Showing papers on "Amylase published in 1980"

Starch Biosynthesis and Degradation

Abstract: Publisher Summary This chapter presents the information known about starch biosynthesis and degradation, and the regulatory phenomena associated with it in leaf and in storage tissue. It also presents at least three possible enzymatic routes from glucose-1-P to the biosynthesis of α 1 - 4 glucosidic linkages in plant systems: the phosphorylase route, via UDP-glucose, or via ADP-glucose. Furthermore, many plant cell extracts contain potent amylase activities that can interfere with the starch synthase assay. The products of starch degradation comprise a major portion of the metabolites of germinating seeds or other reserve tissue that it is relatively straightforward to determine the major products of starch degradation in these tissues. However, in photosynthetic tissues, where starch degradation accounts for only part of the sugar, sugar phosphate and organic acid transformations occurring in the dark, it is more difficult to assign the appearance of intermediates to starch breakdown. Additionally, starch degradation in leaves may be regulated by phosphate concentration.

Structure of a family of rat amylase genes

Abstract: The sequences of two cloned rat pancreatic amylase cDNAs comprising 95% of the mRNA sequence are reported. Analysis of cloned rat genomic DNA fragments using cloned cDNA probes indicates that the rat genome contains multiple closely related amylase genes in which the cDNA sequences are distributed within a region 9 kilobases in length and are interrupted by at least seven intervening sequences.

The adaptation of digestive enzymes to the diet : Its physiological significance

Abstract: Digestive enzymes adapt to the diet when substrate intake is altered. An analysis of experimental works shows that this process includes many enzymes. The intestinal step of digestion is the most important in the enzyme breakdown of dietary components. In the first part of this paper, I have pooled the data on the adaptive potency of pancreatic and intestinal enzymes. When protein, carbohydrate and lipid digestions are considered successively, it is clear that the enzymes involved adapt to any change in substrate intake. For instance, when the amount of starch intake increases, the specific activity of pancreatic amylase is stimulated. At the same time, augmenting the disaccharide level leads to an increase in specific disaccharidase activity, and the absorption rate of some simple hydrolytic products, such as fructose, increases. It thus appears that altering the amount of starch intake leads to a parallel change in the activity of all the enzymes involved in the sequential hydrolysis of the dietary carbohydrates. The second part of the paper discusses the physiological significance of this adaptation in terms of utility to the animal. Two situations are considered in which (i) the nutritional requirements are supplied by food or (ii) they are not supplied either because of a dietary or an enzyme deficiency. When the nutritional requirements, particularly that of protein, are met, adaptation is apparently not useful to the animal. Nevertheless, the role of this adaptation on the hydrolysis rate of different substrates can be supposed. When nutritional requirements are not met, some data show that enzyme adaptation may be advantageous to the animal. If dietary restriction is not too severe and thus the biosynthesis of all the enzymes markedly decreases, then digestive secretions would export considerable nitrogenous material into the gastrointestinal lumen; this material could be a substrate compensating for the essential components lacking in the diet. Any enzyme deficiency leading to substrate decrease is similar to a dietary deficiency. Many experimental studies have shown that in pancreatic deficiency the adaptive potency of the organism is responsible for establishing digestive compensation.

New Strains of Bacillus licheniformis and Bacillus coagulans producing Thermostable α-Amylase Active at Alkaline pH

Abstract: Two species of Bacillus producing thermostable α-amylase with activity optima at alkaline pH are reported here. These organisms were isolated from soil and have been designated as Bacillus licheniformis CUMC 305 and B. coagulans CUMC 512. The enzymes released by these two species were partially purified up to about 81- and 72-fold respectively of the initial activity. The enzyme from B. licheniformis showed a wide temperature-range of activity, with optimum at 91°C. At this temperature it remained stable for 1 h. It retained 40–50% activity at 110°C and showed only 60% of its activity at 30°C. The enzyme showed a broad pH range of activity (4–10) retaining substantial activity on the alkaline side. The optimum pH was 9·5. The enzyme of B. coagulans showed activity up to 90°C, with optimum at 85°C and had a wide pH range with optimum at 7·5–8·5. The hydrolysis pattern of the substrate starch by these enzymes indicated that glucose, maltose, maltotriose and maltotetraose are the principal products rather than higher oligosaccharides.

