Showing papers on "Amylase published in 2008"
TL;DR: The findings show that certain naturally occurring flavonoids act as inhibitors of human alpha-amylase, which makes them promising candidates for controlling the digestion of starch and postprandial glycemia.
Abstract: In this study we investigated the structural requirements for inhibition of human salivary alpha-amylase by flavonoids. Four flavonols and three flavones, out of the 19 flavonoids tested, exhibited IC50 values less than 100 microM against human salivary alpha-amylase activity. Structure-activity relationships of these inhibitors by computational ligand docking showed that the inhibitory activity of flavonols and flavones depends on (i) hydrogen bonds between the hydroxyl groups of the polyphenol ligands and the catalytic residues of the binding site and (ii) formation of a conjugated pi-system that stabilizes the interaction with the active site. Our findings show that certain naturally occurring flavonoids act as inhibitors of human alpha-amylase, which makes them promising candidates for controlling the digestion of starch and postprandial glycemia.
388 citations
TL;DR: Data suggest that BAM4 facilitates or regulates starch breakdown and operates independently of BAM1 and BAM3, consistent with the proposal that β-amylase is a major enzyme of starch breakdown in leaves, but they reveal unexpected complexity in terms of the specialization of protein function.
Abstract: This work investigated the roles of β-amylases in the breakdown of leaf starch. Of the nine β-amylase (BAM)–like proteins encoded in the Arabidopsis thaliana genome, at least four (BAM1, -2, -3, and -4) are chloroplastic. When expressed as recombinant proteins in Escherichia coli, BAM1, BAM2, and BAM3 had measurable β-amylase activity but BAM4 did not. BAM4 has multiple amino acid substitutions relative to characterized β-amylases, including one of the two catalytic residues. Modeling predicts major differences between the glucan binding site of BAM4 and those of active β-amylases. Thus, BAM4 probably lost its catalytic capacity during evolution. Total β-amylase activity was reduced in leaves of bam1 and bam3 mutants but not in bam2 and bam4 mutants. The bam3 mutant had elevated starch levels and lower nighttime maltose levels than the wild type, whereas bam1 did not. However, the bam1 bam3 double mutant had a more severe phenotype than bam3, suggesting functional overlap between the two proteins. Surprisingly, bam4 mutants had elevated starch levels. Introduction of the bam4 mutation into the bam3 and bam1 bam3 backgrounds further elevated the starch levels in both cases. These data suggest that BAM4 facilitates or regulates starch breakdown and operates independently of BAM1 and BAM3. Together, our findings are consistent with the proposal that β-amylase is a major enzyme of starch breakdown in leaves, but they reveal unexpected complexity in terms of the specialization of protein function.
295 citations
TL;DR: In this article, the anti-diabetic-relevant potential of wines and teas were confirmed in four types of red and white wines as well as four commonly available teas using in vitro enzyme assays for alpha-glucosidase and alpha-amylase inhibitory activities.
Abstract: Natural α-amylase and α-glucosidase inhibitors from food-grade plants offer an attractive strategy to manage postprandial hyperglycemia for type 2 diabetes management via control of starch breakdown and intestinal glucose absorption. In this study, four random sources of red and white wines as well as four types of teas were investigated for α-amylase and α-glucosidase inhibitory potential. Water extracts of black tea had the highest α-glucosidase inhibitory activity, followed by white tea and oolong tea. All the randomly selected red wines had significant α-glucosidase inhibitory activity compared to white wine. The α-glucosidase inhibitory activity of the tea and wines correlated to the phenolic content, antioxidant activity and phenolic profile of the extracts. Further, these extracts had less or no α-amylase inhibitory activity, indicating potential to overcome the side effects of undigested starch. This research has relevance for managing hyperglycemia and related oxidation-linked dysfunction and concurrently reducing problems of undigested starch.
PRACTICAL APPLICATIONS
In this study anti-diabetic-relevant potential of wines and teas were confirmed in four types of red and white wines as well as four types of commonly available teas using in vitro enzyme assays for alpha-glucosidase and alpha-amylase inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for type 2 diabetes through the control of glucose absorption. Further this phenolic antioxidant-enriched dietary strategy using specific beverage combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress.
227 citations
TL;DR: The changes found suggest that enzyme resistant starch does not refer to a specific structure present in predigested starches, but may in fact be formed during the digestion process through the rearrangement of amylose chains into enzyme-resistant structures of higher crystallinity.
