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PubMed1986

Secretion of alpha-amylase and multiple forms of glucoamylase by the yeast Trichosporon pullulans.

Trichosporon pullulans IGC 3488 produced extracellular alpha-amylase and glucoamylase activities when grown in batches in a medium containing corn steep liquor and soluble starch or corn starch. alpha-Amylase, unlike glucoamylase activity, was secreted biphasically. For both amylases the maximum concentration was found in stationary phase cultures. The amylolytic enzymes, previously concentrated by ammonium sulfate precipitation, were separated into a glucoamylase fraction and an alpha-amylase fraction by Ultrogel AcA 54 gel filtration. Pullulanase activity was located in the glucoamylase fraction, whereas cyclodextrinase activity was restricted to the alpha-amylase fraction. Isoamylase and alpha-glucosidase were not detected. Electrophoretic analysis showed that alpha-amylase activity was due to a single protein. Glucoamylase, however, occurred in multiple forms. The four glucoamylases and the alpha-amylase were glycoproteins.

Chromatography, Gel↗
PubMed1996

Characterization and distribution of amylases during vegetative cell growth and sporulation of Clostridium perfringens.

Clostridium perfringens produced eight extracellular and two intracellular amylolytic activities when examined by zymograms following polyacrylamide gel electrophoresis under native conditions. The major intracellular amylase was isolated from vegetative cells of C. perfringens. It possessed an estimated molecular mass of 112 kDa. Sulfhydryl and phenol functional groups were essential to its activity. The amylase was endo-acting on starch and also hydrolyzed pullulan. Polyclonal antisera against a purified extracellular amylase did not cross-react with intracellular amylase and the two amylases were biochemically different. The distribution of extracellular amylolytic activities of sporulating cells was different from that of vegetative cells, whereas the distribution of intracellular amylolytic activities remained identical. A significant increase of a particular amylase (A8) occurred in the extracellular fluid during sporulation compared with that during vegetative growth. Regulation of the excretion of amylase(s) may be sporulation and enterotoxingenicity related.

Amylases↗
PubMed1978

Kinetics of amylase release by dispersed acini prepared from guinea pig pancreas.

When incubated with a secretagogue such as cholecystokinin (CCK), dispersed acini prepared from guinea pig pancreas released substantially more amylase than did dispersed single acinar cells. With CCK the rate of amylase release from dispersed acini decreased after 5 min of incubation and remained constant for the subsequent 25 min. The magnitude of the reduction in the rate of amylase release after 5 min was greater with higher concentrations of CCK. With vasoactive intestinal peptide (VIP), the rate of amylase release remained constant for at least 30 min. With CCK plus VIP, potentiation of the rate of amylase release occurred only during the first 15 min of incubation. After 15 min of incubation, the effects of the two peptides were additive. When dispersed acini were first incubated with CCK, potentiation of amylase release occurred only when VIP was added during the initial 10 min of incubation. In contrast, when cells were first incubated with VIP, potentiation of amylase release occurred when CCK was added as long as 30 min after VIP.

Amylases↗
PubMed2002

Stimulatory effects of bilirubin on amylase release from isolated rat pancreatic acini.

Considered to be an etiologic factor of acute pancreatitis, hypersecretion of pancreatic juice and digestive enzymes is often associated with hyperbilirubinemia. We explored the intracellular mechanisms through which bilirubin affects pancreatic exocrine secretory function by examining the effect of bilirubin on isolated rat pancreatic acini. Bilirubin stimulated amylase release in a concentration- and time-dependent manner, significantly increasing amylase release at concentrations >5 mg/100 ml and after 15 min of incubation. Coincubation of bilirubin with vasoactive intestinal polypeptide, 8-bromo-cAMP, or A-23187 had a synergistic effect on amylase release, whereas coincubation with CCK-8, carbamylcholine, or 12-O-tetradecanoylphorbol 13-acetate had an additive effect. Bilirubin did not affect acinar cAMP content or Ca(2+) efflux. Intracellular Ca(2+) pool depletion had no influence on bilirubin-evoked amylase release. The protein kinase C (PKC) inhibitors staurosporine and calphostin C partially but significantly inhibited bilirubin-stimulated amylase release, whereas the PKA inhibitor H-89 did not. The tyrosine kinase (TK) inhibitor genistein, phospholipase A(2) (PLA(2)) inhibitor indoxam, and PLC inhibitor U-73122 also inhibited amylase release. Bilirubin significantly translocated PKC activity from the cytosol to the membrane fraction and activated TK in cytosol and membrane fractions. These results indicate that bilirubin stimulates amylase release by activating PKC and TK in rat pancreatic acini and that PLC and PLA(2) partly mediate this process.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1994

Activin A: negative regulator of amylase secretion and cell proliferation in rat pancreatic acinar AR42J cells.

