Showing papers on "Amylase published in 2016"

Intactness of cell wall structure controls the in vitro digestion of starch in legumes

Abstract: Increasing the level of starch that is not digested by the end of the small intestine and therefore enters the colon (‘resistant starch’) is a major opportunity for improving the nutritional profile of foods. One mechanism that has been shown to be successful is entrapment of starch within an intact plant tissue structure. However, the level of tissue intactness required for resistance to amylase digestion has not been defined. In this study, intact cells were isolated from a range of legumes after thermal treatment at 60 °C (starch not gelatinised) or 95 °C (starch gelatinised) followed by hydrolysis using pancreatic alpha amylase. It was found that intact cells, isolated at either temperature, were impervious to amylase. However, application of mechanical force damaged the cell wall and made starch accessible to digestive enzymes. This shows that the access of enzymes to the entrapped swollen starch is the rate limiting step controlling hydrolysis of starch in cooked legumes. The results suggest that a single cell wall could be sufficient to provide an effective delivery of starch to the large intestine with consequent nutritional benefits, provided that mechanical damage during digestion is avoided.

β-amylase 1 (BAM1) degrades transitory starch to sustain proline biosynthesis during drought stress

Abstract: During photosynthesis of higher plants, absorbed light energy is converted into chemical energy that, in part, is accumulated in the form of transitory starch within chloroplasts. In the following night, transitory starch is mobilized to sustain the heterotrophic metabolism of the plant. β-amylases are glucan hydrolases that cleave α-1,4-glycosidic bonds of starch and release maltose units from the non-reducing end of the polysaccharide chain. In Arabidopsis, nocturnal degradation of transitory starch involves mainly β-amylase-3 (BAM3). A second β-amylase isoform, β-amylase-1 (BAM1), is involved in diurnal starch degradation in guard cells, a process that sustains stomata opening. However, BAM1 also contributes to diurnal starch turnover in mesophyll cells under osmotic stress. With the aim of dissecting the role of β-amylases in osmotic stress responses in Arabidopsis, mutant plants lacking either BAM1 or BAM3 were subject to a mild (150mM mannitol) and prolonged (up to one week) osmotic stress. We show here that leaves of osmotically-stressed bam1 plants accumulated more starch and fewer soluble sugars than both wild-type and bam3 plants during the day. Moreover, bam1 mutants were impaired in proline accumulation and suffered from stronger lipid peroxidation, compared with both wild-type and bam3 plants. Taken together, these data strongly suggest that carbon skeletons deriving from BAM1 diurnal degradation of transitory starch support the biosynthesis of proline required to face the osmotic stress. We propose the transitory-starch/proline interplay as an interesting trait to be tackled by breeding technologies aimingto improve drought tolerance in relevant crops.

In vitro and in vivo α-amylase and α-glucosidase inhibiting activities of the protein extracts from two varieties of bitter gourd ( Momordica charantia L.)

Abstract: α-amylase and α-glucosidase digest the carbohydrates and increase the postprandial glucose level in diabetic patients. Inhibiting the activity of these two enzymes can control postprandial hyperglycemia, and reduce the risk of developing diabetes. Bitter gourd or balsam pear is one of the important medicinal plants used for controlling postprandial hyperglycemia in diabetes patients. However, there is limited information available on the presence of α-amylase and α-glucosidase inhibiting compounds. In the current study, the protein extracts from the fruits of M. charantia var. charantia (MCC) and M. charantia var. muricata (MCM) were tested for α-amylase and α-glucosidase inhibiting activities in vitro, and glucose lowering activity after oral administration in vivo. The protein extract from both MCC and MCM inhibited the activity of α-amylase and α-glucosidase through competitive inhibition, which was on par with Acarbose as indicated by in vitro percentage of inhibition (66 to 69 %) and IC50 (0.26 to 0.29 mg/ml). Both the protein extracts significantly reduced peak blood glucose and area under the curve in Streptozotocin-induced diabetic rats, which were orally challenged with starch and sucrose. Protein extracts from the fruits of the two varieties of bitter gourd inhibited α-amylase and α-glucosidase in vitro and lowered the blood glucose level in vivo on par with Acarbose when orally administrated to Streptozotocin-induced diabetic rats. Further studies on mechanism of action and methods of safe and biologically active delivery will help to develop an anti-diabetic oral protein drug from these plants.

