting enthalpy changes of the starches. It was also related to a higher resistance to enzyme hydrolysis of the retrograded starches.


Assuntos
Amilopectina/química , Amilose/química , Gelatina/química , Glucana 1,4-alfa-Glucosidase/metabolismo , beta-Amilase/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo , Hidrólise , Estrutura Molecular , Termodinâmica
4.
Food Chem ; 311: 125879, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31734012

RESUMO

Chlorogenic acid (CA) performs numerous bioactivities; however, its usage is currently limited because of low stability and poor bioaccessibility. In this study, a amylopectin-CA complex was formed. FTIR studies confirmed that the new complex formed via hydrogen and CH-π bonding, and was involved with the reorganization of the skeletal α-1,4 glucosidic linkages of amylopectin. DSC and XRD studies suggested that complexation affected starch crystallinity and increased the size of the amorphous region. Under high temperature, complex degradation followed first-order reaction kinetics whereas under low acidity, the complex retained maximum CA content at pH 2.5. In vitro gastrointestinal (GI) digestion studies showed that maximum digestion of the complex took place during the gastric phase (39%). In addition, 81.14% of the retained CA was absorbed after GI digestion. In conclusion, amylopectin complexation may improve the stability of CA during digestion and under various food-processing operations.


Assuntos
Amilopectina/química , Ácido Clorogênico/química , Amilopectina/metabolismo , Amilose/química , Varredura Diferencial de Calorimetria , Ácido Clorogênico/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Solubilidade , Amido/química , Temperatura
5.
Food Chem ; 311: 125972, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31864180

RESUMO

Three bacterial glycogen branching enzymes (GBEs) having different branching characteristics were used to produce clustered amylopectin (CAP), and structure and functional properties of CAPs were intensively analyzed. Branch distributions of three CAPs varied from very short (DPn = 6.65) to medium (DPn = 14.1). Branch distribution showed profound correlation with hydrodynamic diameter, water solubility, digestibility, and effects on mice gut-microbiota. All the CAPs showed nearly no viscosity and retrogradation. The very short-branch CAP exhibited more than 100-fold water-solubility, 3.5-fold lower α-amylase catalytic efficiency, and 27% lower digestibility in small intestine-mimicking condition than amylopectin. Intriguingly, medium branch CAP had 1.8-fold larger hydrodynamic diameter than the very short one. Mice gut-microbiota composition statistically varied after 12-day feeding of the CAPs, but only the medium chain CAP brought clear positive changes on the gut-microbiota. Consequently, slowly digestible starch was successfully synthesized by the single GBE, but the CAP structure affects in vivo functions in complicated manner.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Amilopectina/química , Amilopectina/metabolismo , Amilopectina/farmacologia , Animais , Microbioma Gastrointestinal/efeitos dos fármacos , Hidrodinâmica , Hidrólise , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Solubilidade , Viscosidade
6.
Arch Biochem Biophys ; 680: 108235, 2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31877265

RESUMO

Chlamydomonas reinhardtii is the best known unicellular green alga model which has long been used to investigate all kinds of cellular processes, including starch metabolism. Here we identified and characterized a novel enzyme, ChlreSEX4, orthologous to glucan phosphatase SEX4 from Arabidopsis thaliana, that is capable of binding and dephosphorylating amylopectin in vitro. We also reported that cysteine 224 and tryptophan 305 residues are critical for enzyme catalysis and substrate binding. Furthermore, we verified that ChlreSEX4 gene is expressed in vivo and that glucan phosphatase activity is measurable in Chlamydomonas protein extracts. In view of the results presented, we suggest ChlreSEX4 as a functional phosphoglucan phosphatase from C. reinhardtii. Our data obtained so far contribute to understanding the phosphoglucan phosphatases evolutionary process in the green lineage and their role in starch reversible phosphorylation. In addition, this allows to position Chlamydomonas as a potential tool to obtain starches with different degrees of phosphorylation for industrial or biotechnological purposes.