Changes in Small Intestinal Digestive Enzyme Activity and Bile Acids with Dietary Cellulose in Rats

Abstract: BARBARA O. SCHNEEMAN ANDDANIEL GALLAHERDepartment of Nutrition, University of California,Davis, CA 95616ABSTRACT Rats were fed semipurified diets which contained either20% cellulose, Solka Floe, (HF) or no fiber (C) for 10 days. In the intestinal contents, the HF group had lower activity per milligram contents oftrypsin, chymotrypsin, amylase, lipase and total proteolytic activity. Totalactivity of enzymes in the intestinal contents was also lower, except forchymotrypsin and leucine amino peptidase. Bile acid levels per milligramwere lower in the HF group but the total amount was greater. The totalweight of intestinal contents was greater in the HF group and total amountof protein present was elevated. The results indicate that a source of dietaryfiber, cellulose, can affect the availability of enzymes and bile acids in thesmall intestine. J. Nutr. 110: 584-590, 1980.INDEXING KEY WORDSenzymes •bile acidsdietary fiber •digestion •pancreaticDietary fiber has been reported to increase the fecal excretion of fat and protein (1-4 ). Consumption of fiber may alsoalter the digestion and absorption of lipidand carbohydrate in the small intestine(1, 5). In vitro studies have shown thatcertain dietary fiber sources can lower theactivity of pancreatic lipase, trypsin andchymotrypsin (6). The present study wasundertaken to determine whether feedinga purified source of fiber, cellulose, couldaffect the intestinal activity of certain digestive enzymes and the level of bile acidsand cause adaptive changes in the enzymecomposition of the pancreas.

Effects of controlled gas environments in solid-substrate fermentations of rice

Abstract: The gas environment is solid-substrate fermentations of rice significantly affected levels of biomass and enzyme formation by a fungal species screened for high amylase production. Constant oxygen and carbon dioxide partial pressures were maintained at various levels in fermentations by Aspergillus oryzae. Control of the gas phase was maintained by a “static” aeration system admitting oxygen on demand and stripping excess carbon dioxide during fermentation. Constant water vapor pressures were also maintained by means of saturated salt solutions. High Oxygen pressures stimulated amylase productivity significantly. On the other hand, amylase production was severely inhibited at high carbon dioxide pressures. While relatively insensitive to oxygen pressure, maximum biomass productivities were obtained at an intermediate carbon dioxide pressure. High oxygen transfer rates were obtained at elevated oxygen pressures, suggesting, in view of the stimulatory effect of oxygen on amylase production, a stringent oxygen requirement for enzyme synthesis. Solid-substrate fermentations were highly advantageous as compared with submerged cultures in similar gas environments. Not only were amylase productivities significantly higher, but the enzyme was highly concentration in the aqueous phase of the semisolid substrate particles and could be extracted in a small volume of liquid. Results of this work suggest that biomass and product formation in microbial processes may be amenable to control by the gas environment. This is believed to offer an interesting potential for optimizing selected industrial fermentation processes with respect to productivity and energy consumption.

Effects of ethionine on digestive enzyme synthesis and discharge by mouse pancreas

Abstract: The earliest changes noted during the evolution of pancreatitis induced by feeding mice a choline-deficient ethionine-supplemented (CDE) diet are an increase in the number of zymogen granules in pancreatic acinar cells and an increase in digestive enzyme content of the pancreas. We have studied the processes of protein and digestive enzyme synthesis and discharge at varying times after institution of the CDE diet, a choline-deficient diet (CD), and a diet containing ethionine but not choline-deficient (E). Both the CDE and E diets increased digestive enzyme content within 12 h of their institution. Both the CDE and E diets reduced the rate of protein and amylase synthesis and caused a marked reduction in the rate of protein and amylase discharge from the pancreas. These changes were greatest and were noted earliest in the CDE diet group. A marked reduction in secretagogue-induced in vivo and in vitro amylase discharge followed ingestion of either the CDE or E diet. These studies indicate that the increased pancreatic content of digestive enzymes noted after ingestion of the CDE and E diets results from an ethionine-induced decrease in the rat of digestive enzyme discharge. This phenomenon is enhanced by simultaneous choline deficiency. Subsequent intrapancreatic activation of zymogens may couple these changes in enzyme content to the development of hemorrhagic pancreatitis.

Effect of cultivar, size, storage, and cooking method on carbohydrates and some nutrients of sweet potatoes.

