Showing papers on "Amylase published in 2005"

Carbohydrates in fish nutrition: digestion and absorption in postlarval stages

Abstract: This review summarizes information regarding digestion and absorption of carbohydrates in cultivated fish Relevant results of studies of digestive enzymes, eg amylase, chitinase, cellulase and brush border disaccharidases are presented Fish amylases appear to be molecularly closely related and to have characteristics comparable to mammalian amylases Whether chitinases and cellulases are endogenous enzymes of some fish species is still a matter of speculation, although recent molecular evidence, at least for chitinase seems to settle the issue in favour of endogenous sources Feed and intestinal microbes may be the source of polysaccharidases in fish feeding on nutrients-containing non-starch polysaccharides Knowledge regarding monosaccharide transport in fish intestine as interpreted from studies of brush border membrane vesicles, everted sleeves of fish intestinal sections and molecular biology is discussed Glucose transporters of the intestinal brush border show characteristics similar to those found in mammals A tabulatory presentation of experimental details and results reported in the literature regarding starch digestibility is included as a basis for discussion Although numerous investigations on digestion of starch and other carbohydrates in fish have been published, the existing information is highly fragmentary As yet, it is impossible to derive a cohesive picture on the integrated process of carbohydrate hydrolysis and absorption and interaction with diet composition for any of the fish species under cultivation The physiological mechanisms behind the species differences are not known

Anti-amylase, anti-glucosidase and anti-angiotensin i-converting enzyme potential of selected foods

Abstract: α-Amylase and α-glucosidase have been targeted as potential avenues for modulation of postprandial hyperglycemia through mild inhibition of the enzymatic breakdown of complex carbohydrates to decrease meal-derived glucose absorption. Water-soluble extracts with optimized phenolic content of selected American and Asian foods were investigated for inhibitory activity against α-amylase and α-glucosidase, as well as angiotensin I-converting enzyme (ACE), which has been linked to hyperglycemia-associated hypertension. Porcine pancreatic α-amylase (PPA) was allowed to react with each phenolic-optimized food extract, and the derivatized enzyme-phytochemical mixtures obtained were characterized for residual amylase activity. The α-glucosidase and ACE activities were determined in the presence of each phenolic-optimized food extract. The amylase activity was inhibited more than the glucosidase activity in the presence of these phytochemical extracts, and more so by Asian foods than by American foods. The Asian spice ginger was found to possess strong ACE inhibitory activity in addition to significant anti-amylase activity. The α-amylase enzyme inhibition was positively associated with extract antioxidant activity and negatively with extract protein content. The significance of food-grade, plant-based amylase inhibitors for modulation of carbohydrate breakdown and control of glycemic index of foods in the context of preventing hyperglycemia and diabetes mellitus complications in the long term and ACE inhibitors for modulation of associated hypertension is hypothesized and discussed.

Poly(beta-hydroxybutyrate) production by a moderate halophile, Halomonas boliviensis LC1 using starch hydrolysate as substrate

Abstract: Aim: The objective of the present work was to enable the use of starch hydrolysate, generated by the action of a recombinant maltooligosaccharide forming amylase from Bacillus halodurans LBK 34, as the carbon source for the production of poly-beta- hydroxybutyrate ( PHB) by Halomonas boliviensis LC1. Methods and Results: In this work, different amounts of the alpha- amylase ( Amy 34) were utilized for starch hydrolysis, resulting in the production of mixtures of maltooligosaccharides ( G1 - G6) at varying ratios. The highest PHB accumulation ( 56 wt%) by H. boliviensis cultivated in shake flasks ( with agitation at 160 rev min(-1)) was obtained when 6.4 U ml(-1) of the amylase was used for starch hydrolysis. When H. boliviensis cells were grown in a fermentor with no oxygen limitation the accumulation of PHB was decreased to 35 wt%. Although some improvements in PHB accumulation and cell mass concentration were reached by the addition of peptone and phosphate, respectively, major enhancements were attained when oxygen limitation was induced in the fermentor. Conclusions: Halomonas boliviensis uses preferentially maltose for PHB formation from starch hydrolysate. It is also able to hydrolyse higher sugars if no other simpler carbon source is available but with a significantly lower polymer yield. Furthermore, H. boliviensis is able to adjust its metabolism to oxygen limitation, most probably by directing the excess NAD( P) H to PHB accumulation. Significance and Impact of the Study: There have been no reports related to PHB production amongst the members of the genus Halomonas. The use of a maltooligosaccharide forming alpha- amylase, which is active at a temperature and pH close to that required for growth of H. boliviensis, and the versatility of this bacterium in the selection of the carbon source may provide an attractive alternative for the utilization of starch- derived raw materials.