Assuntos
Chlamydomonas reinhardtii/metabolismo , Clorófitas/metabolismo , Glucanos/metabolismo , Proteínas de Plantas/metabolismo , Sequência de Aminoácidos , Amilopectina/metabolismo , Chlamydomonas reinhardtii/química , Clorófitas/química , Glucanos/química , Modelos Moleculares , Fosforilação , Proteínas de Plantas/química , Especificidade por Substrato
7.
PLoS One ; 14(10): e0223783, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31603940

RESUMO

Starch is synthesized from a series of reactions catalyzed by enzymes. ADP-glucose pyrophosphorylase (AGPase) initiates the synthesis pathway and synthesizes ADP-glucose, the substrate of starch synthase (SS), of which SSIV is an isoform. Mutations of the AGPase subunit and SSIV-coding genes affect starch content and cause variation in the number of granules. Here, we pyramided the functional mutation alleles of the AGPase subunit gene TaAGP.L-B1 and the SSIV-coding gene TaSSIVb-D to elucidate their synergistic effects on other key starch biosynthesis genes and their impact on starch content. Both the TaAGP.L-B1 and TaSSIVb-D genes were expressed in wheat grain development, and the expression level of TaAGP.L-B1 was higher than that of TaSSIVb-D. The TaAGP.L-B1 gene was downregulated in the agp.L-B1 single and agp.L-B1/ssIV-D double mutants at 12 to 18 days after flowering (DAF). TaSSIVb-D expression was significantly reduced at 6 DAF in both ssIV-D single and double mutants. In the agp.L-B1/ssIV-D double mutant, TaGBSSII was upregulated, while TaAGPSS, TaSSI, and TaSBEII were downregulated. Under the interaction of these genes, the total starch and amylopectin contents were significantly decreased in agp.L-B1 and agp.L-B1/ssIV-D mutants. The results suggested that the mutations of TaAGP.L-B1 and TaSSIVb-D genes resulted in variation in the expression patterns of the other four starch synthetic genes and led to a reduction in starch and amylopectin contents. These mutants could be used further as germplasm for resistant starch analysis.


Assuntos
Glucose-1-Fosfato Adenililtransferase/genética , Mutação , Sintase do Amido/genética , Amido/biossíntese , Triticum/crescimento & desenvolvimento , Amilopectina/metabolismo , Vias Biossintéticas , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Glucose-1-Fosfato Adenililtransferase/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sintase do Amido/metabolismo , Triticum/genética , Triticum/metabolismo
8.
Plant Physiol Biochem ; 142: 440-451, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31419646

RESUMO

Drought stress during the grain filling stage severely affects the quality and quantity of starch in rice grains. The enzymes such as ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) and starch synthase (SS, EC 2.4.1.21) are the key regulatory enzymes involved in the starch biosynthesis. In this study, the activity of the AGPase and starch synthase (SS) was correlated with the qualitative and quantitative parameters such as sucrose, starch, amylose, amylopectin, and resistant starch in leaves, roots, and grains of drought tolerant (N22) and drought susceptible (IR64) cultivars under applied water deficit stress (WDS). Drought stress enhanced the remobilization of stored starch from leaves to developing rice grains which was positively correlated with a decrease in the starch and starch synthase activity in leaves. Starch accumulation in developing grains was positively correlated with an increase in the AGPase and SS activity under drought. It was found that starch, amylopectin, and sucrose content in developing grains increased under water deficit stress (WDS), while amylose content decreased in both the varieties. However, in leaves, the SS activity decreased while AGPase activity was found to be increased under WDS in both varieties. Decreased starch content in matured grains was due to shortening of grain filling stage as drought stress caused early plant senescence. Yield reduction under drought was more in susceptible variety IR64 as compared to tolerant genotype N22.


Assuntos
Grão Comestível/metabolismo , Oryza/metabolismo , Amido/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo , Desidratação , Grão Comestível/fisiologia , Oryza/fisiologia , Fotossíntese , Folhas de Planta/metabolismo , Sacarose/metabolismo
9.
Food Chem ; 301: 125271, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31376690

RESUMO

Mature endosperm was separated regionally into different parts in three rice cultivars, Te-qing (TQ), Wu-xiang 9915 (WX9915) and Guang-ling-xiang-nuo (GLXN), and their transgenic lines with inhibition of starch branching enzyme I and IIb (SBEI/IIb-). Within the three wild-type cultivars, starches from endosperm different regions showed similar molecular and crystalline structures. However, in rices with inhibition of SBEs, amylopectin short branch-chain content and branching degree gradually decreased, but amylopectin B3+ chain content and average chain length increased gradually from the interior to exterior of endosperm. The amylose content gradually increased from the interior to exterior of endosperm in TQ- and WX9915-SBEI/II- lines. From the interior to exterior of endosperm, starch changed gradually from CC- to CB-type in TQ-SBEI/II- line and from CA- to CC-type in GLXN-SBEI/II- line, and remained CA-type in WX9915-SBEI/II- line. These results provided some information for quality breeding and utilizations of rice with inhibition of SBE.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/antagonistas & inibidores , Endosperma/enzimologia , Oryza/enzimologia , Amido/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/análise , Endosperma/efeitos dos fármacos , Oryza/química , Oryza/efeitos dos fármacos , Oryza/metabolismo , Amido/metabolismo
10.
Plant Cell Physiol ; 60(12): 2692-2706, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31397873