Abstract: A study was conducted to determine the effects of cultivar, root size, cooking method and storage on carbohydrates and quality attributes of sweet potatoes. Roots were analyzed after curing and after 7 months storage for sugars, starch, pectins, hemicellulose, cellulose, ascorbic acid, and carotenoids. Sensory evaluations were also conducted. ‘Centennial’ and ‘Jasper’ contained the highest percentages of total sugars, starch, water-soluble pectin, hemicellulose and carotenoids, while ‘Georgia Jet’ was lowest in all carbohydrates except reducing sugars and water-soluble pectin. Baked and microwave cooked roots were highest in most of the carbohydrates; however, canned roots were higher in starch because of the rapid inactivation of amylase during cooking. Boiled roots were lower in carotenoids while canned roots were lowest in ascorbic acid. There was a decrease in reducing sugars, starch, pectins, hemicellulose, and cellulose during 7 months storage. Sensory ratings for color intensity and attractiveness corresponded to carotenoid content, CDM ‘L’ value, and hue angle (orangeness). Roots of different cultivars, size and storage period responded differently to cooking methods, thus producing significant interactions. Baking produced the highest quality cooked product as compared to other cooking methods.

Specific Protein Phosphorylation during Stimulation of Amylase Secretion by β‐Agonists or Dibutyryl Adenosine 3′,5′‐Monophosphate in the Rat Parotid Gland

Abstract: The present study was undertaken in order to examine the possible involvement of protein phosphorylation during beta-adrenergic stimulation in the rat parotid gland. Isolated parotid gland slices were stimulated by either isoproterenol or dibutyryl adenosine 3',5'-monophosphate (Bt2cAMP) in the presence or absence of propranolol. Amylase output was measured as a parameter for the degree of stimulation of secretion. Stimulation of secretion by either isoproterenol or Bt2AMP was associated with phosphorylation of three protein bands as revealed by sodium dodecylsulfate/polyacrylamide gel electrophoresis and autoradiography. The apparent molecular weights of the three proteins were 35,100 (protein I), 25,700 (protein II) and 20,400 (protein III). After cell fractionation by differential and gradient centrifugation, protein I was enriched in a light membrane fraction most likely corresponding to the plasma membrane as revealed by marker enzyme analysis. Proteins II and III were recovered in a denser fraction containing mainly mitochondria and rough microsomes. The effect of isoproterenol but not that of Bt2cAMP on phosphorylation of all three protein bands was completely abolished by propranolol. The different time course in the stimulation of amylase secretion by isoproterenol and Bt2cAMP respectively was reflected by corresponding differences in the time course of protein phosphorylation.

Effects of dietary pectin and fat on the small intestinal contents and exocrine pancreas of rats.

Abstract: The effects of dietary pectin and fat level on digestive enzyme activities in the pancreas and small intestine and on intestinal bile acid levels were investigated. In unfed rats, dietary pectin did not influence the pancreatic enzymes studied, but a higher level of corn oil in the diet lowered the amylase activity in the pancreas, increased pancreatic lipase activity and slightly lowered the chymotrypsin and trypsin activities. Diet did not change the dry weight of the pancreas. In the fed rats, dietary pectin increased the dry weight of the small gut wash plus the mucosal scraping. Dietary pectin increased the small intestinal lipase and chymotrypsin levels and at the low level of fat only, increased amylase and trypsin activities in the small intestine of fed rats. Intestinal lipase levels were higher and amylase levels lower in rats consuming the high level of corn oil. These results indicate that changes in dietary fat level led to changes in the amylase and lipase content of secreted pancreatic juice and that differences in absorption associated with diets containing pectin could be the result of increased material in the small intestine.

Interaction of wheat monomeric and dimeric protein inhibitors with alpha-amylase from yellow mealworm (Tenebrio molitor L. larva).

Abstract: The highly purified alpha-amylase from Tenebrio molitor L. larva (yellow mealworm) reversibly combines with two closely related homogeneous glycoprotein inhibitors, one dimeric (termed ‘inhibitor 0.19’) and one monomeric (termed ‘inhibitor 0.28’), from wheat flour. As established by means of difference spectroscopy and kinetic studies, molar combining ratios for the amylase–inhibitor-0.19 and amylase-inhibitor-0.28 complexes were 1:1 and 1:2 respectively. Two amylase–inhibitor-0.19 complexes with slightly different retention volumes on Bio-Gel P-300 and only one amylase–inhibitor-0.28 complex were observed. Dissociation constants of the amylase–inhibitor-0.19 and amylase–inhibitor-0.28 complexes were 0.85 nM and 0.13 nM respectively. A strong tendency of both complexes to precipitate under an ultracentrifugal field was observed; the minimum molecular weight calculated for the two complexes under such conditions was approx. 95 000. The two complexes showed difference spectra indicating involvement of structurally related or identical tryptophyl side chains in the binding of inhibitors 0.28 and 0.19 to the amylase. A model summarizing the main features of the inhibition of the insect amylase by the two wheat protein inhibitors is proposed.

