Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.117
Filtrar
1.
PLoS One ; 15(8): e0238307, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853281

RESUMO

OBJECTIVE: Auricular stimulation (AS) is a promising method in the treatment of situational anxiety. Expressive writing (EW) is an established psychological method, which reduces test anxiety and improves exam results. The aim of this crossover trial was to compare AS with EW, and with the no intervention (NI) condition, for treatment of exam anxiety. METHODS: Healthy medical students underwent 3 comparable anatomy exams with an interval of one month, either performing EW, receiving AS or NI prior to the exam; the order of interventions was randomized. AS was applied using indwelling fixed needles bilaterally at the areas innervated mostly by the auricular branch of the vagal nerve on the day before the exam. Anxiety level, measured using State-Trait-Anxiety Inventory (STAI) before and after the interventions and immediately before exam, was the primary outcome. Quality of night sleep, blood pressure, heart rate and activity of salivary alpha-amylase (sAA) were analyzed across 3 conditions. RESULTS: All 37 included participants completed the study. Anxiety level (STAI) decreased immediately after AS in comparison with baseline (P = 0.02) and remained lower in comparison with that after EW and NI (P<0.01) on the day of exam. After EW and NI anxiety increased on the day of exam in comparison with baseline (P<0.01). Quality of sleep improved after AS in comparison with both control conditions (P<0.01). The activity of sAA decreased after EW and after AS (P<0.05) but not after NI condition. CONCLUSION: Auricular stimulation, but not expressive writing, reduced exam anxiety and improved quality of sleep in medical students. These changes might be due to reduced activity of the sympathetic nervous system.


Assuntos
Desempenho Acadêmico/psicologia , Transtornos de Ansiedade/prevenção & controle , Transtornos de Ansiedade/psicologia , Ansiedade/psicologia , Estudantes de Medicina/psicologia , Adolescente , Adulto , Ansiedade/metabolismo , Transtornos de Ansiedade/metabolismo , Pressão Sanguínea/fisiologia , Estudos Cross-Over , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Redação , Adulto Jovem , alfa-Amilases/metabolismo
2.
PLoS One ; 15(8): e0237844, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32834013

RESUMO

The feasibility of the production of germinated rice extracts using indigenous rice from Southern Thailand, including Khemtong (KHT) and Khai Mod Rin (KMR) from a single location at the Pak Phanang River Basin in Nakhon Si Thammarat, was investigated. The nutritional composition and bioactivity of the germinated rice extracts from both cultivars were evaluated. Optimum germination time for both rices was 96 h, leading to the highest GABA, thiamine, free amino acid, total sugar, and α-amylase activity (p<0.05). Germinated KHT had a higher α-amylase activity than germinated KMR at all germination times. Mashing at 60°C/pH 5.5 rendered the extract with the highest GABA content (p<0.05) and desirable contents of other nutrients. In comparison with germinated Sungyod (local colored rice) and Jasmine (commercial Thai rice) extracts, KHT and KMR showed a higher scavenging activity against DPPH•, OH•, and H2O2 (p<0.05) with a comparable ABTS•+ inhibition. For metal chelation, reducing power and ACE inhibitory activity, the germinated Sungyod extract was greater than KHT/KMR. The results demonstrated the potential use of germinated local Thai rice for the production of functional beverages.


Assuntos
Germinação , Fenômenos Fisiológicos da Nutrição , Oryza/química , Oryza/crescimento & desenvolvimento , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Aminoácidos/análise , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Antioxidantes/farmacologia , Compostos de Bifenilo/química , Estudos de Viabilidade , Flavonoides/análise , Depuradores de Radicais Livres/química , Minerais/análise , Fenóis/análise , Ácido Fítico/análise , Picratos/química , Açúcares/análise , Tiamina/análise , Fatores de Tempo , alfa-Amilases/metabolismo , Ácido gama-Aminobutírico/análise
3.
PLoS One ; 15(8): e0236669, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32750092