RESUMO

Abiotic environmental stresses have a negative impact on the yield and quality of crops. Understanding these stresses is an essential enabler for mitigating breeding strategies and it becomes more important as the frequency of extreme weather conditions increases due to climate change. This study analyses the response of barley (Hordeum vulgare L.) to a heat wave during grain filling in three distinct stages: the heat wave itself, the return to a normal temperature regime, and the process of maturation and desiccation. The properties and structure of the starch produced were followed throughout the maturational stages. Furthermore, the key enzymes involved in the carbohydrate supply to the grain were monitored. We observed differences in starch structure with well-separated effects because of heat stress and during senescence. Heat stress produced marked effects on sucrolytic enzymes in source and sink tissues. Early cessation of plant development as an indirect consequence of the heat wave was identified as the major contributor to final yield loss from the stress, highlighting the importance for functional stay-green traits for the development of heat-resistant cereals.


Assuntos
Amilopectina/metabolismo , Parede Celular/enzimologia , Parede Celular/metabolismo , Hordeum/enzimologia , Hordeum/metabolismo , beta-Frutofuranosidase/metabolismo , Amilopectina/genética , Parede Celular/fisiologia , Resposta ao Choque Térmico/fisiologia , Hordeum/fisiologia , beta-Frutofuranosidase/genética
11.
Food Chem ; 295: 484-492, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174785

RESUMO

The eating and cooking quality (ECQ) of stored rice grains is significantly affected by ageing, but the molecular mechanisms for this are not well understood. In the present study, changes of starch hierarchical structures and thermal properties of starch were investigated for rices with up to 12 months storage. For the first time, it was seen that storage resulted in molecular degradation of starch. This mainly involved shorter amylose chains and around (1 → 6)-α glycosidic branching points of amylopectin, which altered the crystalline structure. This resulted in lower gelatinization temperatures and enthalpy but higher crystalline heterogeneity. The ageing effect was varietally-dependent. The information obtained from this study offers improved molecular-level understanding of the effects of ageing process on rice cooking and eating qualities.


Assuntos
Armazenamento de Alimentos , Oryza/química , Amido/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Amilose/metabolismo , Cromatografia em Gel , Culinária , Gelatina/química , Gelatina/metabolismo , Microscopia Eletrônica de Varredura , Estrutura Molecular , Oryza/metabolismo , Espalhamento a Baixo Ângulo , Sementes/química , Amido/metabolismo , Fatores de Tempo , Difração de Raios X
12.
Food Chem ; 294: 248-259, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31126460

RESUMO

In this study, ultrasound was used to modulate the molecular structure of retrograded starch (RS3) responsible for the digestion properties, and the relationships among the ultrasonic power, molecular structure, and RS3 digestibility were revealed. Results revealed that the morphological characteristics of RS3 changed after ultrasonic treatment, and high power resulted in more compact block-shape structure. The results of particle size analysis, Fourier transform infrared spectroscopy, and X-ray diffraction showed that ultrasound decreased the long-range orders but increased the median particle size, short-range orders, and V-type polymorph of ultrasound-treated RS3. A decreased (double helix of amylopectin) and an increased (single helix of V-amylose) enthalpy change were observed by differential scanning calorimeter. Digestion profiles showed that some fractions of rapidly-digestible starch were converted into slowly-digestible starch and/or resistant starch. This study provides a potential approach to regulate the digestion of starch-rich foods with desired digestibility through ultrasonic treatment.


