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1.
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
2.
Prep Biochem Biotechnol ; 50(2): 172-180, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31846387

RESUMO

The ß-amylase was encapsulated in emulsion liquid membrane (ELM), which acted as a reactor for conversion of starch to maltose. The membrane phase was consisted of surfactant (span 80), stabilizer (polystyrene), carrier for maltose transport (methyl cholate) and solvent (xylene). The substrate starch in feed phase entered into the internal phase by the process of diffusion and hydrolyzed to maltose by encapsulated ß-amylase. Methyl cholate present in the membrane acts as a carrier for the product maltose, which helps in transport of maltose to feed phase from internal aqueous phase. The residual activity of ß-amylase after the five-reaction cycle was found to decrease to ∼70%, which indicated possibility to recycle the components of the emulsion and enzyme. The pH and temperature of the encapsulated enzyme were found to be optimum at 5.5 and 60 °C, respectively. The novelty of the present work lies in the development of Enzyme Emulsion Liquid Membranes (EELM) bioreactor for the hydrolysis of starch into maltose mediated by encapsulated ß-amylase. The attempt has been made for the first time for the successful encapsulation of ß-amylase into EELM. The best results gave the highest residual enzyme activity (94.1%) and maltose production (29.13 mg/mL).


Assuntos
Reatores Biológicos , Maltose/metabolismo , Amido/metabolismo , beta-Amilase/metabolismo , Óleos/química , Água/química
3.
Int J Biol Macromol ; 144: 170-182, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31843605

RESUMO

ß-Amylase was immobilized onto GQDs using 3-aminopropyltriethoxysilane and glutaraldehyde. Optimization was carried out by Box-Behnken design and binding was confirmed by SEM, AFM, FTIR and fluorescence microscopy. Predicted optimum immobilization efficiency (88.64%) was very close to actual (87.98%), which confirmed the success of the immobilization process. The immobilized enzyme showed maximum activity at pH 5.0 and 57 °C, whereas Km and Vmax were found to be 6.40 mg/mL and 714.28 µmol/min/mg, respectively. The enzyme retained 75% activity after 12 uses at 30 °C. Increased values of ΔG° ΔH°, half-life and activation energy of the enzyme inactivation (ΔEd) revealed that thermo-stability increases after immobilization and the process followed first-order kinetics (r2 > 0.96). The activation energy of catalysis (ΔEa) and ΔEd for immobilized enzyme were 22.58 and 158.99 ± 1.10 kJ/mol, respectively which revealed that denaturation of the enzyme requires a higher amount of energy rather than catalysis. Thermodynamic and fluorescence spectroscopic studies revealed that the process is non-spontaneous (ΔG > 0) and endothermic (ΔH > 0) and occurred through protein unfolding rather than aggregation (ΔS > 0). Thus increase in thermo-stability of immobilized fenugreek ß-amylase and non-toxic nature of GQDs could be exploited for maltose production in beverage, food and pharmaceutical industries.


Assuntos
Enzimas Imobilizadas/metabolismo , Grafite/química , Pontos Quânticos/química , Trigonella/enzimologia , beta-Amilase/metabolismo , Estabilidade Enzimática , Germinação , Concentração de Íons de Hidrogênio , Cinética , Pontos Quânticos/ultraestrutura , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
4.
Colloids Surf B Biointerfaces ; 185: 110600, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31704608

RESUMO

In this communication, fenugreek ß-amylase was immobilized onto functionalized tungsten disulfide nanoparticles through cross-linker glutaraldehyde and successful immobilization was confirmed by SEM, AFM and FTIR spectroscopy. To make the process economical and efficient, optimization of independent variables was carried out using Box-Behnken design of response surface methodology. Approximately similar predicted (85.6%) and experimental (84.2%) immobilization efficiency revealed that the model is suitable for design of space. Optimum temperature was calculated to be 60 °C. After immobilization, an increased Km (2.12 times) and a decreased Vmax (0.58 times), indicated inaccessibility of active site residues to the substrate. The immobilized enzyme retained 77% relative activity after 10 uses whereas 40% residual activity was obtained after 120 days. An increased half-life with concomitantly decreased kinetic rate constant revealed that the immobilized enzyme is more stable at a higher temperature and the process followed first-order kinetics (R2 > 0.93). The limit of detection for maltose and sucrose fluorescence biosensor was found to be 0.052 and 0.096 mM, respectively. Thermodynamic parameters such as changes in Gibbs free energy (ΔG < 0), enthalpy (ΔH > 0) and entropy (ΔS >0) revealed that the process is spontaneous and endothermic, driven by hydrophobic interactions. Thermo-stability data at higher temperature for the immobilized enzyme makes it a suitable candidate for industrial applications in the production of maltose in food and pharmaceutical industries. Furthermore, fluorescence biosensor could be used to detect and quantify maltose and sucrose to maintain the quality of industrial products.