Activin A, a member of the transforming growth factor-beta supergene family, exists in secretory granules of non-B-cells of rat pancreatic islet (H. Yasuda, K. Inoue, H. Shibata, T. Takeuchi, Y. Eto, Y. Hasegawa, N. Sekine, Y. Totsuka, T. Mine, E. Ogata, and I. Kojima. Endocrinology 133: 624-630, 1993). Because functions of exocrine pancreas are influenced by hormones in pancreatic islet, it is possible that activin A affects the function of pancreatic acinar cells. To examine this possibility, we studied the effects of activin A on amylase secretion and DNA synthesis in AR42J cells. In these cells, dexamethasone (Dx) induces increases in secretory organelles and secretion of amylase (C. D. Logsdon, J. Moessner, J. A. Williams, and I. D. Goldfine. J. Cell Biol. 100: 1200-1208 1985). Activin A did not change the rate of amylase release by itself nor affect the cholecystokinin-stimulated amylase release from Dx-treated differentiated AR42J cells. However, when activin A was added together with Dx, activin A inhibited Dx-induced increase in amylase content in a dose-dependent manner. In the presence of 1 nM activin A, the effect of Dx was abolished. In the absence of Dx, amylase content of the cells was also reduced by activin A in a dose-dependent manner. The maximum inhibitory effect was obtained by 10 nM activin A, and at this concentration amylase content became undetectable. In addition, activin A potently inhibited DNA synthesis as assessed by [3H]thymidine incorporation.(ABSTRACT TRUNCATED AT 250 WORDS)

Activins↗
PubMed2000

Effects of M1 and CCK antagonists on latency of pancreatic amylase response to intestinal stimulants.

In six conscious dogs with gastric and duodenal cannulas, secretin (164 pmol. kg(-1). h(-1) iv) was given to provide a flow of pancreatic juice of approximately 1 drop/s. Amylase activity was measured in each drop before and after rapid intravenous injection of caerulein (7.4 pmol/kg) or intraduodenal injection of L-tryptophan (1 mmol), sodium oleate (3 mmol), and HCl (3 mmol). All experiments were repeated in the presence of the M1 receptor antagonist telenzepine (81 nmol. kg(-1). h(-) iv) and the cholecystokinin (CCK) receptor antagonist L-364718 (0.1 mg/kg iv). Latency of amylase response (time between injection of stimulant and sustained increase in amylase activity greater than mean + 3 SD of prestimulatory activity) to tryptophan (17 +/- 7 s; n = 6) and oleate (16 +/- 5 s) was significantly (P < 0.05) shorter than to caerulein (28 +/- 4 s) and HCl (120 +/- 47 s). Telenzepine significantly increased the latency of amylase response to tryptophan and oleate by >10-fold but not the latency to caerulein or HCl. L-364718 abolished the amylase response to all stimulants. These findings indicate that the early amylase response to intraduodenal tryptophan and oleate is mediated by a neural enteropancreatic reflex ending on M1 receptors rather than by hormone release. However, the activation of (possibly vagal) CCK receptors is essential to run the reflex. The early amylase response to intraduodenal HCl is probably mediated by the release of CCK into the blood circulation.

Amylases↗
PubMed1988

Changes in muscarinic receptors and amylase secretion in regenerating acinar cells of rat pancreas.