Characterization of physical properties of flour and starch obtained from gamma-irradiated white rice

Abstract: Physical and structural characteristics of rice flour and starch obtained from gamma-irradiated white rice were determined. Pasting viscosities of the rice flour and starch, analyzed by using a Rapid Visco Analyser, decreased continuously with the increase in irradiation dosage. Differential scanning calorimetry showed that gelatinization onset, peak and conclusion temperatures of rice flour and starch changed slightly but the enthalpy change decreased significantly with increase of irradiation dosage. All irradiated starch displayed an A-type X-ray diffraction pattern like the native starch. Gel permeation chromatography showed that the blue value ratio of the first peak (amylopectin) to the second one (amylose) decreased with the increase of the irradiation dosage. The weight-average molecular weight (M w ) and gyration radius (R z ) of amylopectin analyzed by using HPSEC-MALLS-RI (high-performance size-exclusion chromatography equipped with multiangle laser-light scattering and refractive index detector) decreased gradually from 1.48 x 10 9 (M w ) and 384.1 nm (R z ) of native rice starch to 2.36 × 10 8 (M w ) and 236.8 nm of 9 kGy-irradiated starch. The branch chain-length distribution of amylopectins determined by HPAEC-ENZ-PAD (high-performance anion-exchange chromatography with amyloglucosidase post-column on-line reactor and pulsed amperometric detector) showed that gamma irradiation had no significant effect on the amylopectin branch chains with 13

Involvement of α-Amylase I-1 in Starch Degradation in Rice Chloroplasts

Abstract: To determine the role of alpha-amylase isoform I-1 in the degradation of starch in rice leaf chloroplasts, we generated a series of transgenic rice plants with suppressed expression or overexpression of alpha-amylase I-1. In the lines with suppressed expression of alpha-amylase I-1 at both the mRNA and protein levels, seed germination and seedling growth were markedly delayed in comparison with those in the wild-type plants. However, the growth retardation was overcome by supplementation of sugars. Interestingly, a significant increase of starch accumulation in the young leaf tissues was observed under a sugar-supplemented condition. In contrast, the starch content of leaves was reduced in the plants overexpressing alpha-amylase I-1. In immunocytochemical analysis with specific anti-alpha-amylase I-1 antiserum, immuno-gold particles deposited in the chloroplasts and extracellular space in young leaf cells. We further examined the expression and targeting of alpha-amylase I-1 fused with the green fluorescent protein in re-differentiated green cells, and showed that the fluorescence of the expressed fusion protein co-localized with the chlorophyll autofluorescence in the transgenic cells. In addition, mature protein species of alpha-amylase I-1 bearing an oligosaccharide side chain were detected in the isolated chloroplasts. Based on these results, we concluded that alpha-amylase I-1 targets the chloroplasts through the endoplasmic reticulum-Golgi system and plays a significant role in the starch degradation in rice leaves.

Organic solvent tolerance of halophilic α-amylase from a Haloarchaeon, Haloarcula sp. strain S-1

Abstract: A halophilic archaeon, Haloarcula sp. strain S-1, produced extracellular organic solvent-tolerant alpha-amylase. Molecular mass of the enzyme was estimated to be 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This amylase exhibited maximal activity at 50 degrees C in buffer containing 4.3 M NaCl, pH 7.0. Moreover, the enzyme was active and stable in various organic solvents (benzene, toluene, and chloroform, etc.). Activity was not detected at low ionic strengths, but it was detected in the presence of chloroform at low salt concentrations. On the other hand, no activity was detected in the presence of ethyl alcohol and acetone.

Hydrolysis of raw tuber starches by amylase of Aspergillus niger AM07 isolated from the soil

Abstract: Eight Aspergillus niger strains which produced strong starch degrading amylase were isolated from the soil using a medium containing Remazol Brilliant Blue (RBB) starch as substrate. Amylase production was detected by the disappearance of the blue colour around the colony. Among the isolates, A. niger AM07 produced the largest clear zone (7.0mm) on Remazol Brilliant Blue (RBB) agar plate and also gave the highest amylase yield (806 U/ml) in solid-state fermentation process, hence it was selected for further studies. The crude amylase preparation of A. niger AM07 had temperature and pH optima activities at 60 o C and 4.0 respectively. The optimum substrate concentration was 3 %. The action of the crude amylase of A. niger on raw tuber starches of yam, cassava, sweet potato and cocoyam were studied in comparison with the well known maize starch which is a cereal starch. The crude amylase was able to hydrolyze all the raw starches tested. Hydrolysis was significantly (p<0.05) dependent on starch source and length of incubation. At 72-h incubation time, raw cassava starch gave the highest yield of 200.1 mg/g with a conversion efficiency of 198.91% while raw maize starch gave a yield of 109.6 mg/g with 108.95 % conversion efficiency. Raw cocoyam starch was more resistant to hydrolysis and incubation of cocoyam starch beyond 24 h, resulted in decreased yield of reducing sugars. Thin layer chromatography showed glucose as the main sugar produced with low level of maltose.

Anti-diabetic and anti-hypertensive potential of sprouted and solid-state bioprocessed soybean.

Abstract: Long-term type 2 diabetes can lead to numerous biological complications, such as hypertension and cardio-vascular disease. Key enzymes involved in the enzymatic breakdown of complex carbohydrates,pancreatic alpha-amylase and intestinal alpha-glucosidase, have been targeted as potential avenues for modulation of type 2 diabetes-associated post-prandial hyperglycemia through mild inhibition of their enzymatic activities so as to decrease meal-derived glucose absorption. Further, inhibition of hypertension-linked angiotensin I-converting enzyme (ACE) was targeted as a potential approach for modulation of diabetes-linked hypertension. Water-soluble extracts of soybean optimized for phenolic content via sprouting or bioprocessing by dietary fungus (Rhizopus oligosporus, Lentinus edodes) were investigated for inhibitory activity against porcine pancreatic alpha-amylase (PPA), yeast alpha-glucosidase, and rabbit lung ACE in vitro. PPA was allowed to react with each phenolic-optimized extract and the derivatized enzyme-phytochemical mixtures obtained were characterized for residual amylase activity. Alpha-glucosidase and ACE activities were determined in the presence of each phenolic-optimized extract. All of the soybean extracts possessed marked anti-amylase activity, with extracts of R. oligosporus-bioprocessed soybean having the strongest inhibitory activity, but only slight anti-glucosidase activity. The anti-amylase activity of each extract seemed associated with extract antioxidant activity. Anti-enzyme activity was slightly associated with total soluble phenolic content per se, but seemed more associated to the length of sprouting or bioprocessing of the soybean substrate. Short-term sprouting or bioprocessing seemed to improve anti-amylase activity, while long-term sprouting or bioprocessing seemed to aid anti-glucosidase activity. While ACE activity was strongly inhibited by all of the soybean extracts (44-97%), only sprouting was found to increase this inhibition and bioprocessing of soybean with L. edodes decreased inhibitory activity of soybean extract. The results suggest that sprouting and dietary fungal bioprocessing of soybean improve the anti-diabetic potential of soybean extracts, potentially through modulation of the phenolic profile of the extract, and further suggest that enzyme inhibitory activity may be linked to phenolic antioxidant mobilization during spouting and/ or bioprocessing. The significance of food-grade, plant-based enzyme inhibitors for modulation of carbohydrate breakdown and control of glycemic index of foods in the context of preventing hyperglycemia and diabetes mellitus complications such as hypertension in the long-term is hypothesized and discussed.

Effect of starch on the cariogenic potential of sucrose.

Abstract: Since in vitro and animal studies suggest that the combination of starch with sucrose may be more cariogenic than sucrose alone, the study assessed in situ the effects of this association applied in vitro on the acidogenicity, biochemical and microbiological composition of dental biofilm, as well as on enamel demineralization. During two phases of 14 d each, fifteen volunteers wore palatal appliances containing blocks of human deciduous enamel, which were extra-orally submitted to four groups of treatments: water (negative control, T1); 2 % starch (T2); 10 % sucrose (T3); and 2 % starch+10 % sucrose (T4). The solutions were dripped onto the blocks eight times per day. The biofilm formed on the blocks was analysed with regard to amylase activity, acidogenicity, and biochemical and microbiological composition. Demineralization was determined on enamel by cross-sectional microhardness. The greatest mineral loss was observed for the association starch+sucrose (P<0.05). Also, this association resulted in the highest lactobacillus count in the biofilm formed (P<0.05). In conclusion, the findings suggest that a small amount of added starch increases the cariogenic potential of sucrose.