RESUMO

This study examined the effect of a competitive season on salivary responses [cortisol (sC), testosterone (sT), Testosterone/Cortisol ratio (sT/C), Immunoglobulin A (sIgA), sIgA secretion rate (srIgA), alpha-amylase (sAA)] and upper respiratory symptoms (URS) occurrence in three teams of male soccer players (Under-15, Under-17 and Under-19 yrs.). Training and competition volumes, salivary biomarkers and URS were determined monthly. No differences were found for monthly training volume between teams. Incidence of URS was higher for the U15 (44.9% of the total cases). Higher sT and srIgA were observed for the U19, lower sC were found for the U17 and sAA showed higher values for the U15 throughout the season. In the U15, significant difference (p = .023) was found for sIgA concentration with higher concentration values in January compared to December (-42.7%; p = .008) and the sT showed seasonal variation (p < .001) with the highest value in January significantly different from October (-40.2%; p = .035), November (-38.5%; p = 0.022) and December (-51.6%; p = .008). The U19 presented an increase in sC in March compared to February (-66.1%, p = .018), sT/C were higher in February compared to March (-58.1%; p = .022) and sAA increased in March compared to September (-20.5%; p = .037). Negative correlations, controlled for age group, were found between URS occurrence and srIgA (r = -0.170, p = .001), sAA (r = -0.179, p = .001) and sT (r = -0.107, p = .047). Monitoring salivary biomarkers provides information on mucosal immunity with impact in URS occurrence. Coaches could manipulate training loads to attenuate the physical stressors imposed on athletes, especially at demanding and stressful periods.


Assuntos
Atletas , Imunidade nas Mucosas , Doenças Respiratórias/imunologia , Saliva/imunologia , Futebol , Adolescente , Biomarcadores/metabolismo , Humanos , Hidrocortisona/metabolismo , Imunoglobulina A Secretora/metabolismo , Masculino , Estações do Ano , Testosterona/metabolismo , alfa-Amilases/metabolismo
4.
Food Chem ; 330: 127313, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32569932

RESUMO

Starch granule-surface proteins (SGSPs) and granule-channel proteins (SGCPs) are granule-associated proteins (SGAPs), which have been found to be distributed on the surface and channels of starch granules, respectively. To investigate the impacts of SGAPs on α-amylase hydrolysis of starch, SGCPs or SGAPs of waxy, low and high amylose rice starches were removed. Removal of SGAPs or SGCPs greatly increased hydrolysis rate of rice starches. Meanwhile, these granules incurred a greater number and size of pores on their surfaces during hydrolysis. Compared to low and high amylose starches, waxy starch before and after removing SGAPs exhibited a higher hydrolysis rate. Rice starch hydrolysis began with enlargement of cavity and channels both horizontally and vertically. XRD analysis revealed that removal of SGAPs decreased relative crystallinity (RC) of starch and advanced changes in RC during hydrolysis process. This study provides new information about the role of SGAPs in the mechanisms of α-amylase hydrolysis.


Assuntos
Oryza/química , Proteínas de Plantas/química , Amido/química , alfa-Amilases/metabolismo , Amilose/metabolismo , Hidrólise , Oryza/metabolismo , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Amido/metabolismo , Amido/farmacocinética , Difração de Raios X , alfa-Amilases/química
5.
Food Chem ; 330: 127328, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32569940

RESUMO

Granular protein is an important structural feature in determining starch digestibility. High-amylose wheat starch (HAWS) with >80% amylose content contains more granular protein than wild-type starch. As analyzed by mass spectrometry-based proteomics, granular-bound starch synthase (GBSS) is the major granular protein in isolated starch materials. GBSS content increases with amylose content (Spearman's correlation, p < 0.05), whereas the abundance relative to other proteins is similar among starches. Multiple amylase inhibitors were also identified. From Michaelis-Menten analysis, HAWS has a similar Km (Michaelis constant) as wild type, suggesting initial enzymatic binding is similar. After the pre-digestion of proteins, wild type had a greater change in starch digestibility than HAWS, probably due to the latter having 'thicker' granular-protein layers and higher enzymatic resistance of substrate per se. Overall, the study suggests that the greater granular protein content in HAWS is a factor that contributes to slower amylolysis compared to wild type.