206 citations
TL;DR: The enzyme preparation had a strong digesting ability towards various raw starches and efficiently hydrolyzed raw corn starch at a concentration of 20% and pH 5.0, which were normally used in the starch industries, in a period of 12h.
189 citations
TL;DR: It is concluded that the energy and amino acid values of maize-based diets for broilers can be enhanced by supplementation with an enzyme cocktail of xylanase, amylase and protease, offering potential economic benefits to producers.
Abstract: 1. A total of 192 male broilers (Cobb 500) were used in a growth and digestibility assay, involving a 2 x 2 factorial arrangement of treatments, to assess the effects of an enzyme cocktail of xylanase, amylase and protease in maize-based diets. 2. The following two diets were formulated: a positive control diet containing adequate nutrient concentrations for broiler starters as per breeder recommendations and a negative control diet to contain approximately 0.63 MJ/kg apparent metabolisable energy (AME) and 3% amino acids less than the positive control. 3. A further two dietary treatments were developed by supplementing each control diet with an enzyme product containing xylanase, amylase and protease. 4. Birds fed on the negative control diet had poorer weight gain and feed efficiency than those given the positive control diet. There was no effect of diet or enzyme on feed intake. The digestibility of nitrogen, calcium, phosphorus and most amino acids were unaffected by dietary nutrient density. 5. Supplementation of both the positive and negative control diets with the enzyme improved weight gain and feed efficiency compared with the unsupplemented diets. In the case of the negative control, supplemental enzyme improved performance to that of the unsupplemented positive control diet. There was no interaction between diet and enzyme for either weight gain or FCR, suggesting similar beneficial responses regardless of the nutrient density of the diet. 6. In both diets, enzyme supplementation improved AME by an average of 3% (0.35 MJ/kg DM) and nitrogen retention by an average of 11.7% (26 g/kg DM intake vs 29 g/kg DM intake). There was no interaction between diet and enzyme for AME or nitrogen retention. 7. Ileal digestibilities of calcium and phosphorus were not influenced by supplemental enzyme, whereas the digestibility of nitrogen and most amino acids was improved by enzyme addition compared with the unsupplemented control diets. There was no interaction between diet and enzyme for the ileal digestibility of nitrogen and amino acids. 8. These data demonstrate that it is possible to improve the nutritional value of a maize/soy-based diet for broiler starters through the use of exogenous enzymes. The nutrient density of the diet does not appear markedly to influence the response to enzyme, offering flexibility in the use of enzymes for maize-based diets. 9. It is concluded that the energy and amino acid values of maize-based diets for broilers can be enhanced by supplementation with an enzyme cocktail of xylanase, amylase and protease, offering potential economic benefits to producers.
187 citations
TL;DR: A family of three glycosylated acyl flavonols, montbretins A–C, was thereby identified and characterized as competitive amylase inhibitors, with Ki values ranging from 8.1–6100 nM, which suggest a binding mode for these inhibitors.
Abstract: Specific inhibitors of human pancreatic alpha-amylase (HPA) have potential as oral agents for the control of blood glucose levels in the treatment of diabetes and obesity. In a search for novel inhibitors, a library of 30 000 crude biological extracts of terrestrial and marine origin has been screened. A number of inhibitory extracts were identified, of which the most potent was subjected to bioassay-guided purification. A family of three glycosylated acyl flavonols, montbretins A-C, was thereby identified and characterized as competitive amylase inhibitors, with K(i) values ranging from 8.1-6100 nM. Competitive inhibition by myricetin, which corresponds to the flavone core, and noncompetitive inhibition by a second fragment, ethyl caffeiate, suggest a binding mode for these inhibitors.
184 citations
TL;DR: GC, FTIR, and 1H NMR analysis of the polymer indicated that the strain was a potent polyhydroxybutyrate (PHB) producer and the bacterium accumulated about 48% PHA in CDW in a starch containing medium.