Raw starch degrading amylase production by mixed culture of Aspergillus niger and Saccharomyces cerevisae grown on sorghum pomace

Abstract: Production of raw starch degrading amylase by a mixed culture of Aspergillus niger and Saccharomyces cerevisae grown on sorghum pomace as nutrient source was investigated. Effect of mineral nutrient supplementation of sorghum pomace on raw starch degrading amylase activity was also determined. Sorghum pomace medium significantly (P Key words: Raw starch, Amylase, Aspergillus niger , Saccharomyces cerevisae , Sorghum pomace. African Journal of Biotechnology Vol. 4 (8), pp. 785-784

Profiling the expression of genes controlling rice grain quality.

Abstract: Rice provides a staple source of energy, protein and other nutrients to half of the world population. Over 90 of the rice seeds consists of starch and protein by dry weight. The quantity and property of starch and protein thus play a dominant role in the yield and quality of rice. The amylase content of starch is a determining factor in the eating and cooking quality while the amount and essential amino acids balance of storage proteins affect the nutritional quality of rice. In China, the super-hybrid rice currently under the last phase of development has a 35 yield advantage over the best inbred rice varieties. However, its grain quality needs further improvement. This study reported the expression patterns of 44 genes participating in starch, storage protein, and lysine synthesis in the developing rice grain. Field grown rice cultivar 9311, the paternal line of an elite super-hybrid rice LYP9with its draft genomic sequence released, was used as plant material. Results revealed diverse yet coordinated expression profiles of the genes involved in the three pathways which lead to the final composition and property of starch, protein and lysine that determine the quality of rice, providing useful information for rice quality improvement.

Should serum pancreatic lipase replace serum amylase as a biomarker of acute pancreatitis

Abstract: Background: Serum pancreatic lipase may improve the diagnosis of pancreatitis compared to serum amylase. Both enzymes have been measured simultaneously at our hospital allowing for a comparison of their diagnostic accuracy. Methods: Seventeen thousand five hundred and thirty-one measurements of either serum amylase and or serum pancreatic lipase were made on 10 931 patients treated at a metropolitan teaching hospital between January 2001 and May 2003. Of these, 8937 were initially treated in the Emergency Department. These results were collected in a database, which was linked by the patients’ medical record number to the radiology and medical records. Patients with either an elevated lipase value or a discharge diagnosis of acute pancreatitis had their radiological diagnosis reviewed along with their biochemistry and histology record. The diagnosis of acute pancreatitis was made if there was radiological evidence of peripancreatic inflammation. Results: One thousand eight hundred and twenty-five patients had either elevated serum amylase and or serum pancreatic lipase. The medical records coded for pancreatitis in a further 55 whose enzymes were not elevated. Three hundred and twenty of these had radiological evidence of acute pancreatitis. Receiver operator characteristic analysis of the initial sample from patients received in the Emergency Department showed improved diagnostic accuracy for serum pancreatic lipase (area under the curve (AUC) 0.948) compared with serum amylase (AUC, 0.906, P < 0.05). A clinically useful cut-off point would be at the diagnostic threshold; 208 U/L (normal <190 U/L) for serum pancreatic lipase and 114 U/L (normal 27–100 U/L) for serum amylase where the sensitivity was 90.3 cf., 76.8% and the specificity was 93 cf., 92.6%. 18.8% of the acute pancreatitis patients did not have elevated serum amylase while only 2.9% did not have elevated serum pancreatic lipase on the first emergency department measurement. Conclusion: It is concluded that serum pancreatic lipase is a more accurate biomarker of acute pancreatitis than serum amylase.

Biochemical characterization of α‐amylase of the Sunn pest, Eurygaster integriceps

Abstract: The α-amylase in the midgut and salivary glands of Eurygaster integriceps was isolated and characterized. The specific activity of α-amylase in the midgut was 1.77 U/mg protein and in the salivary glands was 1.65 U/mg protein. Sodium dodecylsulfate electrophoresis showed that both midgut and salivary glands contain isozymes. Only a trace amount of α-amylase activity was detected in the first nymphal stage (0.19 U/mg protein), whereas α-amylase activity was highest in the third nymphal stage (1.21 U/mg protein). The results show that α-amylase activity in the immature stages increase constantly to the third instar stage. There was no significant difference in enzyme activity between the third, fourth and fifth nymphal stages and adults. The optimum pH and temperature for the enzyme activity was determined to be 6.5 and 35°C, respectively. The enzyme activity was inhibited by addition of ethylenediaminetetraacetic acid, urea, sodium dodecylsulfate and Mg2+, but NaCl and KCl enhanced enzyme activity.