Assuntos
Amilose/metabolismo , Proteínas de Plantas/metabolismo , Sintase do Amido/metabolismo , Amido/química , Triticum/química , Amilose/análise , Amilose/química , Digestão , Hidrólise , Cinética , Proteínas de Plantas/análise , Amido/metabolismo , Sintase do Amido/análise , Espectrometria de Massas em Tandem , Triticum/metabolismo , alfa-Amilases/química , alfa-Amilases/metabolismo
6.
Food Chem ; 328: 126930, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32485581

RESUMO

The objective of this study was to quantify the phenolic compounds and to evaluate and compare the biological activities of the ethyl acetate (EtOAc), methanolic (MeOH) and aqueous extracts from the Micromeria nervosa aerial parts, based on their antioxidant activity and enzymatic inhibition. Total phenolic and flavonoid contents were calculated and individual compo3unds were detected using LC-ESI-MS/MS. The antioxidant activity was determined using six different assays while enzymatic activity was determined by α-amylase and tyrosinase enzyme inhibition. The main phenolic constituents detected in the extracts were rosmarinic acid. In the antioxidant assays the aqueous extract was shown to be more efficient than the others. The EtOAc and MeOH extracts presented higher inhibitory activity with respect to α-amylase and tyrosinase. Regardless of the solvent, the results suggest M. nervosa aerial extracts present a biological potential due to their antioxidant activity and enzymatic inhibition.


Assuntos
Antioxidantes/química , Inibidores Enzimáticos/análise , Lamiaceae/química , Fenóis/análise , Extratos Vegetais/química , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão , Cinamatos/análise , Depsídeos/análise , Flavonoides/análise , Lamiaceae/metabolismo , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/metabolismo , Componentes Aéreos da Planta/química , Componentes Aéreos da Planta/metabolismo , alfa-Amilases/antagonistas & inibidores , alfa-Amilases/metabolismo
7.
Food Chem ; 331: 127240, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32585546

RESUMO

The present study focused on the phytochemical profiling along with evaluation of in vitro antioxidant, α-glucosidase and α-amylase inhibitory activities of various crudes and fractions obtained from Lepisanthes fruticosa (Roxb) Leenh fruit. Ethanolic seed crude extract exhibited the strongest radical scavenging, ß-carotene bleaching activity, α-glucosidase inhibition and the highest total phenolic content (TPC). Column chromatography afforded various fractions with fraction M4 being the most potent due to the strongest radical scavenging, ß-carotene bleaching, α-glucosidase inhibition and greatest amount of TPC. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of ethanolic seed crude extract and fraction M4 showed the presence of various phytochemicals with antioxidant and antidiabetic properties, which include mostly flavonoids and tannins. The results may suggest that the ethanolic crude seed extract and its fraction could be an excellent source of bioactive phytochemicals with antioxidant and antidiabetic potential.


Assuntos
Antioxidantes/química , Inibidores Enzimáticos/análise , Fenóis/análise , Extratos Vegetais/química , Sapindaceae/química , Cromatografia Líquida de Alta Pressão , Inibidores Enzimáticos/química , Flavonoides/análise , Flavonoides/química , Frutas/química , Frutas/metabolismo , Fenóis/química , Sapindaceae/metabolismo , Espectrometria de Massas em Tandem , alfa-Amilases/antagonistas & inibidores , alfa-Amilases/metabolismo , alfa-Glucosidases/química , alfa-Glucosidases/metabolismo
8.
Nat Commun ; 11(1): 2644, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32457471