Salivary Amylase: Digestion and Metabolic Syndrome.

Abstract: Salivary amylase is a glucose-polymer cleavage enzyme that is produced by the salivary glands. It comprises a small portion of the total amylase excreted, which is mostly made by the pancreas. Amylases digest starch into smaller molecules, ultimately yielding maltose, which in turn is cleaved into two glucose molecules by maltase. Starch comprises a significant portion of the typical human diet for most nationalities. Given that salivary amylase is such a small portion of total amylase, it is unclear why it exists and whether it conveys an evolutionary advantage when ingesting starch. This review will consider the impact of salivary amylase on oral perception, nutrient signaling, anticipatory metabolic reflexes, blood sugar, and its clinical implications for preventing metabolic syndrome and obesity.

Screening and characterization of amylase and cellulase activities in psychrotolerant yeasts.

Abstract: Amylases and cellulases have great potential for application in industries such as food, detergent, laundry, textile, baking and biofuels. A common requirement in these fields is to reduce the temperatures of the processes, leading to a continuous search for microorganisms that secrete cold-active amylases and cellulases. Psychrotolerant yeasts are good candidates because they inhabit cold-environments. In this work, we analyzed the ability of yeasts isolated from the Antarctic region to grow on starch or carboxymethylcellulose, and their potential extracellular amylases and cellulases. All tested yeasts were able to grow with soluble starch or carboxymethylcellulose as the sole carbon source; however, not all of them produced ethanol by fermentation of these carbon sources. For the majority of the yeast species, the extracellular amylase or cellulase activity was higher when cultured in medium supplemented with glucose rather than with soluble starch or carboxymethylcellulose. Additionally, higher amylase activities were observed when tested at pH 5.4 and 6.2, and at 30–37 °C, except for Rhodotorula glacialis that showed elevated activity at 10–22 °C. In general, cellulase activity was high until pH 6.2 and between 22–37 °C, while the sample from Mrakia blollopis showed high activity at 4–22 °C. Peptide mass fingerprinting analysis of a potential amylase from Tetracladium sp. of about 70 kDa, showed several peptides with positive matches with glucoamylases from other fungi. Almost all yeast species showed extracellular amylase or cellulase activity, and an inducing effect by the respective substrate was observed in a minor number of yeasts. These enzymatic activities were higher at 30 °C in most yeast, with highest amylase and cellulase activity in Tetracladium sp. and M. gelida, respectively. However, Rh. glacialis and M. blollopis displayed high amylase or cellulase activity, respectively, under 22 °C. In this sense, these yeasts are interesting candidates for industrial processes that require lower temperatures.

Rice bran protein hydrolysates exhibit strong in vitro α-amylase, β-glucosidase and ACE-inhibition activities

Abstract: BACKGROUND The objective of this study was to systematically examine the in vitro health-promotion activities of rice bran protein hydrolysates. Rice bran proteins were fractioned into albumin, globulin, prolamin and glutelin, which were subjected to hydrolysis by four protease preparations, namely Alcalase, Neutrase, Flavourzyme and Protamax, and the inhibitory activities of the hydrolysates against α-amylase, α-glucosidase and angiotensin converting enzyme (ACE), were monitored over a hydrolysis period of 240 min. Active peptides in the hydrolysates were isolated by ultra-filtration and ion-exchange chromatography and the peptide sequences of the active fractions were identified by LC-MS/MS. RESULTS Hydrolysis of the proteins resulted in significant increases in these bioactivities, which were generally correlated with the degree of protein hydrolysis. In general, the highest bioactivities were found with albumin and glutelin hydrolysates, followed by globulin hydrolysates, while prolamin hydrolysates showed the lowest activities. Of the four enzymes used, Alcalase- and Protamax-catalysed hydrolysates generally had the highest activities while Flavourzyme-produced hydrolysates had the lowest activity. The MW < 3 kDa fraction of the Alcalase-catalysed glutelin hydrolysates had the highest β-glucosidase inhibition activity, which was identified to contain 13 peptides with six to 32 amino acid residues. CONCLUSION The α-amylase and α-glucosidase inhibitory activities of albumin and glutelin hydrolysates produced by Alcalase and Protamax were comparable in magnitude to those of the standard anti-diabetic drug acarbose, and had the potential to be developed into a dietary or nutraceutical supplement for the management of diabetes. © 2015 Society of Chemical Industry