Abstract: A bacterial strain that produces amylase and polyhydroxyalkanoate (PHA) was isolated, identified, and classified under the Bacillus cereus group based on 16S rRNA gene sequences and specific reaction in poly-myxin egg yolk Mannitol bromothymol blue agar (PEMBA) medium and in combination with microbiological and biochemical tests. The complete ORF of phaC gene was cloned by PCR technique and nucleotide sequences were determined. Results indicated that the phaC gene had 99% homology with phaC of B. cereus (AE016877.1), 98% with B. thuringiensis (AY331151.1), and 94% with several strains of B. anthracis and B. cereus group including Bacillus sp. INT005. However, only 90% sequence homology with phaC of B. megaterium (AF109909.2) was observed. The PHA production using different fermentable sugars was tested and it was found that the CFR06 was able to accumulate 36–60% of PHA in cell dry weight (CDW). Zymogram of amylase indicated that native strain produces an extracellular enzyme of ∼80 kDa. The potency of the organism to hydrolyze starch due to the intrinsic amylase activity was considered, and starch was used as the sole carbon source for growth and PHA production. GC, FTIR, and 1H NMR analysis of the polymer indicated that the strain was a potent polyhydroxybutyrate (PHB) producer. The bacterium accumulated about 48% PHA in CDW in a starch containing medium.
139 citations
TL;DR: The present review assesses the potential of the Phaseolus vulgaris α-amylase inhibitor isoform 1 (α-AI1) starch blockers as a widely used remedy against obesity and diabetes and the need for research into their potential anti-colorectal cancer effect is discussed.
Abstract: The present review assesses the potential of the Phaseolus vulgaris α-amylase inhibitor isoform 1 (α-AI1) starch blockers as a widely used remedy against obesity and diabetes. Consumption of the α-amylase inhibitor causes marginal intraluminal α-amylase activity facilitated by the inhibitor's appropriate structural, physico-chemical and functional properties. As a result there is decreased postprandial plasma hyperglycaemia and insulin levels, increased resistance of starch to digestion and increased activity of colorectal bacteria. The efficacy and safety of the amylase inhibitor extracts, however, depend on the processing and extraction techniques used. The extracts are potential ingredients in foods for increased carbohydrate tolerance in diabetics, decreased energy intake for reducing obesity and for increased resistant starch. Research developments in the distribution and biosynthesis of the α-amylase inhibitor, relevant physico-chemical properties, the molecular starch-blocking mechanism, anti-obesity and anti-diabetes effects, safety of extracts and the need for research into their potential anti-colorectal cancer effect are discussed.
134 citations
TL;DR: In this article, a bacterial strain was isolated from soil sample receiving kitchen waste and growth pattern as well as optimum growth condition was determined, the optimum temperature for this strain was 37oC, whereas maximum growth was observed at 2% starch concentration.
Abstract: Starch degrading bacteria are most important for industries such as food, fermentation, textile and paper. Thus isolating and manipulating pure culture from various waste materials has manifold importance for various biotechnology industries. In the present investigation a bacterial strain was isolated from soil sample receiving kitchen waste and growth pattern as well as optimum growth condition was determined. Characteristic feature of the strain indicates that it belongs to the genus Bacillus. The optimum temperature for this strain was 37oC, whereas maximum growth was observed at 2% starch concentration. The pH range was found to be 6.8 - 7.2 for optimum growth. Amylase activity was maximum in the temperature range of 50 - 70oC, whereas this temperature range was deleterious for this bacterial strain. Also maximum enzyme activity was observed at 2% of starch concentration.
131 citations
TL;DR: Differing and regulating the composition of wheat bran used as a fermentation supplement may allow for improved induction of cellulase and xylanase production.
Abstract: The effects of the starch, protein, and soluble oligosaccharides contents in wheat bran on the extracellular biomass-hydrolyzing enzymes activities released by Penicillium decumbens mycelia grown in batch fermentations have been examined. The results showed increased starch content correlated directly with an increase in released amylase activity but inversely with the levels of secreted cellulase and xylanase. High amounts of protein in wheat bran also reduced the activities of cellulase, xylanase and protease in the culture medium. The effects of the soluble and insoluble components of wheat bran and cello-oligosaccharides supplements on production of extracellular cellulase and xylanase were compared. The soluble cello-oligosaccharides compositions in wheat bran were proved to be one of the most significant factors for cellulase production. According to the results of this research, determining and regulating the composition of wheat bran used as a fermentation supplement may allow for improved induction of cellulase and xylanase production.
TL;DR: The result showed that the A3-15 amylase enzyme was both, highly thermostable-alkaline, thermophile and chelator resistant and may be suitable in liquefaction of starch in high temperature, in detergent and textile industries and in other industrial applications.
TL;DR: Glucose, maltose, and maltooligosaccharides were the main end products of starch hydrolysis indicating that it is an alpha-amylase.