RESUMO

Cold-adapted enzymes from psychrophilic species show the general characteristics of being more heat labile, and having a different balance between enthalpic and entropic contributions to free energy barrier of the catalyzed reaction compared to mesophilic orthologs. Among cold-adapted enzymes, there are also examples that show an enigmatic inactivation at higher temperatures before unfolding of the protein occurs. Here, we analyze these phenomena by extensive computer simulations of the catalytic reactions of psychrophilic and mesophilic α-amylases. The calculations yield temperature dependent reaction rates in good agreement with experiment, and also elicit the anomalous rate optimum for the cold-adapted enzyme, which occurs about 15 °C below the melting point. This result allows us to examine the structural basis of thermal inactivation, which turns out to be caused by breaking of a specific enzyme-substrate interaction. This type of behaviour is also likely to be relevant for other enzymes displaying such anomalous temperature optima.


Assuntos
alfa-Amilases/química , alfa-Amilases/metabolismo , Adaptação Biológica , Animais , Biocatálise , Domínio Catalítico , Temperatura Baixa , Simulação por Computador , Estabilidade Enzimática , Cinética , Modelos Moleculares , Simulação de Dinâmica Molecular , alfa-Amilases Pancreáticas/química , alfa-Amilases Pancreáticas/metabolismo , Conformação Proteica , Pseudoalteromonas/enzimologia , Sus scrofa , Termodinâmica
9.
Can J Microbiol ; 66(9): 521-528, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32259457

RESUMO

Codon usage bias exists in almost every organism and is reported to regulate protein translation efficiency and folding. Besides translation, the preliminary role of codon usage bias on gene transcription has also been revealed in some eukaryotes such as Neurospora crassa. In this study, we took as an example the α-amylase-coding gene (amyA) and examined the role of codon usage bias in regulating gene expression in the typical prokaryote Escherichia coli. We confirmed the higher translation efficiency on codon-optimized amyA RNAs and found that the RNA level itself was also affected by codon optimization. The decreased RNA level was caused at least in part by altered mRNA stability at the post-transcriptional level. Codon optimization also altered the number of cytosine methylation sites. Examination on dcm knockouts suggested that cytosine methylation may be a minor mechanism adopted by codon bias to regulate gene RNA levels. More studies are required to verify the global effect of codon usage and to reveal its detailed mechanism on transcription.


Assuntos
Uso do Códon , Citosina/metabolismo , Metilação de DNA , Escherichia coli/genética , RNA Bacteriano/genética , RNA Mensageiro/genética , alfa-Amilases/genética , Códon , Neurospora crassa/genética , Estabilidade de RNA , alfa-Amilases/metabolismo
10.
Artigo em Inglês | MEDLINE | ID: mdl-32320287

RESUMO

The present study aimed to elucidate the mechanisms by which leucine impacts the secretion of pancreatic enzymes, especially amylase, by studying the proteomics profiles of pancreatic acinar (PA) cells from dairy cows. PA cells, the experimental model, were treated with four concentrations of leucine (0, 0.23, 0.45, and 0.90 mM). The abundance of different proteins in the four leucine treatment groups was detected. Label-free proteomic analysis enabled the identification of 1,906 proteins in all four treatment groups, and 1,350 of these proteins showed common expression across the groups. The primary effects of leucine supplementation were increased (P < 0.05) citrate synthase and ATPase activity, which enlarged the cytosolic ATP pool, and the upregulation of secretory protein 61 (Sec61) expression, which promoted protein secretion. In summary, these results suggest that leucine increases citrate synthase in the TCA cycle and ATPase activity and promotes the Sec signaling pathway to increase the exocrine function of PA cells.