Assuntos
Amido/química , Amilopectina/química , Amilopectina/metabolismo , Amilose/química , Varredura Diferencial de Calorimetria , Conformação Molecular , Tamanho da Partícula , Solubilidade , Sonicação , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/metabolismo , Difração de Raios X , alfa-Amilases/metabolismo
13.
Arch Anim Nutr ; 73(3): 194-207, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30864858

RESUMO

The present study was conducted to investigate the effects of dietary amylose and amylopectin ratio on growth performance, meat quality, postmortem glycolysis and muscle fibre type transformation of finishing pigs. Twenty-four barrows (Duroc × Landrace × Yorkshire) with an average initial body weight of 61.7 ± 2.01 kg were randomly assigned to four dietary treatments with amylose: amylopectin ratios of 1:1 (HD), 1:2 (MD), 1:3 (CD) and 1:4 (LD). The results showed that the average daily weight gain of finishing pigs tended to reduce with the ratio of amylose and amylopectin decreased (p = 0.09). Diet LD increased the pH24h value and decreased the shear force in longissimus dorsi (LM) compared with diet HD (p < 0.05). Diet LD decreased the lactate content and the HK-2 mRNA abundance and increased the mRNA abundance of ATP5B in LM compared with diet HD (p < 0.05). Higher mRNA abundance of MyHC I and lesser abundance of MyHC IIb in LM were found in pigs fed diet CD and LD than those fed diet HD (p < 0.05). Furthermore, pigs fed diet LD had higher mRNA abundances of PGC-1α and PPAR δ in LM than other groups (p < 0.05). These results suggested that diet with low amylose and amylopectin ratio could improve meat quality of finishing pigs via delaying muscle glycolysis capacity and shifting muscle fibre types.


Assuntos
Amilopectina/metabolismo , Amilose/metabolismo , Glicólise/fisiologia , Carne/análise , Fibras Musculares Esqueléticas/fisiologia , Sus scrofa/fisiologia , Amilopectina/administração & dosagem , Amilose/administração & dosagem , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Dieta/veterinária , Relação Dose-Resposta a Droga , Glicólise/efeitos dos fármacos , Masculino , Fibras Musculares Esqueléticas/efeitos dos fármacos , Distribuição Aleatória , Sus scrofa/crescimento & desenvolvimento
14.
Food Chem ; 283: 375-380, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30722886

RESUMO

In the present study, the effects of different irrigation levels (I50: 50%; I75: 75%; and I100: 100% of depleted water from field capacity) and nitrogen fertilizer concentrations (N1:100, N2:200 and N3:300 kg ha-1N) on starch properties (total, resistant and nonresistant starch, amylose-amylopectin ratios) and phytic acid content of maize were investigated. The single and interaction effects of the treatments and also influence of harvesting year were evaluated. Total starch accumulation changed with the treatments and the highest values were obtained from I50 and N3 combination and the lowest levels were recorded for I100-N1 and I100-N2 treatments. Amylopectin increased with the effect of irrigation, while the amylose decreased with the irrigation treatment in parallel to amylopectin content. Besides, the lowest phytic acid level was also obtained from the treatments of I100 and N1. This study would provide some valuable information for agricultural and nutritional applications of maize.


Assuntos
Fertilizantes/análise , Ácido Fítico/análise , Amido/química , Agricultura , Amilopectina/metabolismo , Amilose/metabolismo , Nitrogênio/química , Estações do Ano , Solo/química , Zea mays/química , Zea mays/metabolismo
15.
New Phytol ; 221(1): 356-370, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30055112

RESUMO

The initiation of starch granule formation is still poorly understood. However, the soluble starch synthase 4 (SS4) appears to be a major component of this process since it is required to synthesize the correct number of starch granules in the chloroplasts of Arabidopsis thaliana plants. A yeast two-hybrid screen allowed the identification of several putative SS4 interacting partners. We identified the product of At4g32190 locus as a chloroplast-targeted PROTEIN INVOLVED IN STARCH INITIATION (named PII1). Arabidopsis mutants devoid of PII1 display an alteration of the starch initiation process and accumulate, on average, one starch granule per plastid instead of the five to seven granules found in plastids of wild-type plants. These granules are larger than in wild-type, and they remain flat and lenticular. pii1 mutants display wild-type growth rates and accumulate standard starch amounts. Moreover, starch characteristics, such as amylopectin chain length distribution, remain unchanged. Our results reveal the involvement of PII1 in the starch priming process in Arabidopsis leaves through interaction with SS4.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Ciclo Celular/metabolismo , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Amido/metabolismo , Amilopectina/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Ciclo Celular/genética , Proteínas de Cloroplastos/genética , Cloroplastos/genética , Microscopia Eletrônica de Varredura , Mutação , Cadeias Pesadas de Miosina/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Plastídeos/genética , Plastídeos/metabolismo , Amido/genética , Amido/ultraestrutura , Sintase do Amido/genética , Sintase do Amido/metabolismo
16.
Plant Sci ; 277: 177-187, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30466583