Taste cell-expressed α-glucosidase enzymes contribute to gustatory responses to disaccharides

Abstract: The primary sweet sensor in mammalian taste cells for sugars and noncaloric sweeteners is the heteromeric combination of type 1 taste receptors 2 and 3 (T1R2+T1R3, encoded by Tas1r2 and Tas1r3 genes) However, in the absence of T1R2+T1R3 (eg, in Tas1r3 KO mice), animals still respond to sugars, arguing for the presence of T1R-independent detection mechanism(s) Our previous findings that several glucose transporters (GLUTs), sodium glucose cotransporter 1 (SGLT1), and the ATP-gated K(+) (KATP) metabolic sensor are preferentially expressed in the same taste cells with T1R3 provides a potential explanation for the T1R-independent detection of sugars: sweet-responsive taste cells that respond to sugars and sweeteners may contain a T1R-dependent (T1R2+T1R3) sweet-sensing pathway for detecting sugars and noncaloric sweeteners, as well as a T1R-independent (GLUTs, SGLT1, KATP) pathway for detecting monosaccharides However, the T1R-independent pathway would not explain responses to disaccharide and oligomeric sugars, such as sucrose, maltose, and maltotriose, which are not substrates for GLUTs or SGLT1 Using RT-PCR, quantitative PCR, in situ hybridization, and immunohistochemistry, we found that taste cells express multiple α-glycosidases (eg, amylase and neutral α glucosidase C) and so-called intestinal "brush border" disaccharide-hydrolyzing enzymes (eg, maltase-glucoamylase and sucrase-isomaltase) Treating the tongue with inhibitors of disaccharidases specifically decreased gustatory nerve responses to disaccharides, but not to monosaccharides or noncaloric sweeteners, indicating that lingual disaccharidases are functional These taste cell-expressed enzymes may locally break down dietary disaccharides and starch hydrolysis products into monosaccharides that could serve as substrates for the T1R-independent sugar sensing pathways

A novel α-amylase-lipase formulation as anti-staling agent in durum wheat bread

Abstract: The aim of this work has been to evaluate the anti-staling effect exerted by a novel α-amylase-lipase enzyme formulation on durum wheat bread, in comparison with four different commercial amylase preparations and with control without added enzymes Bread-making trials were carried out at industrial level Sliced bread, packed under modified atmosphere, was analyzed for texture profile, moisture content, and water activity during 90 days Crumb sections were submitted to environmental scanning electron microscopy at the end of the storage period The α-amylase-lipase enzyme preparation showed synergistic interactions in preventing staling In particular, bread added of these two enzymes in mixture was always softer and more chewable than either control or samples added of other enzymes Moreover, α-amylase-lipase exhibited the most marked effect in slowing down both hardening and chewiness changes during time Starting from 7 days of storage, both water activity and moisture content of bread added of α-amylase-lipase were higher than in control Starting from 68 days the moisture content of α-amylase-lipase-added bread became lower than that of other enzyme-added breads, and at the end of storage also water activity was significantly lower Pore morphology of α-amylase-lipase-added bread appeared markedly different from that of control bread

Effects of tea polyphenols and different teas on pancreatic α-amylase activity in vitro