Assuntos
Células Acinares/efeitos dos fármacos , Ciclo do Ácido Cítrico/efeitos dos fármacos , Leucina/farmacologia , Pâncreas Exócrino/efeitos dos fármacos , Via Secretória/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , alfa-Amilases/metabolismo , Células Acinares/enzimologia , Trifosfato de Adenosina/metabolismo , Animais , Animais Recém-Nascidos , Bovinos , Células Cultivadas , Citrato (si)-Sintase/metabolismo , Indústria de Laticínios , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Pâncreas Exócrino/enzimologia , Proteômica , Canais de Translocação SEC/metabolismo
11.
Arch Biochem Biophys ; 687: 108369, 2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32335047

RESUMO

A neutral tea polysaccharide (TPSN) was isolated from green tea. Gas chromatography analysis showed that TPSN was composed of d-glucose, l-arabinose and d-galactose residues at a molar ratio of 90.0: 9.1: 0.9. The weight-averaged molecular weight of TPSN was determined as about 2.0 × 105 g mol-1 using static light scattering analysis. The result of nuclear magnetic resonance (NMR) spectroscopy indicated that TPSN and water-soluble starch had similar structures. TPSN exhibited inhibitory activity towards α-amylase through the noncompetitive inhibition mechanism, but the tertiary structure of α-amylase related to enzymatic activity, analyzed using circular dichroism spectroscopy, was not affected by TPSN. Meanwhile, TPSN exhibited hydrolysis properties catalyzed by α-amylase. Molecular docking analysis revealed that the various behaviors of TPSN to α-amylase could be attributed to that the different chain segments of TPSN combined with different amino acid residues of α-amylase.


Assuntos
Inibidores Enzimáticos/química , Polissacarídeos/química , Chá/química , alfa-Amilases/antagonistas & inibidores , Animais , Camellia sinensis/química , Ensaios Enzimáticos , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/metabolismo , Hidrólise , Cinética , Simulação de Acoplamento Molecular , Peso Molecular , Polissacarídeos/isolamento & purificação , Polissacarídeos/metabolismo , Ligação Proteica , Suínos , alfa-Amilases/metabolismo
12.
Food Chem ; 318: 126477, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32126465

RESUMO

Water-extractable arabinoxylan (WEAX) could effectively improve the cereal food quality, while its regulatory effect on wheat starch properties has yet to be well-understood. This study selected the WEAX with different molecular weight (Mw) but same branched degree, and comparatively investigated their effects on the gelatinization and retrogradation behavior of wheat starch. The decreased degree of swelling power, solubility and peak viscosity suggested that low Mw WEAX (L-WEAX) could hinder starch gelatinization more evidently compared with high Mw WEAX (H-WEAX), due to the pronounced inhibition effect on amylose leaching and amylose-lipid complex formation. L-WEAX suppressed the recrystallization of amylose and thus the short-term retrogradation. However, H-WEAX mainly retarded the recrystallization of amylopectin, exerting a more significant inhibition effect on the long-term retrogradation. This study could provide a theoretical basis for enhancing the quality and extending the shelf life of starchy foods by selecting the optimum structure of WEAX.


Assuntos
Amido/química , Triticum/química , Xilanos/isolamento & purificação , Amilopectina/química , Amilose/química , Varredura Diferencial de Calorimetria , Cristalização , Gelatina/química , Microscopia Confocal , Peso Molecular , Viscosidade , Água/química , Difração de Raios X , Xilanos/química , alfa-Amilases/química , alfa-Amilases/metabolismo
13.
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
14.
Food Chem ; 320: 126491, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32208185

RESUMO

Glycosidic linkage structure, physical-chemical properties and in vitro digestibility of pyrodextrins prepared using different reaction conditions were characterized. Intensification of reaction condition promoted starch hydrolysis and transglucosidation until the solubility of pyrodextrin reached 100%. New branch points were formed including α-1,2, ß-1,2, ß-1,4, ß-1,6 and α-1,6 linkages. Majority of the branch points was α-1,6 and ß-1,6 linkages which in together accounted for more than 70% of the total branches. The degree of branching increased at intensified reaction conditions and plateaued at approximately 24%. Exhaustively hydrolyzing pyrodextrin by α-amylase and amyloglucosidase significantly decreased the degree of α-1,4 but not α-1,6 linkages. The retained α-1,4 and α-1,6 linkages were probably protected from enzyme hydrolysis by the non-starch linkages due to steric hindrance. The resistant starch content was positively correlated with the degree of branching of pyrodextrin. The decreased in vitro digestibility of pyrodextrin was attributed to the formation of new glycosidic linkages.