RESUMO

Starches with comb-like profiles have been detected in some cereal endosperms with inhibiting expression of starch branching enzyme (SBE). Although amylose is considered to be an important factor in the formation of the comb-like profile, the details remain unclear. In this study, a transgenic rice line (GLXN-SBEI/IIb-) was derived from japonica waxy rice cultivar Guang-ling-xiang-nuo (GLXN) through antisense RNA inhibition of both SBEI and SBEIIb. The expression and activity of SBEI, SBEIIb and SBEIIa were declined. The GLXN-SBEI/IIb- endosperm contained large and small starch granules, and these starch granules had the comb-like profiles. The comb-like profiles of starches were detected in GLXN-SBEI/IIb- endosperm after 10 days after flowering with gradually increasing proportion of long branch-chains of amylopectin. The long branch-chains of amylopectin were responsible for forming the comb-like profiles at the outer region of starch granules. The gradually decreasing expression of SBEs influenced the synthesis of amylopectin during endosperm development, resulting in different structure between the inner and outer regions of starch granules from GLXN-SBEI/IIb- endosperm. The above results indicated that the long branch-chains of amylopectin, not amylose, led to the formation of comb-like profiles of starch granules in cereal crops with inhibiting expression of SBEs.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Amilopectina/metabolismo , Oryza/enzimologia , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Amido/metabolismo , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Oryza/genética , Proteínas de Plantas/genética
17.
Food Chem ; 259: 89-98, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29680067

RESUMO

Vibrational spectroscopic techniques were employed to predict the mechanism of starch hydrolysis based on structural changes during germination of paddy. The proposed mechanism for starch hydrolysis dealt with the synthesis of amylase at the onset of germination, depicting an increased intensity of spectral bands at amide I, II and III regions. The process commenced with the enzyme actions on skeletal mode of pyranose ring structure of glucose units followed by cleavage of the glycosidic linkage by the process of multiple and multi-chain attack resulting in decrease of the bands (400-900 cm-1). The increased intensity of the bands (1200-1500 cm-1) indicated the process of starch hydrolysis and formation of d-glucose. Multivariate calibration analysis (PCA and PLS) was employed to correlate Raman spectral data with biochemical changes during germination and to develop a calibration model. The model showed a high prediction ability with low root mean square error of prediction (RMSEP) (0.043-0.568).


Assuntos
Oryza/metabolismo , Análise Espectral Raman/métodos , Amido/química , Amilopectina/análise , Amilopectina/metabolismo , Amilose/análise , Amilose/metabolismo , Calibragem , Glucose/metabolismo , Hidrólise , Análise dos Mínimos Quadrados , Análise Multivariada , Análise de Componente Principal , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/metabolismo , Vibração
18.
BMC Plant Biol ; 18(1): 59, 2018 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-29636002

RESUMO

BACKGROUND: Starch is the major component of cereal grains and is composed of essentially linear amylose and highly branched amylopectin. The properties and composition of starch determine the use and value of grains and their products. Starch synthase (SS) I, SSIIa, and SSIIIa play central roles in amylopectin biosynthesis. These three SS isozymes also affect seed development, as complete loss of both SSI and SSIIIa under reduced SSIIa activity in rice lead to sterility, whereas presence of minimal SSI or SSIIIa activity is sufficient for generating fertile seeds. SSs, branching enzymes, and/or debranching enzymes form protein complexes in cereal. However, the relationship between starch properties and the formation of protein complexes remain largely unknown. To better understand this phenomenon, properties of starch and protein complex formation were analyzed using developing mutant rice seeds (ss1 L /ss2a L /ss3a) in which all three major SS activities were reduced. RESULTS: The SS activity of ss1 L /ss2a L /ss3a was 25%-30% that of the wild-type. However, the grain weight of ss1 L /ss2a L /ss3a was 89% of the wild-type, 55% of which was starch, showing considerable starch synthesis. The reduction of soluble SS activity in ss1 L /ss2a L /ss3a resulted in increased levels of ADP-glucose pyrophosphorylase and granule-bound starch synthase I, which are responsible for substrate synthesis and amylose synthesis, respectively. Together, these features led to an increase in apparent amylose content (34%) in ss1 L /ss2a L /ss3a compared with wild-type (20%). Gel filtration chromatography of the soluble proteins in ss1 L /ss2a L /ss3a showed that the majority of the starch biosynthetic enzymes maintained the similar elution patterns as wild-type, except that the amounts of high-molecular-weight SSI (> 300 kDa) were reduced and SSIIa of approximately 200-300 kDa were present instead of those > 440 kDa, which predominate in wild-type. Immuno-precipitation analyses suggested that the interaction between the starch biosynthetic enzymes maybe reduced or weaker than in wild-type. CONCLUSIONS: Although major SS isozymes were simultaneously reduced in ss1 L /ss2a L /ss3a rice, active protein complexes were formed with a slightly altered pattern, suggesting that the assembly of protein complexes may be complemented among the SS isozymes. In addition, ss1 L /ss2a L /ss3a maintained the ability to synthesize starch and accumulated less amylopectin and more amylose in starch.