Abstract: A moderately halophilic alkalitolerant Bacillus sp. Strain TSCVKK, with an ability to produce extracellular halophilic, alkalitolerant, surfactant, and detergent-stable alpha-amylase was isolated from soil samples obtained from a salt-manufacturing industry in Chennai. The culture conditions for higher amylase production were optimized with respect to NaCl, substrate, pH, and temperature. Maximum amylase production of 592 mU/ml was achieved in the medium at 48 h with 10% NaCl, 1% dextrin, 0.4% yeast extract, 0.2% tryptone, and 0.2% CaCl2 at pH 8.0 at 30 °C. The enzyme activity in the culture supernatant was highest with 10% NaCl at pH 7.5 and 55 °C. The amylase that was partially purified by acetone precipitation was highly stable in various surfactants and detergents. Glucose, maltose, and maltooligosaccharides were the main end products of starch hydrolysis indicating that it is an alpha-amylase.
TL;DR: The mechanism and molecular structure of the slowly digestible waxy maize starch prepared by octenyl succinic anhydride (OSA) esterification and heat-moisture treatment were investigated and solubility analysis indicates that the water-insolubility of HOSA-starch is caused by OSA-mediated cross-linking of amylopectin and the hydrophobic interaction between OSO-modified starch molecules.
TL;DR: The results indicated that AFB1 of feed could decrease growth performance and apparent digestibility of nutrients, change digestive enzyme activities of duodenum contents in duck.
TL;DR: It is indicated that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.
Abstract: The effect of dietary phytate and phytase on carbohydrase activity and hexose transport was investigated in broiler chickens. Diets containing phytate P (2.2 or 4.4 g/kg) with different phytase dose rates (0, 500, or 1,000 phytase units/kg) were fed to 504 female Cobb chicks for 3 wk. Diets containing high phytate concentrations depressed (P < 0.05) BW and G:F, whereas phytase supplementation improved (P < 0.05) the performance of birds. In the duodenum, phytate decreased (P < 0.05) the activities of disaccharidases, Na + K + -ATPase, and glucose concentrations by 5 to 11%, but phytase enhanced (P < 0.05) the concentrations of amylase, sucrase, maltase, Na + K + -AT-Pase, and glucose by 5 to 30%. In the jejunum, phytate decreased (P < 0.05) the concentrations of amylase, sucrase, Na + K + -ATPase, and glucose by 10 to 22%, and phytase alleviated the negative effect of phytate on the above variables. Ingestion of diets containing phytate also decreased (P < 0.05) serum amylase activity and glucose concentration, and phytase enhanced (P < 0.05) serum concentrations of amylase, sucrase, maltase, Na + K + -ATPase, and glucose. There were also interactions (P < 0.05) between phytate and phytase on the concentrations of serum amylase, duodenal amylase, sucrase, and jejunal glucose. Enzymatic analysis at a molecular level showed that neither phytate nor phytase influenced the mRNA expression of sucrase-isomaltase in the small intestine. Also, the investigation into the sodium glucose cotransporter gene may challenge the mechanism by which phytate interferes with glucose utilization, as partly indicated by bird performance, and transmembrane transport because diets containing increased phytate upregulated (P < 0.05) the mRNA expression of the sodium glucose cotransporter gene in duodenum and did not influence it in the jejunum. These results indicate that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.
TL;DR: The effect of millet polyphenols on starch hydrolysis catalyzed by amylases developed during malting was investigated in this article, where the enzyme kinetic studies using Michaelis-Menten and Lineweaver-Burk equations showed the Km remained constant (0.625%) but the maximum velocity (Vmax) decreased in the presence of a crude extract of a milletpolyphenols, indicating mixed noncompetitive inhibition.
TL;DR: In this paper, a new amylase type TTI based on the reaction between amylases and starch was developed, which can be applied to show the time-temperature history of foodstuffs, and to indicate the food quality.
TL;DR: HBAPC and HBA showed higher water solubility and stability against retrogradation than amylopectin clusters or branched amylose, and are less susceptible to hydrolysis by glucoamylase and alpha-amylases.