Abstract: The effects of tea polyphenols (TP) and different types of teas (green, black and oolong tea) processed from the same fresh leaves on pancreatic α-amylase activity were studied using potato starch and cooked potato as substrates. The results showed that, with the both substrates, low concentration of TP significantly increased α-amylase activity while high concentration inhibited it by non-competitive fashion. In addition, the extents of enzymatic activation and inhibition were different when TP was pre-incubated with α-amylase or starch, respectively. The interaction of TP with enzyme/starch led to decreased antioxidant capacity. Results also showed that all the three types of teas significantly enhanced α-amylase activity for a wide range of concentrations (0.34–27.14 mg/mL), and green tea showed the highest activation effect. It is concluded that high concentration of TP exhibits mild inhibitory effect against α-amylase, while green tea, black tea and oolong tea enhance α-amylase activity, which may be due to other constituents in the tea, enhancing α-amylase activity that counteracts the inhibitory effect of TP.

Modulation of growth performances, survival, digestive enzyme activities and intestinal microbiota in common carp (Cyprinus carpio) larvae using short chain fructooligosaccharide

Abstract: This study investigates the effects of inclusion of low levels of dietary short chain fructooligosacchairde (sc-FOS) on physiological response and intestinal microbiota of carp (Cyprinus carpio) larvae. After acclimation, fish (550 ± 20 mg) were allocated into nine tanks (40 fish per tank) and triplicate groups were fed a control diet (0%) or diets containing 0.5% and 1% sc-FOS for 7 weeks. At the end of the experiment, the growth performance parameters (final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) and condition factor (CF), survival rate as well as digestive enzyme activities (amylase, lipase and protease), total viable counts of heterotrophic aerobic bacteria (TVC) and lactic acid bacteria (LAB) level in intestinal microbiota were measured. Our results revealed no significant (P > 0.05) effects of sc-FOS on growth performance and TVC when compared with the control group. However, administration of low levels of dietary sc-FOS significantly increased digestive enzyme activities (lipase and amylase) and LAB levels (P < 0.05). Also, survival rate was significantly elevated in sc-FOS fed carp. These results revealed that administration of low levels of sc-FOS can be considered as a beneficial dietary supplement for larval stage of common carp.

Heterocyclic Compounds: Effective α-Amylase and α-Glucosidase Inhibitors.

Abstract: Diabetes Mellitus (DM) is a metabolic disease characterized by high blood sugar levels. Recently, it has emerged as an important and global health problem with long-term complications and high economic burden. α-Amylase (α-Amy) and α-glucosidase (α-Gls) are two enzymes which are involved in the hydrolysis of starch into sugars and disaccharides leading to the increase of blood glucose level. Hence, inhibition of α-amylase and α-glucosidase plays key role in the treatment of type 2 diabetes. Heterocyclic compounds -both synthetic and naturally occurring derivatives- possess efficient biological properties. At this juncture, they have demonstrated potent inhibitory activity against α-Amy and α-Gls and were found to be versatile tools for the development of novel anti-diabetic agents.

Dry-grind processing using amylase corn and superior yeast to reduce the exogenous enzyme requirements in bioethanol production.

Abstract: Conventional corn dry-grind ethanol production process requires exogenous alpha and glucoamylases enzymes to breakdown starch into glucose, which is fermented to ethanol by yeast. This study evaluates the potential use of new genetically engineered corn and yeast, which can eliminate or minimize the use of these external enzymes, improve the economics and process efficiencies, and simplify the process. An approach of in situ ethanol removal during fermentation was also investigated for its potential to improve the efficiency of high-solid fermentation, which can significantly reduce the downstream ethanol and co-product recovery cost. The fermentation of amylase corn (producing endogenous α-amylase) using conventional yeast and no addition of exogenous α-amylase resulted in ethanol concentration of 4.1 % higher compared to control treatment (conventional corn using exogenous α-amylase). Conventional corn processed with exogenous α-amylase and superior yeast (producing glucoamylase or GA) with no exogenous glucoamylase addition resulted in ethanol concentration similar to control treatment (conventional yeast with exogenous glucoamylase addition). Combination of amylase corn and superior yeast required only 25 % of recommended glucoamylase dose to complete fermentation and achieve ethanol concentration and yield similar to control treatment (conventional corn with exogenous α-amylase, conventional yeast with exogenous glucoamylase). Use of superior yeast with 50 % GA addition resulted in similar increases in yield for conventional or amylase corn of approximately 7 % compared to that of control treatment. Combination of amylase corn, superior yeast, and in situ ethanol removal resulted in a process that allowed complete fermentation of 40 % slurry solids with only 50 % of exogenous GA enzyme requirements and 64.6 % higher ethanol yield compared to that of conventional process. Use of amylase corn and superior yeast in the dry-grind processing industry can reduce the total external enzyme usage by more than 80 %, and combining their use with in situ removal of ethanol during fermentation allows efficient high-solid fermentation.