Assuntos
Dextrinas/química , Dextrinas/metabolismo , Glucana 1,4-alfa-Glucosidase/metabolismo , Hidrólise , Amido/química , Zea mays/química , alfa-Amilases/metabolismo
15.
Apunts, Med. esport (Internet) ; 55(205): 29-37, ene.-mar. 2020. tab, graf
Artigo em Inglês | IBECS | ID: ibc-192335

RESUMO

INTRODUCTION: The aim of these studies was to evaluate the effects of regular volleyball training on salivary SIgA and alpha-amylase in female children and adolescents. MATERIAL AND METHOD: In the cross-sectional study, 115 female children (12.6 ± 2.2 years) participating in a Volleyball training program were classified as beginners, intermediate, and competitive level. The children were evaluated regarding caries index, body mass index (BMI), cardiorespiratory fitness, and countermovement jump. In the longitudinal study: 54 girls (intermediate and competitive groups) trained for 8 weeks and were re-evaluated at weeks 4 and 8. RESULTS: The SIgA secretion rate and alpha-amylase activity did not present correlations with training category, age, caries index, or training status. A weak positive correlation was detected between IgA secretion rate and BMI (r = 0.20, p < 0.05). After 8 weeks of training, VO2max (p < 0.005) and jump height (p < 0.005) improved in the competitive girls. No differences were observed in salivary secretion rate, SIgA concentration and secretion rate, or alpha-amylase activity at weeks 4 and 8. CONCLUSIÓN: We concluded that despite improving physical fitness, 8-weeks of recreational volleyball training are not able to improve salivary SIgA secretion or alter alpha-amylase activity in female children and adolescents


No disponible


Assuntos
Humanos , Feminino , Criança , Adolescente , Voleibol/fisiologia , Saliva/imunologia , Imunoglobulina A Secretora/metabolismo , Saliva/metabolismo , alfa-Amilases/metabolismo , Estudos Transversais , Estudos Longitudinais , Índice de Massa Corporal , Estudos de Coortes , Teste de Esforço
16.
J Biotechnol ; 312: 1-10, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32119878

RESUMO

Promoter plays the critical role in regulating gene transcription, and dual-promoter has received the widespread attentions due to its high efficiency and continuity, here, we want to construct an efficient dual-promoter for protein production and metabolic pathway enhancement. Firstly, our results indicated that P43 promoter efficiently transcribed at logarithmic period, while the σB-type promoters (PylB, PgsiB, PykzA) were active at stationary phase. Then, several dual promoters were constructed by coupling these σB-type promoters with P43, and the attained dual-promoter PykzA-P43 showed the best performance, which led to 1.72-, 3.46- and 1.85-fold increases of green fluorescence intensity, red fluorescence intensity and α-amylase activity, compared with those of the recognized strong promoter P43, respectively. Furthermore, α-amylase activity was further increased to 389.65 U/mL by 32.20 % via optimizing sigma factor binding sites (-10 and -35 boxes) of PykzA-P43, attaining the optimized dual promoter Pdual3. Finally, Pdual3 was applied in metabolic pathway enhancement, and the yields of Poly γ-glutamic acid, acetoin and 2, 3-butanediol were respectively improved by 82.01 %, 17.09 % and 99.39 %. Our results indicated that dual-promoter significantly enhanced gene expression, and this study provided an energetic dual-promoter Pdual3 for efficient protein production and metabolic pathway enhancement in Bacillus licheniformis.