Abstract: We enzymatically modified rice starch to produce highly branched amylopectin and amylose and analyzed the resulting structural changes. To prepare the highly branched amylopectin cluster (HBAPC), we first treated waxy rice starch with Thermus scotoductus α-glucanotransferase (TSαGT), followed by treatment with Bacillus stearothermophilus maltogenic amylase (BSMA). Highly branched amylose (HBA) was prepared by incubating amylose with Bacillus subtilis 168 branching enzyme (BBE) and subsequently treating it with BSMA. The molecular weight of TSαGT-treated waxy rice starch was reduced from 8.9 × 10 8 to 1.2 × 10 5 Da, indicating that the α-1,4 glucosidic linkage of the segment between amylopectin clusters was hydrolyzed. Analysis of the amylopectin cluster side chains revealed that a rearrangement in the side-chain length distribution occurred. Furthermore, HBAPC and HBA were found to contain significant numbers of branched maltooligosaccharide side chains. In short, amylopectin molecules of waxy rice starch...
TL;DR: The results suggest that the organic components of A. nodosum extract induce amylase activity independent of GA3 and might act in concert with GA-dependent amyl enzyme production leading to enhanced germination and seedling vigor in barley.
Abstract: Extracts of the brown seaweed Ascophyllum nodosum have been used as a biostimulant to promote growth and productivity in a number of agricultural production systems. Although the extracts have been shown to improve seedling emergence and vigor in a variety of plants, including barley, the mechanism(s) of this growth-promoting effect is(are) largely unknown. In our study, A. nodosum extract induced amylase activity in barley seed-halves; a significant difference in amylase activity was observed in seeds without an embryo. The addition of activated charcoal to the treatment media negated the bioactivity of the extracts suggesting the organic nature of bioactive compounds in A. nodosum extracts. The extracts induced amylase activity in a gibberellic acid (GA)-deficient barley mutant (grd2). LC-MS-MS analysis failed to detect the presence of GA3 in the extracts. ABA supplementation of the medium caused a significant reduction of amylase activity in GA-treated seeds compared with those treated with the A. nodosum extract. Taken together, our results suggest that the organic components of A. nodosum extract induce amylase activity independent of GA3 and might act in concert with GA-dependent amylase production leading to enhanced germination and seedling vigor in barley. Being derived from a renewable resource, the bioactive compounds from A. nodosum could be used to improve crop productivity in sustainable agricultural systems.
TL;DR: Results are consistent with previous observations showing that phytates and alpha-galactooligosaccharides decreased during the natural lactic acid fermentation of pearl millet slurries, and that partial starch hydrolysis can be performed by endogenous microflora provided a pre-gelatinisation step is included in the process.
TL;DR: The combination of starch and sucrose has profound effects not only on the composition and structure of the polysaccharide matrix but also on gene expression of S. mutans within bio Films, which may enhance the cariogenic potential of dental biofilms.
Abstract: Introduction: The combination of starch and sucrose has been shown to be potentially more cariogenic than either alone. The aim of this study was to examine the influence of starch and sucrose, alone or in combinations, on formation, polysaccharide composition, gene expression, and acidogenicity of Streptococcus mutans biofilms.
Methods: S. mutans UA159 biofilms were formed on saliva-coated hydroxyapatite (sHA) discs in batch culture for 5 days in the presence of 1% (weight/volume) starch, 1% sucrose, 1% starch plus 1% sucrose, 1% starch plus 0.5% fructose plus 0.5% glucose, or 1% sucrose plus 1% glucose.
Results: Amylase activity from sHA disks was detected up to 48 h, thereby increasing the availability of reducing sugars and acidogenicity in the early stages of biofilm development. S. mutans grown in the presence of sucrose alone or in combinations formed well-defined and tightly adherent biofilms comprised of mostly water-insoluble polysaccharides (INS); in contrast, the presence of starch or starch + glucose + fructose resulted in little biofilm formation with minimal amounts of INS. However, the combination of starch + sucrose produced biofilms with more biomass and acidogenicity, and a higher content of INS than those grown in sucrose or sucrose + glucose (P < 0.05). The INS extracted from biofilms formed in the presence of starch + sucrose displayed a higher percentage of 3-linked branching (3,4-, 3,6-, and 3,4,6-linked glucose) compared to those from biofilms grown in sucrose or sucrose + glucose. Furthermore, biofilms grown in starch + sucrose expressed significantly higher levels of gtfB messenger RNA than sucrose-grown or sucrose + glucose-grown biofilms (P < 0.05).
Conclusion: The combination of starch and sucrose has profound effects not only on the composition and structure of the polysaccharide matrix but also on gene expression of S. mutans within biofilms, which may enhance the cariogenic potential of dental biofilms.