Low serum amylase and obesity, diabetes and metabolic syndrome: A novel interpretation

Abstract: For the last decade, low serum amylase (hypoamylasemia) has been reported in certain common cardiometabolic conditions such as obesity, diabetes (regardless of type), and metabolic syndrome, all of which appear to have a common etiology of insufficient insulin action due to insulin resistance and/or diminished insulin secretion. Some clinical studies have shown that salivary amylase may be preferentially decreased in obese individuals, whereas others have revealed that pancreatic amylase may be preferentially decreased in diabetic subjects with insulin dependence. Despite this accumulated evidence, the clinical relevance of serum, salivary, and pancreatic amylase and the underlying mechanisms have not been fully elucidated. In recent years, copy number variations (CNVs) in the salivary amylase gene (AMY1), which range more broadly than the pancreatic amylase gene (AMY2A and AMY2B), have been shown to be well correlated with salivary and serum amylase levels. In addition, low CNV of AMY1, indicating low salivary amylase, was associated with insulin resistance, obesity, low taste perception/satiety, and postprandial hyperglycemia through impaired insulin secretion at early cephalic phase. In most populations, insulin-dependent diabetes is less prevalent (minor contribution) compared with insulin-independent diabetes, and obesity is highly prevalent compared with low body weight. Therefore, obesity as a condition that elicits cardiometabolic diseases relating to insulin resistance (major contribution) may be a common determinant for low serum amylase in a general population. In this review, the novel interpretation of low serum, salivary, and pancreas amylase is discussed in terms of major contributions of obesity, diabetes, and metabolic syndrome.

Long term enhanced solid-state fermentation: Inoculation strategies for amylase production from soy and bread wastes by Thermomyces sp. in a sequential batch operation

Abstract: The effect of two thermophilic amylase producing strains was evaluated using different mixtures of soy and bread wastes. Thermomyces sp. was found to be better inoculum than Geobacillus sp. for a soy and bread waste mixture (90:10 w/w respectively) producing a maximum enzyme activity of 39.9·103 U g−1 dry substrate. Three strategies (a, b, c) were evaluated for solid-state fermentation (SSF) operation in sequential batches. Fermented solids from each batch were used to inoculate the following batch: (a) solids at the moment of maximum biological activity; (b) final solids (end of the process, maximum amylase production); (c) final solids after enzymatic extraction. The evaluated strategies led to an increase in amylase production of 50, 500 and 98% for each strategy, respectively. This indicates the suitability of fermented solids to act as inoculum and the enhancement of amylase production compared to traditional batches. As one of the main challenges of SSF is the maintenance of a productive process along time, these results confirm SSF as an excellent option to produce amylases from organic wastes.

Effect of native starch granule size on susceptibility to amylase hydrolysis

Abstract: The dimensions of native starch granules are critical with respect to controlling digestion by amylase. In general, small starch granules are digested faster than large granules. This mini review considers how the surface area to volume ratio of unprocessed starch granules controls amylase access to the α-glucans and the consequence in terms of ease of depolymerisation. This article is one of three mini reviews considering how native starch granule hydrolysis is regulated by (i) size, (ii) composition, (iii) annealing and heat–moisture treatments.