Assuntos
Dissulfetos/química , Enzimas Imobilizadas/metabolismo , Maltose/metabolismo , Nanopartículas/química , Sacarose/metabolismo , Trigonella/enzimologia , Compostos de Tungstênio/química , beta-Amilase/metabolismo , Estabilidade Enzimática , Enzimas Imobilizadas/química , Concentração de Íons de Hidrogênio , Cinética , Maltose/química , Sacarose/química , Temperatura , Termodinâmica , beta-Amilase/química
5.
Appl Microbiol Biotechnol ; 103(21-22): 9169-9180, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31673743

RESUMO

Pseudomonas stutzeri strain XL-2 exhibited significant performance on biofilm formation. Extracellular polymeric substances (EPS) secreted by strain XL-2 were characterized by colorimetry and Fourier transform infrared (FT-IR) spectroscopy. The biofilm growth showed a strong positive correlation (rP=0.96, P<0.01) to extracellular protein content, but no correlation to exopolysaccharide content. Hydrolyzing the biofilm with proteinase K caused a significant decrease in biofilm growth (t=3.7, P<0.05), whereas the changes in biofilm growth were not significant when the biofilm was hydrolyzed by α-amylase and ß-amylase, implying that proteins rather than polysaccharides played the dominant role in biofilm formation. More specifically, confocal laser scanning microscopy (CLSM) revealed that the extracellular proteins were tightly bound to the cells, resulting in the cells with EPS presenting more biofilm promotion protein secondary structures, such as three-turn helices, ß-sheet, and α-helices, than cells without EPS. Both bio-assays and quantitative analysis demonstrated that strain XL-2 produced signal molecules of N-acylhomoserine lactones (AHLs) during biofilm formation process. The concentrations of C6-HLS and C6-oxo-HLS were both significantly positively correlated with protein contents (P<0.05). Dosing exogenous C6-HLS and C6-oxo-HLS also resulted in the increase in protein content. Therefore, it was speculated that C6-HLS and C6-oxo-HLS released by strain XL-2 could up-regulate the secretion of proteins in EPS, and thus promote the formation of biofilm.


Assuntos
Biofilmes/crescimento & desenvolvimento , Matriz Extracelular de Substâncias Poliméricas/microbiologia , Pseudomonas stutzeri/crescimento & desenvolvimento , Pseudomonas stutzeri/metabolismo , Acil-Butirolactonas/metabolismo , Microscopia Confocal , Espectroscopia de Infravermelho com Transformada de Fourier , alfa-Amilases/metabolismo , beta-Amilase/metabolismo
6.
Plant Sci ; 287: 110184, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31481191

RESUMO

ß-Amylase (BAM) is involved in sugar metabolism, but the role of BAM genes in cold tolerance remains poorly understood. Here, we report the identification and functional characterization of the chloroplast-localized BAM-encoding gene PbrBAM3 isolated from Pyrus betulaefolia. The transcript levels of PbrBAM3 were up-regulated under cold, dehydration and ABA, but repressed by maltose. Overexpression of PbrBAM3 in tobacco (Nicotiana tabacum) and pear (P. ussuriensis) conferred increased BAM activity, promoted starch degradation after chilling treatments and enhanced tolerance to cold. Under the chilling stress, the transgenic tobacco and P. ussuriensis exhibited lessened reactive oxygen species (ROS) generation, higher levels of antioxidant enzymes activity, and greater accumulation of soluble sugars (specially maltose) than the corresponding wild type plants. Taken together, these results demonstrate that PbrBAM3 plays an important role in cold tolerance, at least in part, by raising the levels of soluble sugars capable of acting as osmolytes or antioxidants.


Assuntos
Regulação da Expressão Gênica de Plantas , Pyrus/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Açúcares/metabolismo , beta-Amilase/metabolismo , Temperatura Baixa , Resposta ao Choque Frio , Homeostase , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pyrus/genética , Pyrus/fisiologia , Estresse Fisiológico , beta-Amilase/genética
7.
Sci Rep ; 9(1): 9602, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31270378

RESUMO

In olive trees, Xylella fastidiosa colonizes xylem vessels and compromises water transport causing the olive quick decline syndrome (OQDS). The loss of hydraulic conductivity could be attributed to vessel occlusions induced both by the bacteria biofilm and by plant responses (tyloses, gums, etc.) that could trigger embolism. The ability of the infected plants to detect embolism and to respond, by activating mechanisms to restore the hydraulic conductivity, can influence the severity of the disease symptomatology. In order to investigate these mechanisms in the X. fastidiosa-resistant olive cultivar Leccino and in the susceptible Cellina di Nardò, sections of healthy olive stems were analysed by laser scanning microscope to calculate the cavitation vulnerability index. Findings indicated that the cultivar Leccino seems to be constitutively less susceptible to cavitation than the susceptible one. Among the vascular refilling mechanisms, starch hydrolysis is a well-known strategy to refill xylem vessels that suffered cavitation and it is characterized by a dense accumulation of starch grains in the xylem parenchima; SEM-EDX analysis of stem cross-sections of infected plants revealed an aggregation of starch grains in the Leccino xylem vessels. These observations could indicate that this cultivar, as well as being anatomically less susceptible to cavitation, it also could be able to activate more efficient refilling mechanisms, restoring vessel's hydraulic conductivity. In order to verify this hypothesis, we analysed the expression levels of some genes belonging to families involved in embolism sensing and refilling mechanisms: aquaporins, sucrose transporters, carbohydrate metabolism and enzymes related to starch breakdown, alpha and beta-amylase. The obtained genes expression patterns suggested that the infected plants of the cultivar Leccino strongly modulates the genes involved in embolism sensing and refilling.


Assuntos
Olea/metabolismo , Xylella/fisiologia , Xilema/fisiologia , Aquaporinas/metabolismo , Suscetibilidade a Doenças , Microscopia Eletrônica de Varredura , Olea/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Caules de Planta/metabolismo , Amido/metabolismo , Xilema/anatomia & histologia , beta-Amilase/metabolismo
8.
Plant Cell ; 31(9): 2169-2186, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31266901

RESUMO

In Arabidopsis (Arabidopsis thaliana) leaves, starch is synthesized during the day and degraded at night to fuel growth and metabolism. Starch is degraded primarily by ß-amylases, liberating maltose, but this activity is preceded by glucan phosphorylation and is accompanied by dephosphorylation. A glucan phosphatase family member, LIKE SEX4 1 (LSF1), binds starch and is required for normal starch degradation, but its exact role is unclear. Here, we show that LSF1 does not dephosphorylate glucans. The recombinant dual specificity phosphatase (DSP) domain of LSF1 had no detectable phosphatase activity. Furthermore, a variant of LSF1 mutated in the catalytic cysteine of the DSP domain complemented the starch-excess phenotype of the lsf1 mutant. By contrast, a variant of LSF1 with mutations in the carbohydrate binding module did not complement lsf1 Thus, glucan binding, but not phosphatase activity, is required for the function of LSF1 in starch degradation. LSF1 interacts with the ß-amylases BAM1 and BAM3, and the BAM1-LSF1 complex shows amylolytic but not glucan phosphatase activity. Nighttime maltose levels are reduced in lsf1, and genetic analysis indicated that the starch-excess phenotype of lsf1 is dependent on bam1 and bam3 We propose that LSF1 binds ß-amylases at the starch granule surface, thereby promoting starch degradation.


Assuntos
Arabidopsis/metabolismo , Metabolismo dos Carboidratos/fisiologia , Fosfatases de Especificidade Dupla/metabolismo , Amido/metabolismo , beta-Amilase/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Metabolismo dos Carboidratos/genética , Proteínas de Transporte , Clonagem Molecular , Fosfatases de Especificidade Dupla/genética , Regulação da Expressão Gênica de Plantas , Glucanos/metabolismo , Fosforilação , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , Domínios e Motivos de Interação entre Proteínas , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes , Alinhamento de Sequência , Tabaco/genética , Tabaco/metabolismo , beta-Amilase/genética
9.
Food Chem ; 297: 124991, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253316