Assuntos
Bacillus licheniformis/genética , Bacillus licheniformis/metabolismo , Redes e Vias Metabólicas/genética , Regiões Promotoras Genéticas/genética , Acetoína/metabolismo , Bacillus licheniformis/enzimologia , Butileno Glicóis/metabolismo , Regulação Bacteriana da Expressão Gênica , Ácido Poliglutâmico/análogos & derivados , alfa-Amilases/genética , alfa-Amilases/metabolismo
17.
Food Chem ; 317: 126346, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070843

RESUMO

The inhibitory mechanisms of ferulic acid against α-amylase and α-glucosidase were investigated by enzyme kinetic analysis, circular dichroism (CD), Fourier-transform infrared (FT-IR) spectroscopy, fluorescence quenching and molecular docking. Results indicated that ferulic acid strongly inhibited α-amylase (IC50: 0.622 mg ml-1) and α-glucosidase (IC50: 0.866 mg ml-1) by mixed and non-competitive mechanisms, respectively. CD spectra and fluorescence intensity measurements confirmed that the secondary structure of α-amylase and α-glucosidase were changed and the microenvironments of certain amino acid residues were modulated by the binding of ferulic acid. FT-IR spectra indicated that the interaction between ferulic acid and α-amylase/α-glucosidase mainly involved in non-covalent bonds. Molecular docking further demonstrated that the interaction forces between ferulic acid and α-amylase/α-glucosidase were hydrogen bonds, with the binding energy of -5.30 to -5.10 and -5.70 kcal mol-1, respectively. This study might provide a theoretical basis for the designing of novel functional foods with ferulic acid.


Assuntos
Ácidos Cumáricos/metabolismo , Inibidores de Glicosídeo Hidrolases/metabolismo , alfa-Amilases/metabolismo , alfa-Glucosidases/metabolismo , Sítios de Ligação , Ácidos Cumáricos/química , Inibidores de Glicosídeo Hidrolases/química , Ligação de Hidrogênio , Cinética , Simulação de Acoplamento Molecular , Estrutura Secundária de Proteína , Termodinâmica , alfa-Amilases/química , alfa-Glucosidases/química
18.
Animal ; 14(S1): s17-s28, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32024574

RESUMO

Pregastric fermentation along with production practices that are dependent on high-energy diets means ruminants rely heavily on starch and protein assimilation for a substantial portion of their nutrient needs. While the majority of dietary starch may be fermented in the rumen, significant portions can flow to the small intestine. The initial phase of small intestinal digestion requires pancreatic α-amylase. Numerous nutritional factors have been shown to influence pancreatic α-amylase secretion with starch producing negative effects and casein, certain amino acids and dietary energy having positive effects. To date, manipulation of α-amylase secretion has not resulted in substantial changes in digestibility. The second phase of digestion involves the actions of the brush border enzymes sucrase-isomaltase and maltase-glucoamylase. Genetically, ruminants appear to possess these enzymes; however, the absence of measurable sucrase activity and limited adaptation with changes in diet suggests a reduced capacity for this phase of digestion. The final phase of carbohydrate assimilation is glucose transport. Ruminants possess Na+-dependent glucose transport that has been shown to be inducible. Because of the nature of pregastric fermentation, ruminants see a near constant flow of microbial protein to the small intestine. This results in a nutrient supply, which places a high priority on protein digestion and utilization. Comparatively, little research has been conducted describing protein assimilation. Enzymes and processes appear consistent with non-ruminants and are likely not limiting for efficient digestion of most feedstuffs. The mechanisms regulating the nutritional modulation of digestive function in the small intestine are complex and coordinated via the substrate, neural and hormonal effects in the small intestine, pancreas, peripheral tissues and the pituitary-hypothalamic axis. More research is needed in ruminants to help unravel the complexities by which small intestinal digestion is regulated with the aim of developing approaches to enhance and improve the efficiency of small intestinal digestion.