TL;DR: This is the first report on the isolation and characterization of cold-adapted amylase from Nocardiopsis sp.
Abstract: An actinomycete strain 7326 producing cold-adapted α-amylase was isolated from the deep sea sediment of Prydz Bay, Antarctic. It was identified as Nocardiopsis based on morphology, 16S rRNA gene sequence analysis, and physiological and biochemical characteristics. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram activity staining of purified amylase showed a single band equal to a molecular mass of about 55 kDa. The optimal activity temperature of Nocardiopsis sp. 7326 amylase was 35°C, and the activity decreased dramatically at temperatures above 45°C. The enzyme was stable between pH 5 and 10, and exhibited a maximal activity at pH 8.0. Ca2+, Mn2+, Mg2+, Cu2+, and Co2+ stimulated the activity of the enzyme significantly, and Rb2+, Hg2+, and EDTA inhibited the activity. The hydrolysates of soluble starch by the enzyme were mainly glucose, maltose, and maltotriose. This is the first report on the isolation and characterization of cold-adapted amylase from Nocardiopsis sp.
TL;DR: Recombinant enzyme technology, protein engineering, and enzyme immobilization are powerful tools available to enhance the activity of enzymes, lower the cost of enzyme through large scale production in a heterologous host, increase their thermostability, improve pH stability, enhance their productivity and hence making it competitive with the chemical processes involved in starch hydrolysis and conversions.
Abstract: Many industrial products and functional foods can be obtained from cheap and renewable raw agricultural materials. For example, starch can be converted to bioethanol as biofuel to reduce the current demand for petroleum or fossil fuel energy. On the other hand, starch can also be converted to useful functional ingredients, such as high fructose and high maltose syrups, wine, glucose, and trehalose. The conversion process involves fermentation by microorganisms and use of biocatalysts such as hydrolases of the amylase superfamily. Amylases catalyze the process of liquefaction and saccharification of starch. It is possible to perform complete hydrolysis of starch by using the fusion product of both linear and debranching thermostable enzymes. This will result in saving energy otherwise needed for cooling before the next enzyme can act on the substrate, if a sequential process is utilized. Recombinant enzyme technology, protein engineering, and enzyme immobilization are powerful tools available to enhance the activity of enzymes, lower the cost of enzyme through large scale production in a heterologous host, increase their thermostability, improve pH stability, enhance their productivity, and hence making it competitive with the chemical processes involved in starch hydrolysis and conversions. This review emphasizes the potential of using biocatalysis for the production of useful industrial products and functional foods from cheap agricultural produce and transgenic plants. Rice was selected as a typical example to illustrate many applications of biocatalysis in converting low-value agricultural produce to high-value commercial food and industrial products. The greatest advantages of using enzymes for food processing and for industrial production of biobased products are their environmental friendliness and consumer acceptance as being a natural process.
TL;DR: The protein profile of mice whole saliva from animals fed on three experimental diets was characterized and compared, and a hypertrophy of parotid salivary gland acini was observed by histology, along with a decrease in body mass in the first 4 days of the experimental period.
Abstract: Tannins are characterized by protein-binding affinity. They have astringent/bitter properties that act as deterrents, affecting diet selection. Two groups of salivary proteins, proline-rich proteins and histatins, are effective precipitators of tannin, decreasing levels of available tannins. The possibility of other salivary proteins having a co-adjuvant role on host defense mechanisms against tannins is unknown. In this work, we characterized and compared the protein profile of mice whole saliva from animals fed on three experimental diets: tannin-free diet, diet with the incorporation of 5% hydrolyzable tannins (tannic acid), or diet with 5% condensed tannins (quebracho). Protein analysis was performed by one-dimensional gel electrophoresis combined with Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectrometry to allow the dynamic study of interactions between diet and saliva. Since abundant salivary proteins obscure the purification and identification of medium and low expressed salivary proteins, we used centrifugation to obtain saliva samples free from proteins that precipitate after tannin binding. Data from Peptide Mass Fingerprinting allowed us to identify ten different proteins, some of them showing more than one isoform. Tannin-enriched diets were observed to change the salivary protein profile. One isoform of α-amylase was overexpressed with both types of tannins. Aldehyde reductase was only identified in saliva of the quebracho group. Additionally, a hypertrophy of parotid salivary gland acini was observed by histology, along with a decrease in body mass in the first 4 days of the experimental period.
TL;DR: Collection by passive drool instead of cotton‐containing devices for amylase determinations is recommended, particularly whenever it is impossible to ensure full, uniform cotton saturation, and azide should be avoided as a preservative.
Abstract: Salivary α-amylase recently has been identified as a stress-related biomarker for autonomic nervous system activity. This study addresses sample collection and handling considerations for field researchers. Saliva was collected by unstimulated passive drool from 14 adults and pooled. Incubation of pooled saliva at 22 or 37°C for 21 days did not diminish amylase activity. However, sodium azide added at concentrations ≤1.12 mg/ml to pooled saliva artificially inflated activity. After dosing cotton rolls within Salivette saliva collection devices with 0.25 to 1.5 ml of unpooled passive drool saliva from six additional adults, recovery of amylase activity was significantly below 100% at all volumes, with increased variance in recovery when the cotton was incompletely saturated (≤1.0 ml). Hence, collection by passive drool instead of cotton-containing devices for amylase determinations is recommended, particularly whenever it is impossible to ensure full, uniform cotton saturation, and azide should be avoided as a preservative. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc.
TL;DR: It is suggested that oral administration of exogenous amylase affected activities of intestinal enzymes and the production of pancreatic digestive enzymes in a dose-dependent manner.
Abstract: Four hundred and forty 1-day-old Arbor Acre broilers were fed commercial starter diets with 0, 250, 750 and 2,250 mg/kg of an alpha-amylase preparation from 1 to 21 days of age to investigate the effects of an exogenous enzyme on growth performance, activities of digestive enzymes in the pancreas and anterior intestinal contents and pancreatic amylase mRNA expression. Body weight gain (BWG) and average daily gain (ADG) increased linearly (p 0.05). The pancreatic protease, trypsin, and lipase were not affected by exogenous amylase levels. Consistent with the tendency for a linear depression of amylase activity, pancreatic α-amylase mRNA was down-regulated by dietary amylase supplementation. The present study suggested that oral administration of exogenous amylase affected activities of intestinal enzymes and the production of pancreatic digestive enzymes in a dose-dependent manner.
TL;DR: Enzymatic oxidation of epicatechin 3-O-gallate produced a similar polymer-like substance and suggested that condensation between a B-ring and galloyl groups was involved in the polymerization reaction.
Abstract: Lipase and amylase inhibitory activities of black tea were examined. After solvent partitioning of a black tea extract with the ethyl acetate and n-butanol, the two soluble fractions showed comparable inhibitory activities. Activity in the ethyl acetate fraction was mainly attributable to polyphenols with low-molecular weights, such as theaflavin gallates. On the other hand, the active substance in the n-butanol layer was ascertained to be a polymer-like substance. 1H- and 13C-NMR spectra showed signals arising from the flavan A-ring and galloyl groups, although signals due to flavan B-rings were not detected, suggesting that the polymer-like substances were generated by oxidative condensation of flavan B-rings, a result which was previously deduced from our results of in vitro catechin oxidation experiments. Enzymatic oxidation of epicatechin 3-O-gallate produced a similar polymer-like substance and suggested that condensation between a B-ring and galloyl groups was involved in the polymerization reaction.
TL;DR: By comparing enzymatic digestion of native maize granules to that of rice granules, it was concluded that the presence of pores in maize granule appeared to significantly affect overall rate of digestion after sufficient reaction time, but not at the very initial stage of hydrolysis.
Abstract: Porcine pancreatic alpha-amylase activity on native starch granules is more accurately described as a function of surface area of the granules rather than of substrate concentration. The apparent K(m) of alpha-amylolysis of native starch from potato, maize, and rice expressed as a function of substrate concentration was largest for potato with a single value of V(max). However, the ratio of the slope of a Lineweaver-Burk plot to that of rice for enzymatic hydrolysis of native potato and maize starch were 7.78 and 2.58, respectively, which were very close to the ratio of surface area per mass of the two starch granules to that of rice. Therefore, the reciprocal of initial velocity was a linear function of the reciprocal of surface area for each starch granule. Surface area was calculated assuming the starch granules were spherical. The values obtained by this calculation were in good agreement with the value obtained by the photomicrographic method. By comparing enzymatic digestion of native maize granules to that of rice granules, it was concluded that the presence of pores in maize granules appeared to significantly affect overall rate of digestion after sufficient reaction time, but not at the very initial stage of hydrolysis.