RESUMO

Plant species differ greatly in their ability to acclimatise to and survive, cold stress. Normally, potato tubers are stored at low temperatures (below 10 °C) to delay sprouting. In this research, combined transcriptomic and proteomic analysis was conducted on potato tubers stored at 15 °C, 4 °C and 0 °C to investigate the mechanism of cold responses during postharvest storage. Results showed that soluble sugars were accumulated under low temperatures, regulating by granule-bound starch synthase 1, beta-amylase, invertase inhibitor and fructokinase. In addition, fifteen heat shock proteins (Hsps), including three Hsp70s, two Hsp80s, one Hsp90, one Hsp100 and eight small Hsps, were induced by low temperatures, which may act individually or synergistically to prevent physiological or cellular damage from cold stress in postharvest potato tubers. This research provided general information of sugar accumulation and defense response in potato tuber under cold storage.


Assuntos
Proteínas de Choque Térmico/metabolismo , Proteínas de Plantas/metabolismo , Solanum tuberosum/metabolismo , Açúcares/metabolismo , Transcriptoma , Temperatura Baixa , Armazenamento de Alimentos , Tubérculos/genética , Tubérculos/metabolismo , Proteômica , Solanum tuberosum/genética , Sintase do Amido/metabolismo , beta-Amilase/metabolismo
10.
Int J Biol Macromol ; 136: 1228-1236, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31228499

RESUMO

It is highly desirable to lower the glycemic index of rice starch-based foods. Herein, rice starch granules were treated sequentially with ß-amylase (BA), transglucosidase (TG) and pullulanase (PUL). The results indicated that compared with native rice starch and PUL-modified starch, degree of crystallinity, gelatinization temperature and enthalpy of BA/TG/PUL-modified starches increased remarkably. Moreover, the functionality of BA/TG/PUL-treated starch depended enormously on TG treatment time. BA/TG/PUL-modified starch possessed the highest relative crystallinity, gelatinization temperatures and gelatinization enthalpy and the content of resistant starch at TG treatment time of 20 h and the resistant crystals were formed largely from linear chains with DP 9-11. Whether before cooking or after cooking, BA/TG/PUL-modified starches had strong resistance to enzyme hydrolysis and had lower glycemic index. This outcome may offer a novel sight for the exploitation of starch-based functional foods with low glycemic index.


Assuntos
Digestão , Glucosiltransferases/metabolismo , Glicosídeo Hidrolases/metabolismo , Oryza/química , Amido/química , Amido/metabolismo , beta-Amilase/metabolismo , Amilose/análise , Aspergillus niger/enzimologia , Bacillales/enzimologia , Culinária , Índice Glicêmico , Hidrólise , Pseudomonas/enzimologia
11.
Food Chem ; 289: 103-111, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30955591

RESUMO

The effect of three combinations of bioprocessing methods by lactic acid fermentation, cell wall hydrolyzing enzymes and phytase on the biochemical (protein, fat, carbohydrate composition) and technofunctional properties (protein solubility, emulsifying and foaming properties) of wheat bran protein isolates were evaluated. The bioprocessing increased the protein (up to 80%) and fat content (up to 22.8%) in the isolates due to the degradation of starch and soluble pentosans. Additional proteins, globulin 3A and 3C, chitinase, ß-amylase and LMW glutenins, were identified from the electrophoretic pattern of the protein isolate bioprocessed with added enzymes. Generally, the bioprocessed protein isolate had lower protein solubility and stronger net charge in pH below 7, when compared to the protein isolate made without bioprocessing. The emulsifying properties of the protein isolates were not affected by bioprocessing. However, the foaming stability of the protein isolates was nearly doubled by bioprocessing with cell wall hydrolyzing enzymes and phytase.


Assuntos
Fibras na Dieta/metabolismo , Proteínas de Plantas/química , Quitinases/química , Quitinases/isolamento & purificação , Quitinases/metabolismo , Eletroforese em Gel de Poliacrilamida , Hidrólise , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Estabilidade Proteica , Solubilidade , Amido/metabolismo , beta-Amilase/química , beta-Amilase/isolamento & purificação , beta-Amilase/metabolismo
12.
Planta ; 250(1): 281-298, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31025197