Proteins synthesized and secreted during rat pancreatic development.

Abstract: The synthesis and secretion of proteins during development of the pancreas was analyzed using two-dimensional gel electrophoresis. The pattern of synthesis of the total proteins of the pancreas was found to change very little from 14 to 18 d gestation. In addition, the protein synthetic pattern of the embryonic pancreas was very similar to the protein patterns of several other embryonic tissues (gut, lung, and mesenchyme). Between 18 d gestation and the adult stage, the synthesis of the majority of protein species fades as the synthesis of the secretory (pro)enzymes becomes dominant. Thus, the terminal differentiation of the pancreas appears to involve the dominant expression of a limited set of genes (coding, in part, for the digestive [pro]enzymes) while the pattern of expression of the remaining domain remains relatively unchanged. Many of the secretory (pro)enzymes were identified and their synthesis during development was monitored. The synthesis of several secretory proteins was detected between 15 and 18 d gestation (e.g., amylase and chymotrypsinogen), whereas the synthesis of others was not detected until after 18 d gestation (i.e., trypsinogen, ribonuclease, proelastase, and lipase). Between 18 d gestation and the adult stage, the synthesis of the digestive (pro)enzymes increases to > 90% of pancreatic protein synthesis. The secretion of digestive (pro)enzymes was detected as early as 15 d gestation. The selective release of a second set of proteins was detected in the early embryo. These proteins are not detected in the adult pancreas or in zymogen granules but are also released by several other embryonic tissues. The function of this set of proteins is unknown.

Starch Degradation in Spinach Leaves: ISOLATION AND CHARACTERIZATION OF THE AMYLASES AND R-ENZYME OF SPINACH LEAVES.

Abstract: The properties of two amylase activities which differ in their substrate specificity and subcellular location as well as a chloroplast-associated R-enzyme (debranching activity) are reported. An extrachloroplastic amylase is resolved by gel filtration chromatography into two activities of 80,000 and 40,000 daltons. Both extrachloroplastic activities hydrolyze amylopectin and shellfish glycogen and only slowly hydrolyze rabbit liver glycogen, β-limit amylopectin, and amylose. In contrast, the major chloroplastic amylase attacks all of these glucans at comparable rates. Glucan hydrolysis by both the extrachloroplastic and chloroplastic amylase generates not only maltose but appreciable amounts of other oligosaccharides, whereas maltotetraose hydrolysis produces glucose, maltose, and maltotriose. The action patterns displayed by the amylase activities indicate that both are endoamylases, although they lack the typical Ca 2+ requirement or heat stability of seed endosperm α-amylases. Dithiothreitol, glutathione (oxidized or reduced), ascorbate, dehydroascorbate, and dithiothreitol plus thioredoxin have no effect on either the chloroplastic or extrachloroplastic amylase activities. The chloroplastic R-enzyme debranches amylopectin, β-limit amylopectin, pullulan, and α-limit dextrins, but not rabbit liver glycogen. An increase in extinction coefficient and λ max is detected when the debranched amylopectin and β-limit amylopectin form a complex with I 2 -KI. Based on these properties, the chloroplastic R-enzyme is similar in enzymic activity to the R-enzyme observed in endosperm tissue.

Dietary fiber, lignocellulose and hemicellulose contents of selected foods determined by modified and unmodified van soest procedures

Abstract: Neutral detergent residues (NDR) of 6 vegetables, 3 fruits, and 3 grain products were determined by the unmodified Van Soest ND procedure and by modifications which incorporated starch-or protein-hydrolyzing enzymes. Modification of the procedure significantly lowered NDR weights of several foods, with the greatest effect on grain products and high starch vegetables. Incubation with B. subtilis amylase and pancreatin (1 hr) yielded NDR which generally were not different from those incubated with hog amylase (18 hr). Modification of the procedure had little effect on lignocellulose values, determined by treating NDR with acid detergent solution, and more effect on hemicellulose values. Results suggest that amylase treatment, but not a long incubation, may be necessary for some foods.

Kinetics of Growth and Amylase Production of Saccharomycopsis fibuligera on Potato Processing Wastewater.

Abstract: The kinetics of growth and amylase production of Saccharomycopsis fibuligera were studied in a chemostat on a synthetic potato processing blancher water. Dilution rates (D) from 0.101 to 0.480 h−1 were examined. A mathematical model based on the Monod equation was developed. The yield of cell mass from carbohydrates was constant and equal to 0.84. The maximum specific growth rate and the Monod constant were determined to be 0.596 h−1 and 0.226 mg/ml, respectively. An equation for the steady-state starch concentrations was empirically derived. The steady-state noncarbohydrate carbon levels rose linearly with D. Reducing sugars were the growth-limiting substrate, and their steady-state levels conformed to Monod kinetics. The yield of amylase from the cell mass (Yz) declined as D rose and was described by the equation Yz = (−8.005D + 4.076). The model predicted that the maximum production of cell mass should occur at D = 0.35 h−1 and the maximum production of amylase should occur at D = 0.22 h−1. The mathematical model presented agreed with the experimental results in its prediction of the steady-state level of reducing sugar, starch, cell mass, and amylase concentrations as well as the productivity of amylase.

Production of amylase(s) by Schwanniomyces castellii and Endomycopsis fibuligera.

Abstract: Schwanniomyces castellii and Endomycopsis fibuligera Produced extracellular amylase(s) when grown on various carbon sources and at different pH values. Both yeast species showed significant amylase synthesis in the presence of either maltose or soluble starch. On the other substrates tested (glucose, cellobiose, sucrose, trehalose, melezitose, raffinose, ethanol, glycerol) differences were found regarding growth and amylase production. Free glucose in the culture medium apparently inhibited enzyme synthesis. The pH range allowing maximal growth and amylase production was 4.5–6.0 for E. fibuligera and 5.5–7.0 for S. castellii.

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds: 9. DE NOVO SYNTHESIS OF beta-AMYLASE.

Abstract: Germinating rice seeds were fed with [(35)S]methionine and the incorporation of (35)S into beta-amylase demonstrated by quantitative immunoprecipitation using rabbit anti-beta-amylase immunoglobulin G fraction. Separation of the antigen-antibody complex by Na-dodecylsulfate gel electrophoresis and subsequent radioautography clearly showed the radioactive labeling of the beta-amylase molecule. The specific radioactivity of beta-amylase derived from scutellum by immunoprecipitation was significantly greater than that of the endosperm. The results strongly indicate that at the onset of germination of rice seeds beta-amylase is synthesized de novo in the scutellum and that in later stages there occurs activation of an inactive, latent form of the enzyme associated with starch granules in the endosperm. In later stages of germination this activated form of the enzyme becomes dominant.

Characterization of an Extracellular β-Amylase from Bacillus megaterium sensu stricto

Abstract: Bacillus megaterium sensu stricto (NCIB 7581) produced amylase throughout exponential growth and during the early-stationary phase. Enzyme synthesis occurred in the absence of α-glucans but the yield was maximal when malt extract or starch was supplied as carbon source. Of the nitrogen sources examined, soya flour stimulated the highest yield of amylase. The enzyme was susceptible to reagents that react with thiol groups and had an exo-action on starch yielding maltose with a β-anomeric configuration. It is concluded that the principal starch-hydrolysing enzyme from B. megaterium NCIB 7581 is a (1-4)-α-D-glucan maltohydrolase similar in its properties to other Bacillus and plant β-amylases.

Inheritance of a Parotid Secretory Protein in Mice and Its Use in Determining Salivary Amylase Quantitative Variants

Abstract: Among inbred strains of mice, a major protein, PSP, produced and secreted by the parotid glands, shows variation in electrophoretic mobility and in the peptides produced by cyanogen bromide treatment. This variation is inherited as a single Mendelian factor with two alleles showing co-dominant expression. In genetic crosses, it segregates independently from the amylase complex and is closely linked to the agouti locus on chromosome 2. The protein ratios between amylase and PSP in saliva, obtained by scanning of electrophoretic gel separations, were found to reflect genetic differences in salivary amylase production in strains YBR/Cv and C3H/As.