Digestive enzyme response to supplemental ingredients in practical diets for juvenile freshwater crayfish Cherax quadricarinatus

Abstract: A feeding trial was conducted to determine digestive enzyme activity in Cherax quadricarinatus in response to diet composition. Eight experimental diets, each containing one of squid, red crab, sardine (600 and 650 g kg )1 crude protein), sorghum, wheat meal, soy paste and the reference diet were evaluated over 30 days in terms of amylase, lipase, and protease activities in the hepatopancreas. The diet containing wheat meal produced the highest amylase activity. Lipase activity was not significantly different among treatments. Protease activity was higher in animals fed fish meal (60 g kg )1 protein), soy paste and reference diet. Results suggest that C. quadricarinatus can modify hepatopancreatic enzyme levels in response to different compounds in the diet and can digest a broad variety of ingredients, particularly starch.

A rapid response of β-amylase to nitric oxide but not gibberellin in wheat seeds during the early stage of germination

Abstract: The effects of nitric oxide (NO) and gibberellic acid (GA3) on the responses of amylases in wheat (Triticum aestivum L.) seeds (caryopses) were investigated during the first 12 h of germination. GA3 had no effects on the activities of α-amylase (EC 3.2.1.1) or β-amylase (EC 3.2.1.2), either in intact seeds or embryoless halves within 12 h. In contrast, addition of sodium nitroprusside (SNP), an NO donor, was able to induce a rapid increase in β-amylase activity without affecting α-amylase. Furthermore, the rapid response of β-amylase to SNP in wheat seeds could be attributed to NO and was approximately dose-dependent. Some other aspects of SNP induction of amylase isozymes were also characterized. Further investigations showed that SNP might play an interesting role in the dissociation of free β-amylase from small homopolymers or heteropolymers. Furthermore, SNP also directly induced the release of bound β-amylase from glutenin and its crude enzyme preparation. However, the slight increase in protease also induced by SNP might not be responsible for this action. Interestingly, based on the fact that the rapid response of β-amylase to NO also existed in seeds of other species, such as barley, soybean, rice and watermelon, it might be a universal event in early seed germination.

Enzyme production by endophytes of Brucea javanica

Abstract: Twenty-one endophytic isolates from Brucea javanica were tested for their ability to produce extracellular cellulase and extracellular and intracellular amylase, ligninase, pectinase and xylanase. The same fungi were tested for their ability to cause weight loss in wood blocks. All fungi produced amylase and cellulase, while only one sterile mycelium produced ligninase and no isolates produced pectinase. The enzyme tests indicate that most endophytes are degraders of the simpler sugars and cellulose available in recently dead leaves and possibly wood. Only one slow growing species of sterile mycelium however, appeared to be capable of degrading lignin that would be available in dead wood. No fungi appeared to be latent pathogens. A discussion of enzyme production in relation to possible roles of endophytes is provided.

Effects of Temperature and Sodium Chloride Concentration on the Activities of Proteases and Amylases in Soy Sauce Koji

Abstract: This study investigated the effects of temperature and sodium chloride concentration on the proteolytic and amylolytic activities of soy sauce koji. The optimal temperatures for both protease and amylase were found in the range of 50-55 degrees C. The protease was not stable at 55 degrees C and retained only approximately 20% residual activity after incubation at 55 degrees C for 4 h. The protease was labile in sodium chloride solution, whereas the amylase was quite stable. The residual protease activity in an 18% NaCl solution was only approximately 3%. The harvested koji was mixed with 1.5 volumes of water (v/w) and incubated at 45 degrees C for 48 h; the total nitrogen and amino nitrogen contents were 1.3 and 0.56%, respectively. The results indicated that the hydrolysis of koji at the critical temperature of 45 degrees C could be employed as a rapid fermentation method to reduce the time for soy sauce manufacturing. According to this study, the combination of 5% sodium chloride and fermentation at 45 degrees C was considered as the best condition for the prohydrolysis of koji for making soy sauce. In addition, the critical temperature of 45 degrees C was very important when used in the preparation of protein hydrolysates for the flavoring industry and for the preparation of biologically active peptides.