Assuntos
Aminoácidos/metabolismo , Carboidratos da Dieta/metabolismo , Ingestão de Energia , Proteínas/metabolismo , Ruminantes/metabolismo , Amido/metabolismo , Animais , Caseínas/metabolismo , Dieta/veterinária , Digestão , Fermentação , Intestino Delgado/metabolismo , Pâncreas/enzimologia , Rúmen/metabolismo , alfa-Amilases/metabolismo
19.
J Biosci Bioeng ; 129(6): 679-686, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32089433

RESUMO

Nanoflowers are recently developed flower-shaped nanoparticles consisting of several layers of petals to improve surface reaction and stability. Among them organic-inorganic hybrid nanoflowers have been spotlighted, since they can overcome enzyme-related limitations, including low stability, high production cost, substrate/product inhibition and difficult recovery. In this study, triple enzyme-inorganic hybrid nanoflowers (TrpE@ihNFs) were synthesized using a mixture of three enzymes (α-amylase, lipase and protease) and Cu2+ ions. TrpE@ihNFs were characterized by their morphology and chemical point of view by using different techniques including SEM, FTIR, EDX, and XRD. Afterwards we compared the enzyme activity and stability of TrpE@ihNFs with the free enzymes, including lipase, amylase and protease at the different pH and temperatures spectrophotometrically. Our data reveal that enzyme activities and stability of TrpE@ihNFs were significantly higher compared to the each free enzyme. In conclusion, we showed TrpE@ihNFs which can be used for the treatment of wastewater, biosensors, biocatalysts, and bio-related devices in the future.


Assuntos
Endopeptidases/metabolismo , Lipase/metabolismo , Nanopartículas , alfa-Amilases/metabolismo , Concentração de Íons de Hidrogênio , Lipase/química , Pâncreas , Temperatura
20.
Curr Pharm Biotechnol ; 21(9): 872-881, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32000641

RESUMO

OBJECTIVE: Amylases enzymes hydrolyze starch molecules to produce diverse products including dextrins, and progressively smaller polymers. These include glucose units linked through α-1- 1, α-1-4, α-1-6, glycosidic bonds. METHODS: This enzyme carrying an (α /ß) 8 or TIM barrel structure is also produced containing the catalytic site residues. These groups of enzymes possess four conserved regions in their primary sequence. In the Carbohydrate-Degrading Enzyme (CAZy) database, α-amylases are classified into different Glycoside Hydrolase Families (GHF) based on their amino acid sequence. The present objective was to study one such enzyme based on its molecular characterization after purification in our laboratory. Its main property of solid-natural starch degradation was extensively investigated for its pharmaceutical/ industrial applications. RESULTS: Amylase producing bacteria Bacillus cereus sm-sr14 (Accession no. KM251578.1) was purified to homogeneity on a Seralose 6B-150 gel-matrix and gave a single peak during HPLC. MALDITOF mass-spectrometry with bioinformatics studies revealed its significant similarity to α/ß hydrolase family. The enzyme showed an efficient application; favourable Km, Vmax and Kcat during the catalysis of different natural solid starch materials. Analysis for hydrolytic product showed that this enzyme can be classified as the exo-amylase asit produced a significant amount of glucose. CONCLUSION: Besides the purified enzyme, the present organism Bacillus cereus sm-sr14 could degrade natural solid starch materials like potato and rice up to the application level in the pharmaceutical/ industrial field for alcohol production.


Assuntos
Bacillus cereus/enzimologia , Etanol/metabolismo , Amido/metabolismo , alfa-Amilases/isolamento & purificação , alfa-Amilases/metabolismo , Sequência de Aminoácidos , Biotecnologia , Estabilidade Enzimática , Preparações Farmacêuticas , Especificidade por Substrato
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA