Showing papers on "Amylase published in 1985"
TL;DR: This study supports the view that human digestive enzymes do not break down dietary NSP and identifies a fraction of starch, RS, present in processed food which resists breakdown by alpha-amylase both in vitro and in the small intestine of man.
451 citations
TL;DR: An improved method for the determination of starch by sequential hydrolysis with thermostable bacterial α-amylase and fungal amyloglucosidase is described in this article.
Abstract: An improved method for the determination of starch by sequential hydrolysis with thermostable bacterial α-amylase and fungal amyloglucosidase is described. Glucose was determined colorimetrically by a glucose oxidase-peroxidase-chromogen system at pH 7. Native normal and waxy starches, and distarch phosphate, gave quantitative yields of glucose with a high degree of precision (coefficient of variation less than 1%). Acetylated distarch phosphate, high-amylose starch and retrograded amylose were initially treated with 1M NaOH for 30 min, then neutralised and analysed successfully as normal starch. Oxidised starch did not give a quantitative yield of glucose because of the presence of dicarboxylic groups in the polymer. For samples containing normal and waxy starch the analysis was carried out in about 4 h. The method was applied to a range of starch-containing foodstuffs and the results are reported.
358 citations
TL;DR: The data indicate, therefore, that glucocorticoids induce a more highly differentiated phenotype in AR42J pancreatic cells, and they suggest that glucoprecipitationoids act via the enhanced transcription of specific mRNAs for acinar cell proteins.
Abstract: Previous studies have suggested a role for glucocorticoids in the differentiation of the acinar pancreas. We have now used the rat tumor cell line AR42J, derived from the acinar pancreas, to directly study this effect of glucocorticoids in vitro. The steroid hormones dexamethasone, corticosterone, aldosterone, and progesterone, but not estrogen, increased both the amylase content and the number of secretory granules of these cells. The potencies of the steroids were directly related to their effectiveness as glucocorticoids; dexamethasone was the most potent hormone and gave maximal effects at 100 nM. Morphometric analyses revealed that dexamethasone increased the volume density of granules 5.5-fold from 0.20 +/- 0.08 to 1.10 +/- 0.20% (n = 4) of the cytoplasmic volume. Dexamethasone treatment also increased the volume density of rough endoplasmic reticulum 2.4-fold from 1.20 +/- 0.09 to 2.86 +/- 0.30% (n = 5) of the cytoplasmic volume. After 48 h of dexamethasone treatment the cellular content of amylase increase eightfold from 2.8 +/- 0.4 to 22.6 +/- 3.8 U/mg protein (n = 6). This effect of dexamethasone was discernible after 12 h of incubation and approached maximal stimulation after 72 h of incubation. The increases in cellular amylase content were due to increased amylase synthesis as shown by specific immunoprecipitation of [35S]methionine-labeled proteins. Moreover, in vitro translation of cellular mRNA indicated that dexamethasone treatment increased amylase mRNA. Dexamethasone treatment also led to increased secretion of amylase in response to the secretagogue cholecystokinin. These data indicate, therefore, that glucocorticoids induce a more highly differentiated phenotype in AR42J pancreatic cells, and they suggest that glucocorticoids act via the enhanced transcription of specific mRNAs for acinar cell proteins.
227 citations
TL;DR: Embryonic villi are stimulated by transfer activity, and their growth depends on enterocytes arising from the crypt, but they appear to be specialized for maternal immunoglobin transfer in ovo.
Abstract: Starch is the main carbohydrate in the food of poultry. Starch granules are digested by pancreatic alpha-amylase in the small intestine. Intestinal villi have enterocytes that project microvilli with a fibrous glycocalyx from the surface. These fine structures are envisaged to entrap water that is mixed with mucin from nearby goblet cells to form the "unstirred water layer." Maltose, maltotriose and alpha-limit dextrins must diffuse across this first barrier to absorption to be hydrolyzed by maltase and sucrase-isomaltase immobilized at the membrane; however, the resultant glucose, once formed, accrues at the surface to provide a concentration advantage. Fowl adjust to changes in dietary starch by altering the amount of amylase released, intestinal surface area and enterocyte carbohydrase concentration. Enterocytes arising during embryonic development have no carbohydrases and are not involved with glucose absorption, but they appear to be specialized for maternal immunoglobin transfer in ovo. Embryonic villi are stimulated by transfer activity, and their growth depends on enterocytes arising from the crypt. Mature crypt cells are capable of digestion-absorptive activities and dominate the villus shortly after the chick hatches when yolk sac reserves are depleted.
167 citations
TL;DR: The enzyme was inhibited by p-chloromercuribenzoate, Cu, and Hg; however, alpha- and beta-cyclodextrins were not competitive inhibitors and the enzyme was active and stable in the presence of air or 10% (vol/vol) ethanol.
Abstract: Clostridium thermosulfurogenes, an anaerobic bacterium which ferments starch into ethanol at 62°C, produced an active extracellular amylase and contained intracellular glucoamylase but not pullulanase activity. The extracellular amylase was purified 2.4-fold, and its general physicochemical and catalytic properties were examined. The extracellular amylase was characterized as a β-amylase (1,4-α-d-glucan maltohydrolase) based on demonstration of exocleavage activity and the production of maltose with a β-anomeric configuration from starch. The β-amylase activity was stable and optimally active at 80 and 75°C, respectively. The pH optimum for activity and the pH stability range was 5.5 to 6 and 3.5 to 6.5, respectively. The apparent [S]0.5V and Vmax for β-amylase activity on starch was 1 mg/ml and 60 U/mg of protein. Similar to described β-amylase, the enzyme was inhibited by p-chloromercuribenzoate, Cu2+, and Hg2+; however, α- and β-cyclodextrins were not competitive inhibitors. The β-amylase was active and stable in the presence of air or 10% (vol/vol) ethanol. The β-amylase and glucoamylase activities enabled the organism to actively ferment raw starch in the absence of significant pullulanase or α-amylase activity.
131 citations
TL;DR: It is concluded that commercial amylase inhibitors failed to decrease starch digestion in vivo mainly because they have insufficient antiamylase activity, however, a partially purified inhibitor with increased specific activity is stable in human gastrointestinal secretions, slows dietary starch ingestion in vitro, rapidly inactivates amylases in the human intestinal lumen, and, at acceptable oral doses, may decrease intraluminal digestion of starch in humans.
125 citations
TL;DR: The study determined the components degraded during a 150-day incubation at 22 degrees C, the apparent vegetative growth pattern, the likely growth-limiting nutrient, and assays that can be used to study key extracellular enzymes.
Abstract: Although the commercially important mushroom Lentinus (= Lentinula) edodes (Berk.) Sing. can be rapidly cultivated on supplemented wood particles, fruiting is not reliable. This study addressed the problem by developing more information about growth and development on a practical oakwood-oatmeal medium. The study determined (i) the components degraded during a 150-day incubation at 22 degrees C, (ii) the apparent vegetative growth pattern, (iii) the likely growth-limiting nutrient, and (iv) assays that can be used to study key extracellular enzymes. All major components of the medium were degraded, lignin selectively so. The vegetative growth rate was most rapid during the initial 90 days, during which weight loss correlated with glucosamine accumulation (assayed after acid hydrolysis). The rate then slowed; in apparent preparation for fruiting, the cultures rapidly accumulated glucosamine (or its oligomer or polymer). Nitrogen was growth limiting. Certain enzyme activities were associated with the pattern of medium degradation, with growth, or with development. They included cellulolytic system enzymes, hemicellulases, the ligninolytic system, (gluco-)amylase, pectinase, acid protease, cell wall lytic enzymes (laminarinase, 1,4-beta-d-glucosidase, beta-N-acetyl-d-glucosaminidase, alpha-d-galactosidase, beta-d-mannosidase), acid phosphatase, and laccase. Enzyme activities over the 150-day incubation period with and without a fruiting stimulus are reported. These results provide a basis for future investigations into the physiology and biochemistry of growth and fruiting.