RESUMO

MAIN CONCLUSION: The alpha-amylase and beta-amylase genes have been identified from tea plants, and their bioinformatic characteristics and expression patterns provide a foundation for further studies to elucidate their biological functions. Alpha-amylase (AMY)- and beta-amylase (BAM)-mediated starch degradation plays central roles in carbohydrate metabolism and participates extensively in the regulation of a wide range of biological processes, including growth, development and stress response. However, the AMY and BAM genes in tea plants (Camellia sinensis) are poorly understood, and the biological functions of these genes remain to be elucidated. In this study, three CsAMY and nine CsBAM genes from tea plants were identified based on genomic and transcriptomic database analyses, and the genes were subjected to comprehensive bioinformatic characterization. Phylogenetic analysis showed that the CsAMY proteins could be clustered into three different subfamilies, and nine CsBAM proteins could be classified into four groups. Putative catalytically active proteins were identified based on multiple sequence alignments, and the tertiary structures of these proteins were analyzed. Cis-element analysis indicated that CsAMY and CsBAM were extensively involved in tea plant growth, development and stress response. In addition, the CsAMY and CsBAM genes were differentially expressed in various tissues and were regulated by stress treatments (e.g., ABA, cold, drought and salt stress), and the expression patterns of these genes were associated with the postharvest withering and rotation processes. Taken together, our results will enhance the understanding of the roles of the CsAMY and CsBAM gene families in the growth, development and stress response of tea plants and of the potential functions of these genes in determining tea quality during the postharvest processing of tea leaves.


Assuntos
Camellia sinensis/enzimologia , Regulação da Expressão Gênica de Plantas , alfa-Amilases/metabolismo , beta-Amilase/metabolismo , Camellia sinensis/genética , Camellia sinensis/fisiologia , Secas , Perfilação da Expressão Gênica , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Alinhamento de Sequência , Estresse Fisiológico , alfa-Amilases/genética , beta-Amilase/genética
13.
Biochem Biophys Res Commun ; 514(1): 301-307, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31030939

RESUMO

OBJECTIVE: To simultaneously increase the thermostability and catalytic activity of barley ß-amylase. METHODS: The amino acid sequences of various barley ß-amylases with different enzyme properties were aligned, two amino acid residues R115 and T387 were identified to be important for barley ß-amylase properties. R115C and T387V were then generated using site-directed and saturation mutagenesis. RESULTS: R115C and T387V mutants increased the enzyme catalytic activity and thermostability, respectively. After combinational mutagenesis, the T50 value and t(1/2,60oC) value of R115C/T387V mutant reached 59.4 °C and 48.8 min, which were 3.6 °C higher and 29.5 min longer than those of wild-type. The kcat/Km value of mutant R115C/T387V were 59.82/s·mM, which were 54.7% higher than that of wild-type. The increased surface hydrophobicity and newly formed strong hydrogen bonds and salt bridges might be responsible for the enzyme thermostability improvement while the two additional hydrogen bonds formed in the active center may lead to the catalytic property enhancement. CONCLUSIONS: The mutant R115C/T387V showed high catalytic activity and thermostability indicating great potential for application in industry.


Assuntos
Substituição de Aminoácidos , Hordeum/enzimologia , beta-Amilase/química , beta-Amilase/genética , beta-Amilase/metabolismo , Arginina/genética , Estabilidade Enzimática , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Conformação Proteica , Engenharia de Proteínas , Alinhamento de Sequência , Treonina/genética
14.
Prep Biochem Biotechnol ; 49(1): 88-94, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30636502

RESUMO

In this study, the effects of carbon source, nitrogen source, and metal ions on cell growth and Bacillus aryabhattai ß-amylase production in recombinant Brevibacillus choshinensis were investigated. The optimal medium for ß-amylase production, containing glucose (7.5 g·L-1), pig bone peptone (40.0 g·L-1), Mg2+ (0.05 mol·L-1), and trace metal elements, was determined through single-factor experiments in shake flasks. When cultured in the optimized medium, the ß-amylase yield reached 925.4 U mL-1, which was 7.2-fold higher than that obtained in the initial medium. Besides, a modified feeding strategy was proposed and applied in a 3-L fermentor fed with glucose, which achieved a dry cell weight of 15.4 g L-1. Through this cultivation approached 30 °C with 0 g·L-1 initial glucose concentration, the maximum ß-amylase activity reached 5371.8 U mL-1, which was 41.7-fold higher than that obtained with the initial medium in shake flask.