Assuntos
Oryza/enzimologia , Oryza/metabolismo , Sementes/enzimologia , Sementes/metabolismo , Sintase do Amido/metabolismo , Amido/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo
19.
Sci Rep ; 8(1): 4548, 2018 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-29540822

RESUMO

Waxy wheat has unique end-use properties; however, its production is limited due mainly to its low grain yield compared with non-waxy wheat. In order to increase its grain yield, it is critical to understand the eco-physiological differences in grain filling between the waxy and non-waxy wheat. In this study, two waxy wheat and two non-waxy wheat cultivars were used to investigate the differences in starch-associated enzymes processes, sucrose and starch dynamics, yield components, and the final grain yield. The results indicated that the mean total grain starch and amylose content, the average 1000-kernel weight and grain yield of the waxy wheat were lower than those of the non-waxy wheat at maturity. The amylose content was significantly and positively correlated with the activity of GBSS (r = 0.80, p < 0.01). Significant positive correlation also exists among activities of AGPase, SSS, GBSS, and SBE, except for GBSS-SBE. In summary, our study has revealed that the reduced conversion of sucrose to starch in the late grain filling stage is the main cause for the low kernel weight and total starch accumulation of the waxy wheat. The reduced conversion also appears to be a factor contributing to the lower grain yield of the waxy wheat.


Assuntos
Grão Comestível/crescimento & desenvolvimento , Sintase do Amido/metabolismo , Amido/metabolismo , Triticum/crescimento & desenvolvimento , Amilopectina/metabolismo , Amilose/metabolismo , Biomassa , Grão Comestível/enzimologia , Grão Comestível/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/metabolismo , Triticum/enzimologia , Triticum/metabolismo , Ceras
20.
BMC Plant Biol ; 18(1): 9, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29310584

RESUMO

BACKGROUND: Endosperm starch provides prime energy for cereal seedling growth. Cereal endosperm with repression of starch branching enzyme (SBE) has been widely studied for its high resistant starch content and health benefit. However, in barley and maize, the repression of SBE changes starch component and amylopectin structure which affects grain germination and seedling establishment. A high resistant starch rice line (TRS) has been developed through inhibiting SBEI/IIb, and its starch has very high resistance to in vitro hydrolysis and digestion. However, it is unclear whether the starch resists in situ degradation in seed and influences seedling growth after grain germination. RESULTS: In this study, TRS and its wild-type rice cultivar Te-qing (TQ) were used to investigate the seedling growth, starch property changes, and in situ starch degradation during seedling growth. The slow degradation of starch in TRS seed restrained the seedling growth. The starch components including amylose and amylopectin were simultaneously degraded in TQ seeds during seedling growth, but in TRS seeds, the amylose was degraded faster than amylopectin and the amylopectin long branch-chains with B-type crystallinity had high resistance to in situ degradation. TQ starch was gradually degraded from the proximal to distal region of embryo and from the outer to inner in endosperm. However, TRS endosperm contained polygonal, aggregate, elongated and hollow starch from inner to outer. The polygonal starch similar to TQ starch was completely degraded, and the other starches with long branch-chains of amylopectin and B-type crystallinity were degraded faster at the early stage of seedling growth but had high resistance to in situ degradation during TRS seedling growth. CONCLUSIONS: The B-type crystallinity and long branch-chains of amylopectin in TRS seed had high resistance to in situ degradation, which inhibited TRS seedling growth.


Assuntos
Amilopectina/metabolismo , Oryza/metabolismo , Plântula/metabolismo , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Oryza/genética , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/crescimento & desenvolvimento
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