125 citations
TL;DR: The amino acid sequence deduced from the alpha-amylase gene was fairly homologous with that of another thermostable amylase from Bacillus amyloliquefaciens, and therefore the NH2-terminal portion of the gene encodes 34 amino acid residues as a signal peptide.
Abstract: The nucleotide sequence of the Bacillus stearothermophilus alpha-amylase gene and its flanking regions was determined. An open reading frame was found, comprising a total of 1,647 base pairs (549 amino acids) and starting from a GUG codon as methionine. It was shown by NH2-terminal amino acid sequence analysis that the extracellular amylase consisted of 515 amino acid residues, which corresponded to a molecular weight of 58,779. Thus the NH2-terminal portion of the gene encodes 34 amino acid residues as a signal peptide. The amino acid sequence deduced from the alpha-amylase gene was fairly homologous (61%) with that of another thermostable amylase from Bacillus amyloliquefaciens.
122 citations
TL;DR: The purpose of this article is to review recent literature on the isoenzymes of alpha amylase to bring together findings that may be of interest to clinical laboratory physicians and scientists.
Abstract: The purpose of this article is to review recent literature on the isoenzymes of alpha amylase. Although some studies are cited from the literature of fields other than clinical biochemistry, the aim is to bring together findings that may be of interest to clinical laboratory physicians and scientists. It is hoped that this will be useful in suggesting further studies of amylase. To this end, the review is more selective than exhaustive. The review will discuss the history and chemistry alpha amylases, the measurement of amylase and amylase isoenzymes, posttranslational modifications of human amylases, and the genetics of human pancreatic and salivary amylases. Finally, we will discuss other tissue sources of amylase with emphasis on "genital" amylases and their relationship to the amylase found in serous ovarian tumors.
115 citations
TL;DR: The finding that less than 5% of the total amylase, cellobiase, maltase and trypsin are excreted, after a time identical to the passage time of the food bolus, leads to the proposal that there exists an endo-ectoperitrophic circulation of enzymes by which these enzymes are recovered from the undigested food before it is excreting.
92 citations
TL;DR: It is shown that insulin stimulates both growth and amylase synthesis of AR42J cells, a rat cell line that is derived from a transplantable tumor of the acinar pancreas, and that insulin induced a selective increase of amyl enzyme synthesis over general protein synthesis.
Abstract: Previous in vivo studies have suggested a long-term regulatory role for insulin in the exocrine pancreas. To directly study the long-term effects of insulin on the pancreas in vitro, we have used cultured AR42J cells, a rat cell line that is derived from a transplantable tumor of the acinar pancreas. Hormone-binding experiments with 125I-labeled hormones indicated that AR42J cells have insulin receptors, relatively fewer receptors for insulin-like growth factor II (IGF-II), and no detectable receptors for insulin-like growth factor I (IGF-I). Insulin at concentrations as low as 1 nM stimulated the growth of these cells, as measured by an increase in DNA and protein content, and in cell number. At 100 nM, where insulin had a maximal effect, the growth of AR42J cells was stimulated by 46.1 +/- 10.9% (mean +/- SEM, N = 11). Insulin increased the amylase activity of AR42J cells over the same concentration range that it stimulated growth; at 100 nM, insulin increased amylase by 91.0 +/- 15.4% (mean +/- SEM, N = 23). Immunoprecipitation of [35S]methionine-labeled proteins revealed that insulin induced a selective increase of amylase synthesis over general protein synthesis. These studies indicate, therefore, that insulin stimulates both growth and amylase synthesis of AR42J cells.
TL;DR: It is suggested that complete activation of amylase secretion from the pancreas requires stimulation of both Ca2+-dependent and protein kinase C-activated pathways.
Abstract: Both protein kinase C and Ca2+ may act in concert to bring about activation of secretion. This study examined the actions on pancreatic acini of ionomycin and phorbol dibutyrate, which selectively stimulate one or the other of these pathways; their stimulatory effects were compared with those of receptor agonists, such as carbachol and caerulein, which activate phospholipase C. The Ca2+ ionophore ionomycin produced a dose-dependent increase in amylase secretion and intracellular free Ca2+ (as measured by quin-2). The increase in amylase secretion elicited by carbachol or caerulein was accompanied by a small sustained increase in intracellular free Ca2+, following an initial peak. However, the elevation in intracellular free Ca2+ produced by these receptor agonists for a given level of amylase secretion was less than that observed with ionomycin. Phorbol dibutyrate stimulated amylase secretion by a mechanism that was independent of extracellular Ca2+, and no change in intracellular free Ca2+ was observed. Synergistic stimulatory effects of phorbol dibutyrate and ionomycin were observed, whether the phorbol ester was present before, or in combination with, ionomycin. Diacylglycerols containing unsaturated fatty acids (1,2-dioleoylglycerol and 1,3-dioleoylglycerol) also stimulated amylase secretion and exhibited synergistic effects on secretion with ionomycin. These findings suggest that complete activation of amylase secretion from the pancreas requires stimulation of both Ca2+-dependent and protein kinase C-activated pathways.
TL;DR: In this paper, the kinetic equations of alpha-amylase and glucoamylases on starch hydrolysis were modeled by the kinetic equation presented in this paper.
Abstract: Synergistic action of alpha-amylase and glucoamylase on hydrolysis of starch is modeled by the kinetic equations presented in this paper. At the early stage of the reaction alpha-amylase acts as a contributor of newly formed nonreducing ends of starch molecules to glucoamylase by splitting the original starch molecules. This is expressed by the simultaneous differential equations which consist of each rate equation for alpha-amylase and glucoamylase. After the molecular weight of the substrate decreases to the value of about 5000, which is obtained experimentally in this work, the action of alpha-amylase can be neglected and the rate of formation of glucose obeys only the rate equation for glucoamylase.
TL;DR: It is demonstrated by immunohistochemical techniques that calcitonin gene-related peptide (CGRP) is present in nerve terminals in the islets of Langerhans and that interaction of CGRP with this receptor leads to digestive enzyme secretion through a cAMP-mediated pathway.
Abstract: In the present study we demonstrate by immunohistochemical techniques that calcitonin gene-related peptide (CGRP) is present in nerve terminals in the islets of Langerhans. Furthermore, binding studies with 125I-CGRP indicate that dispersed acini from guinea pig pancreas contain a single class of high-affinity binding sites for CGRP with an apparent dissociation constant of 18 nM. Vasoactive intestinal peptide (VIP), rat growth hormone-releasing factor (rGRF), cholecystokinin octapeptide (CCK-OP), and bombesin do not interact with these receptors. Interaction of CGRP with these receptors leads to release of amylase from the acinar cells. Amylase release is half maximal at 0.3 nM CGRP and maximal at 3 nM CGRP. Maximal amylase release with CGRP is one-third of that observed with VIP. CGRP-induced amylase release is dependent on theophylline in the incubation medium. CGRP potentiates the amylase release stimulated by bombesin and CCK-OP but has no effect on amylase release stimulated by VIP, rGRF, and natural glucagon. CGRP stimulates a 25% increase in basal cellular cAMP. These results indicate that guinea pig pancreatic acinar cells contain a novel receptor for CGRP and that interaction of CGRP with this receptor leads to digestive enzyme secretion through a cAMP-mediated pathway. The presence of CGRP in the islets of Langerhans suggests a pathway for CGRP to reach the exocrine pancreas through an insuloacinar portal system.
TL;DR: The most important secretable enzymes found in the salivary glands of Lygus rugulipennis Poppius were polygalacturonase, amylase and alkaline proteinase, which are a basic protein and hydrolyses casein and gelatin with maximal activity at pH 8.0.
TL;DR: An amylase which produces maltotriose from starch as the main product was found in the culture filtrate of a strain of Bacillus subtilis newly isolated from soil.
Abstract: An amylase which produces maltotriose from starch as the main product was found in the culture filtrate of a strain of Bacillus subtilis newly isolated from soil. The enzyme was purified to almost complete homogeneity, as judged by disc electrophoresis in polyacrylamide gel, by means of ammonium sulfate fractionation, DEAE-Sepharose column chromatography and Sephadex gel filtration.The optimum pH and temperature of the enzyme were around 6~7 and 50°C, respectively. Metal ions such as Hg2+, Cu2+, Zn2+, Ni2+ and Fe2+ strongly inhibitied the enzyme activity. The molecular weight was found to be about 25,000 by gel filtration. The yields of maltotriose from short-chain amylose (DP 17), amylopectin, soluble starch and glycogen were about 69, 56, 56 and 40%, respectively.
TL;DR: It is concluded that amylase synthesis in C. thermohydrosulfuricum was inducible and subject to catabolite repression.
Abstract: We studied the general mechanism for regulation of glucoamylase and pullulanase synthesis in Clostridium thermohydrosulfuricum. These amylases were expressed only when the organism was grown on maltose or other carbohydrates containing maltose units. Amylase synthesis was more severely repressed by glucose than by xylose. Catabolite repression-resistant mutants were isolated by using nitrosoguanidine treatment, enrichment on 2-deoxyglucose, and selection of colonies with large clear zones on iodine-stained glucose-starch agar plates. Amylases were produced in both wild-type and mutant strains when starch was added to cells growing on xylose but not when starch was added to cells growing on glucose. In both wild-type and mutant strains, glucoamylase and pullulanase were produced at high levels in starch-limited chemostats but not in glucose- or xylose-limited chemostats. Therefore, we concluded that amylase synthesis in C. thermohydrosulfuricum was inducible and subject to catabolite repression. The mutants produced about twofold more glucoamylase and pullulanase, and they were catabolite repression resistant for production of glucose isomerase, lactase, and isomaltase. The mutants displayed improved starch metabolism features in terms of enhanced rates of growth, ethanol production, and starch consumption.
TL;DR: The majority of enzyme released from the gland accumulated within the peritoneal ascitic fluid, but this intraperitoneal accumulation did not appear to have a significant influence upon lymph or plasma concentrations of amylase or lipase.
Abstract: Acute pancreatitis was induced in anaesthetised dogs in order to investigate the relative contribution of peritoneal ascitic fluid and thoracic duct lymph as routes of transfer of pancreatic enzymes from the inflamed gland to the blood. In eight animals the exudate from the gland was collected in a plastic bag and continuously drained away, and in a further eight it was allowed to accumulate within the peritoneal cavity. The thoracic duct was cannulated and in four of the animals of each group the lymph which drained was discarded; in the other four it was returned via a venous cannula. The initial rise of plasma amylase and lipase was probably because of the direct transfer of enzyme into veins draining the pancreas or peri-pancreatic tissues. Thereafter transfer of enzyme via the thoracic duct significantly influenced plasma concentrations of amylase and lipase. The majority of enzyme released from the gland accumulated within the peritoneal ascitic fluid, but this intraperitoneal accumulation did not appear to have a significant influence upon lymph or plasma concentrations of amylase or lipase.
TL;DR: This article measured the dietary fibre content in white wheat bread, measured with an enzymatic, gravimetric method, was almost 20% higher than in the corresponding flour, which was largely explained by the formation of resistant starch, i.e. starch available to amyloglucosidase only after solubilization with 2m-KOH.
Abstract: The dietary fibre content in white wheat bread, measured with an enzymatic, gravimetric method, was almost 20% higher than in the corresponding flour. The increment was largely explained by the formation of resistant starch, i.e. starch available to amyloglucosidase only after solubilization with 2m-KOH. The resistant starch was formed in the oven or upon cooling of the finished bread. The water content in the dough seemed to influence the extent of the resistant starch formation, whereas changes in the fat content had no effect. The results indicate that the resistant starch might be hard retrograded starch, possibly amylose.
TL;DR: Two procedures are described for determination of isoamylases in human serum with a monoclonal antibody: an enzyme immunoassay for determining amylase of salivary origin, and a routine method in which this amylases is immunoprecipitated and the remaining (pancreatic) amyl enzyme activity is assayed.
Abstract: A monoclonal antibody (66C7) was prepared that specifically binds human salivary amylase (EC 3.2.1.1); it cross reacts with human pancreatic amylase by less than 1%. Two procedures are described for determination of isoamylases in human serum with this antibody: an enzyme immunoassay for determining amylase of salivary origin, and a routine method in which this amylase is immunoprecipitated and the remaining (pancreatic) amylase activity is assayed. Results by the two methods correlate well.
TL;DR: Based on fresh weights of adults feeding on whole wheat through 10 weeks of age, S. oryzae contained three-fold and eight-fold more amylase than S. granarius and S. zeamais Motschulsky, respectively, which may provide this species with an adaptive advantage when feeding on cereals containing naturally occurring amyl enzyme inhibitors.
Abstract: Amylases from adults of Sitophilus oryzae (L.) and S. granarius (L.) were purified by using a sequential procedure of ammonium sulfate precipitation, glycogen-complex formation, and ion exchange chromatography. Amylase of S. oryaze was purified 47.4-fold to a specific activity of 478 units/mg protein. One amylase unit equals 1 mg maltose hydrate produced/min at 30°C. Amylase of S. granarius was purified 85.4-fold to a specific activity of 453 units/mg protein. Amylase of S. oryzae had a Km of 0.173% for soluble starch and consisted of two anionic isozyrnes with isoelectric points of pH 3.70 and pH 3.76. Amylase of S. granarius had a Km of 0.078% for starch and was a single protein with an isoelectric point of pH 3.76. Purified amylases of both species had molecular weights of 56,000 estimated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis, were activated by chloride, and had double energies of activation calculated from Arrhenius plots. Based on fresh weights of adults feeding on whole wheat through 10 weeks of age, S. oryzae contained three-fold and eight-fold more amylase than S. granarius and S. zeamais Motschulsky, respectively. High amylase levels in S. oryzae may provide this species with an adaptive advantage when feeding on cereals containing naturally occurring amylase inhibitors.
TL;DR: The in vivo results showed an overall qualitative similarity to the in vitro results but presented a quantitative difference in the magnitude of the responses for various starch preparations, indicating that the action of pancreatic amylases is an important determinant in the digestion and absorption of these carbohydrates.
Abstract: The effects of cooking and chemical modification of purified starches on the relative rates and extent of their hydrolysis were studied in vitro by using purified human and rabbit pancreatic amylases. Comparison was made with an in vivo study of postprandial glucose and insulin response in adult rabbits. Uncooked starches showed negligible hydrolysis in vitro, whereas cooking (10 min, 100 degrees C) increased both the rate and extent of hydrolysis of all starches. Soluble potato starch was the most and potato amylose the least hydrolyzed. Unmodified tapioca and waxy corn starch were hydrolyzed at the same rate and to the same extent as soluble potato starches. In most cases chemical modification did not change the rate and extent of hydrolysis of the starches. Minor differences between human and rabbit pancreatic amylase exist, but there is a general resemblance between the two amylases in their starch-hydrolyzing properties (correlation coefficient = 0.90; P less than 0.001). The in vivo study showed that uncooked starches elicited no detectable glucose and insulin responses, whereas all the cooked starches except amylose caused glucose and insulin responses comparable to the response seen when feeding glucose. Chemically modified starches (especially waxy corn acetylated distarch adipate) seemed to promote a faster rate of absorption, but the total glucose response (i.e., for the entire 180-min duration) was similar for modified starches and their unmodified counter-parts. The in vivo results showed an overall qualitative similarity to the in vitro results but presented a quantitative difference in the magnitude of the responses for various starch preparations. A good correlation exists between the in vitro and in vivo results (correlation coefficient = 0.84; P less than 0.01). This indicates that the action of pancreatic amylases is an important determinant in the digestion and absorption of these carbohydrates.
TL;DR: Starch fermentation parameters were compared in mono- and cocultures of these two thermoanaerobes to show that the fermentation was dramatically improved as a consequence of coordinate action of amylolytic enzymes and synergistic metabolic interactions between the two species.
Abstract: Clostridium thermohydrosulfuricum and Clostridium thermosulfurogenes produced ethanol and amylases with different components as primary metabolites of starch fermentation. Starch fermentation parameters were compared in mono- and cocultures of these two thermoanaerobes to show that the fermentation was dramatically improved as a consequence of coordinate action of amylolytic enzymes and synergistic metabolic interactions between the two species. Under given monoculture fermentation conditions, neither species completely degraded starch during the time course of the study, whereas in coculture, starch was completely degraded. In monoculture starch fermentation, C. thermohydrosulfuricum produced lower levels of pullulanase and glucoamylase, whereas C. thermosulfurogenes produced lower levels of β-amylase and glucoamylase. In coculture fermentation, improvement of starch metabolism by each species was noted in terms of increased amounts and rates of increased starch consumption, amylase production, and ethanol formation. The single-step coculture fermentation completely degraded 2.5% starch in 30 h at 60°C and produced 9 U of β-amylase per ml, 1.3 U of pullulanase per ml, 0.3 U of glucoamylase per ml, and >120 mM ethanol with a yield of 1.7 mol/mol of glucose in starch. The potential industrial applications of the coculture fermentation and the physiological basis for the interspecies metabolic interactions are discussed.
TL;DR: Although intravenous infusion of digestive end products had only minor effects on the overall amount of pancreatic secretion, circulating end products of digestion can alter the proportion of various digestive enzymes in a selective and short-term manner.
Abstract: The effects of intravenous infusion of amino acids, fat, or glucose on unstimulated pancreatic secretion were studied in 31 healthy male volunteers. Each subject was studied twice on two separate days. On both days pancreatic outputs were measured during a 4-hr basal period that was followed by a 4-hr test period. During the test period either one of the digestive end products (100 ml/hr 10% amino acids in 13 subjects; 100 ml/hr 10% fat in 8 subjects; 150 ml/hr 10% glucose in 10 subjects) or saline was intravenously infused. The infusion of the digestive end products or saline on the two separate days was done in a randomized order. Six of the 10 subjects that had already been studied for glucose received a higher glucose dose (100 ml 20% glucose as a bolus followed by 300 ml/hr 10% glucose) in a third additional experiment. Intravenous infusion of amino acids significantly stimulated pancreatic outputs of trypsin and chymotrypsin, but left the outputs of amylase, lipase, bicarbonate, and volume unaffected. The low-glucose dose, as well as the fat infusion did not alter any of the pancreatic outputs. To analyze the relationships between different enzymes during the infusion of digestive end products, regression lines were calculated from the scatter of all individual pairs of enzyme measurements. Significantly different regression functions were found for each condition (NaCl control, amino acids, fat, glucose) when trypsin and chymotrypsin were plotted versus lipase and amylase: amino acids shifted the function to a trypsin- and chymotrypsin-dominant pattern of secretion, glucose to an amylase-dominant pattern, and fat to a lipasedominant pattern. These results demonstrate that although intravenous infusion of digestive end products had only minor effects on the overall amount of pancreatic secretion, circulating end products of digestion can alter the proportion of various digestive enzymes in a selective and short-term manner.
TL;DR: In this article, an extracellular α-amylase and α-glucosidase were produced by Lipomyces starkeyi CBS 1809 in a medium containing maize starch and soya bean meal.
Abstract: Thermostable, extracellular α-amylase and α-glucosidase were produced byLipomyces starkeyi CBS 1809 in a medium containing maize starch and soya bean meal. Contrary to published findings which suggested a single cell-bound amylolytic system for another strain ofL. starkeyi, this study revealed the presence of two enzymes — an α-amylase and an α-glucosidase inL. starkeyi CBS 1809. The enzymes were separated by solvent and salt precipitation and ion-exchange chromatography on DEAE-Biogel-A. The α-amylase and α-glucosidase had pH optima at 4.0 and 4.5 and temperature optima at 70°C and 60°C, respectively. While the low pH optima are not unique the enzymes are very distinctive in yeasts in having very high temperature optima. The α-glucosidase had highest activities on maltose and isomaltose (100) with relative rates of activity on maltotriose, isomaltotriose and p-nitrophenyl-α-d-glucoside of 59, 48 and 22, respectively. It was inactive towards sucrose. Both the α-amylase and α-glucosidase ofL. starkeyi were located extracellularly and had molecular weights of 76,000 and 35,000, respectively.
TL;DR: Rat pancreatic acinar cells maintained the morphological and ultrastructural characteristics of freshly isolated cells and secreted amylase in response to the secretagogue, carbamyl choline, and can be used to study the regulation of the synthesis of amyl enzyme and other pancreatic enzymes in vitro.
Abstract: Rat pancreatic acinar cells were isolated and cultured in Ham's F12 medium with 15% bovine calf serum. Caerulein, insulin, somatostatin, and dexamethasone (DEX) had no effect on intracellular or secreted amylase in these cultured cells. A serum-free medium, using Waymouth's MB 752/1 supplemented with albumin, epidermal growth factor (EGF), DEX, and HEPES, was then developed to avoid serum factors that might mask hormonal effects. In this SF medium, pancreatic acinar, cells maintained the morphological and ultrastructural characteristics of freshly isolated cells and secreted amylase in response to the secretagogue, carbamyl choline. Insulin, at a concentration of 1 μg/ml, significantly increased intracellular and secreted amylase activity after 3 d. This model cell system can be used to study the regulation of the synthesis of amylase and other pancreatic enzymes in vitro.
TL;DR: The activity of trout and carp amylase is strongly inhibited by wheat flour, an important component of compound fish diets, andAmylase inhibitors of wheat may reduce the digestibility of starch in fish, particularly in carp.
TL;DR: The results indicate that lipase as well as amylase are removed from the serum mainly by glomerular filtration at nearly the same rate, and it is suggested that the differences in the renal handling of both enzymes are due to their differing affinities for hydrophilic and hydrophobic surfaces.
Abstract: Two clinical observations indicate that the kidney plays the main role in the elimination of lipase and amylase from the circulation: 1. in patients with uncomplicated acute pancreatitis the decrease of the activity of both enzymes in the serum ran almost in parallel. The half life for lipase was found to be 6.9-13.7 h, and somewhat higher figures (9.3-17.7 h) were calculated for amylase; 2. in patients with reduced glomerular filtration rate the serum activity of either or of both enzymes was distinctly elevated. The contribution of the kidney to the elimination of lipase and amylase from blood was studied in the rat. After an intravenous bolus injection of homologous lipase and amylase, the serum activity of both enzymes decreased rapidly. The half-life of lipase was 18.1 min, that of amylase 20.5 min. Up to 30% of the injected amylase but only traces of lipase activity were recovered in the urine. In animals with ligated kidneys the serum half-life of both enzymes was 3 times longer. Our results indicate that lipase as well as amylase are removed from the serum mainly by glomerular filtration at nearly the same rate. Reabsorption of lipase is almost complete, in contrast to that of amylase. It is suggested that the differences in the renal handling of both enzymes are due to their differing affinities for hydrophilic and hydrophobic surfaces.
TL;DR: In this paper, an alpha-amylase was obtained from the extracellular culture medium of Aspergillus awamori by means of ethanol precipitation and was found to be stable between pH 3.5 and 6.5.
Abstract: Alpha-amylase was purified from the extracellular culture medium of Aspergillus awamori by means of ethanol precipitation. Sephacryl-200 gel filtration and anion-exchange chromatography on Dowex (AG1-X4) resin. The enzyme preparation was found to be homogeneous by means of sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The purified enzyme had a molecular weight of 54 000 ± 2 500 and its isoelectric point was pH 4.2. The enzyme was found to be most active between pH 4.8 and 5.0 and was stable between pH 3.5 and 6.5. The optimal temperature for the enzyme activity was around 50 °C and the enzyme was stable for at least 1 h up to 45 °C retaining more than 80% of its original activity. The Km (37 °C, pH 5.3) for starch hydrolysis was 1.0 g∙L−1 and maltose inhibited the enzyme activity uncompetitively with a K1 value of 20.05 g∙L−1