Assuntos
Bacillus/genética , beta-Amilase/biossíntese , Biomassa , Carbono/metabolismo , Meios de Cultura , Eletroforese em Gel de Poliacrilamida , Fermentação , Glucose/metabolismo , Metais/metabolismo , Nitrogênio/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Temperatura , beta-Amilase/genética , beta-Amilase/metabolismo
15.
Gene ; 693: 127-136, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-30594635

RESUMO

Expression of hordeins and ß-amylase during barley grain development is important in determining malting quality parameters that are controlled by protein and malt enzyme levels. The relationship between protein and enzyme levels is confounding because, in general, protein and malt enzyme activity are positively correlated and the malting and brewing industries demand relatively low levels of protein and relatively high levels of enzymes. Separation of these traits is desirable because high protein levels are one of the primary causes of barley not meeting malt quality standards. Studies on barley grain development have not resulted in a consensus on the temporal accumulation of hordein and endosperm-specific ß-amylase (Bmy1) and thus, it is unclear whether hordeins and Bmy1 are under control of the same temporal regulator (s). Therefore, temporal expression patterns of hordeins (B- [Hor2], C- [Hor1], D- [Hor3], and γ-hordein [Hor5]) were compared to Bmy1 throughout grain development (5 to 35 days after anthesis (DAA)). Transcript accumulation between hordeins and Bmy1 occurred simultaneously beginning during the pre-storage phase of grain development whereas the B1-hordein protein appeared two days before Bmy1 most likely due to variations in gene copy number. Interestingly, the largest increase in hordein and Bmy1 transcript levels occurred between 5 and 9 (Hor2, Hor2-B1, Hor2-B3, Hor3, Hor5-γ1, and Hor5-γ3) or 9 and 13 DAA (Hor1 and Bmy1). Additionally, ubiquitous ß-amylase (Bmy2) has a novel expression pattern and was the predominant ß-amylase present between 5 and 15 DAA whereas Bmy1 was the predominant ß-amylase present between 17 and 35 DAA.


Assuntos
Glutens/genética , Hordeum/genética , beta-Amilase/genética , Grão Comestível/genética , Expressão Gênica/genética , Regulação da Expressão Gênica de Plantas/genética , Genes de Plantas , Glutens/metabolismo , Proteínas de Plantas/genética , RNA Mensageiro/genética , Sementes/genética , Transcriptoma/genética , beta-Amilase/metabolismo
16.
Food Chem ; 276: 583-590, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30409636

RESUMO

The present work describes efficient hydrolysis of native starch by a novel ß-amylase from peanut (Arachis hypogaea). The Dextrose Equivalent value, which is a measure of starch hydrolysis, for potato and corn starch increased significantly by 40% and 10%, respectively, releasing maltose. Scanning electron microscopy revealed that enzymatic corrosion occurred mainly at the surface of starch granules, leaving broken granules to smaller particles at later stage of digestion. Further, X-ray analysis and Fourier transform infrared spectroscopy displayed the loss of ordered structure in the enzyme degraded starches. These results described the pattern of hydrolysis. Since the action of already known plant ß-amylases (sweet potato and soybean) on native starch granule is not very effective and requires gelatinization for maltose production, ß-amylase from peanut could be a useful alternative in the present endeavor. It would potentially save time and money arising from gelatinization and lead to improvements in industrial maltose production.


Assuntos
Arachis/enzimologia , Amido/química , beta-Amilase/metabolismo , Hidrólise , Maltose/química
17.
Food Chem ; 277: 504-514, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30502177

RESUMO

Sweet potato starch products possess unacceptable hardness and poor transparency that in-turn reduces consumer acceptability. To expand the sweet potato starch utility with user acceptable and palatable food products herein enzyme modification has been carried out. Transglucosidase (TGAN) in combination with maltogenic α-amylase (MABS) and ß-amylase (BA) appears to be advantageous to modulate sweet potato starch properties. The MABS → BA → TGAN treatment increases the α-1, 6 glycosidic linkage ratio and short chain proportions (DP ≤ 24). Decrease in chain length, molecular weight and long chain proportions (DP > 24) is noticed. The initial C-type starch polymorphic structure transforms to B-type structure along with decreased crystallinity. Solubility increases substantially with concomitant decrease in viscosity, gelatinization temperature and melting enthalpy. The outcome is believed to open new pathways for regulating the physicochemical properties of sweet potato starch especially by enzyme modification to the design and development of novel sweet potato starch-based products.


Assuntos
Fenômenos Químicos , Manipulação de Alimentos , Ipomoea batatas/química , Ipomoea batatas/enzimologia , Amido/química , Amilose/análise , Varredura Diferencial de Calorimetria , Hidrodinâmica , Microscopia Eletrônica de Varredura , Estrutura Molecular , Peso Molecular , Reologia , Termodinâmica , Viscosidade , Difração de Raios X , alfa-Amilases/metabolismo , beta-Amilase/metabolismo
18.
Plant Sci ; 276: 163-170, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30348315

RESUMO

Multi-gene families present a rich research area to study how related proteins evolve to acquire new structures and functions. The ß-amylase (BAM) gene family is named for catalytic members' ability to hydrolyze starch into maltose units. However, the family also contains proteins that are catalytically inactive, have additional domains, or are not localized with a starch substrate. Here we review the current knowledge of each of the nine Arabidopsis BAMs, including information on their localization, structural features, expression patterns, regulation and potential functions. We also discuss unique characteristics of studying multi-gene families, such as the consideration of different kinetic parameters when performing assays on leaf extracts, and suggest approaches that may be fruitful in learning more about their unique functions.


Assuntos
Arabidopsis/enzimologia , Variação Genética , Família Multigênica , beta-Amilase , Arabidopsis/genética , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Hidrólise , Maltose/metabolismo , Modelos Estruturais , Amido/metabolismo , beta-Amilase/química , beta-Amilase/genética , beta-Amilase/metabolismo
19.
Molecules ; 23(11)2018 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-30356009

RESUMO

The sweet potato ß-amylase (SPA) was modified by 6 types of methoxy polyethylene glycol to enhance its specific activity and thermal stability. The aims of the study were to select the optimum modifier, optimize the modification parameters, and further investigate the characterization of the modified SPA. The results showed that methoxy polyethylene glycol maleimide (molecular weight 5000, Mal-mPEG5000) was the optimum modifier of SPA; Under the optimal modification conditions, the specific activity of Mal-mPEG5000-SPA was 24.06% higher than that of the untreated SPA. Mal-mPEG5000-SPA was monomeric with a molecular weight of about 67 kDa by SDS-PAGE. The characteristics of Mal-mPEG5000-SPA were significantly improved. The Km value, Vmax and Ea in Mal-mPEG5000-SPA for sweet potato starch showed that Mal-mPEG5000-SPA had greater affinity for sweet potato starch and higher speed of hydrolysis than SPA. There was no significant difference of the metal ions' effect on Mal-mPEG5000-SPA and SPA.


Assuntos
Ipomoea batatas/enzimologia , Polietilenoglicóis/química , beta-Amilase/química , Análise de Variância , Ativação Enzimática , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Íons/química , Cinética , Metais/química , Peso Molecular , Relação Estrutura-Atividade , Temperatura , beta-Amilase/metabolismo
20.
Plant Physiol Biochem ; 133: 1-10, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30368115

RESUMO

GA is important for rice seed germination, and seed embryo growth relies on sugar supplementation via starch hydrolysis in the endosperm. Low temperature reduces the seed germination rates of rice; however, the mechanism of GA metabolism and its impact on sugar utilization of germinating seeds under low temperature conditions remain poorly understood. In this study, low-temperature (15 °C) treatment delayed rice (Oryza sativa L.) seed germination, promoted GA deactivation, inhibited GA signal transduction, and increased ABA synthesis in the seed compared with normal treatment (30 °C). Under low temperature conditions, the soluble sugar content in endosperm was reduced along with depression of the specific activity levels of α-amylase (EC 3.2.1.1) and ß-amylase (EC 3.2.1.2), but the soluble sugar content was increased in the embryo compared with the control treatment. Low temperature treatment promoted sugar transportation from endosperm to embryo and reduced the activity levels of enzymes involved in glycolysis and the tricarboxylic acid cycle, which participated in sugar consumption. Exogenous GA3 application (10 µM) prompted GA signal transduction and inhibited ABA synthesis, while enhancing starch hydrolysis and sugar consumption to boost rice seed germination under low temperature conditions. In conclusion, a deficiency of bioactive GAs in rice seeds exposed to low temperature led to a decrement in starch hydrolysis and sugar consumption, thus inhibit seed germination.


Assuntos
Temperatura Baixa , Germinação/fisiologia , Giberelinas/metabolismo , Glicólise/fisiologia , Oryza/metabolismo , Sementes/metabolismo , Ciclo do Ácido Cítrico/fisiologia , alfa-Amilases/metabolismo , beta-Amilase/metabolismo
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