Atrophic pancreatic acinar cells of copper-deficient rats recovered after copper supplementation. To clarify whether the recovered cells are regenerative and amylase secretion via muscarinic receptors alters, [3H]-thymidine uptake, [3H]-quinuclidinyl benzilate binding and amylase release were studied in these rats and compared with the values of 5-day-old and 21-week-old rats. The [3H]-thymidine uptake study indicated that the recovered acinar cells were regenerative. The number of muscarinic receptors in regenerating cells was equal to that in mature cells and was one third in cells of 5-day-old rats. The apparent dissociation constant of muscarinic receptors was about 0.73 x 10(-10) M for the regenerating cells, 0.65 x 10(-10) M for 5-day-old rats, and 1.70 x 10(-10) M for 21-week-old rats. Amylase release, as a percent of total amylase, was maintained relatively steady in spite of the low amylase content in regenerating cells. These observations suggest that the affinity of muscarinic receptors increases to compensate the impaired amylase synthesis in regenerating acinar cells and that their amylase secretion via muscarinic receptors is different from that in 5-day-old or mature rats.

Amylases↗
PubMed1993

The effect of somatostatin analogue octreotide on amylase secretion from mouse pancreatic acini.

To clarify whether somatostatin has an inhibitory effect on pancreatic acinar cells, we studied the effect of a long-acting analogue of somatostatin, octreotide, on amylase secretion from isolated mouse pancreatic acini. Octreotide (100 nM) had no inhibitory effects on amylase secretion stimulated by secretin or vasoactive intestinal polypeptide (VIP), while reducing the increase of cyclic adenosine 3',5'-monophosphate (cAMP). On the other hand, octreotide inhibited synergistic amylase secretion induced by secretin or VIP in combination with cholecystokinin (CCK). Octreotide also reduced synergistic amylase secretion by secretin or VIP in combination with calcium ionophore A23187. CCK and A23187 did not alter the increase of cAMP induced by secretin and the inhibitory effect of octreotide on cAMP production. Octreotide did not significantly inhibit amylase secretion stimulated by dibutyryl cAMP (dbcAMP) alone, but reduced synergistic amylase secretion by dbcAMP+A23187. Results obtained above reveal that octreotide has a direct inhibitory effect on amylase secretion from mouse pancreatic acini and probably affects stimulus secretion coupling at a point distal to the production of cAMP, besides inhibiting adenylate cyclase.

Amylases↗
PubMed1979

Relationship between amylase concentration, L/S ratio and lecithin concentrations in amniotic fluid.

Amylase concentration, L/S ratio and lecithin concentration were measured in 110 samples of amniotic fluid in 106 uneventful pregnancies. Amylase concentrations lower than 200 U/l corresponded significantly (p less than 0.001) to a gestational age less than the 37th week as well as to a L/S ratio lower than 2 and to lecithin concentrations lower than 3.5 mg%. Furthermore, amylase values higher than 300 U/l corresponded significantly (p less than 0.001) to a gestational age over the 37th week as to an L/S ratio over 2 and to lecithin concentrations over 3.5 mg%. On the other hand amylase concentrations ranging between 200 and 300 U/l failed to show any significant relationship neither to the age of gestation nor to the concentration of phospholipids. These findings show that the amylase test is a useful method for prediction of fetal maturity. Since the procedure of determination of the amylase concentration is very simple, cheap and rapid, the test can be used as screening method. However, when amylase concentrations are found to range between 200 and 300 U/l specific tests for assessment of fetal maturity have to be applied.

Amniotic Fluid↗
PubMed1989

Role of parotid amylase in starch digestion in the gastro-intestinal tracts of diabetic rats.

In order for the role of parotid amylase in starch digestion in the gastro-intestinal tracts of diabetic rats to be clarified, this study investigated the effect of parotid-duct ligation on both amylase secretion from the parotid glands and pancreas into the gastro-intestinal tract and on starch digestion in the gastro-intestinal contents during feedings. In both diabetic rats and control rats, parotid-duct ligation reduced amylase activity in both the parotid glands during fasting and in the gastric contents after feeding. The amylase activity in the intestinal contents after feeding was reduced by parotid-duct ligation in the diabetic rats. Starch digestion in the gastro-intestinal tract after feeding was reduced by parotid-duct ligation in the diabetic rats. The results suggest that most of the amylase activity in the gastric contents and a large part of the amylase activity in the intestinal contents are derived from the parotid glands, and that parotid amylase plays an important role in starch digestion in the gastro-intestinal tracts of diabetic rats.

Amylases↗
PubMed1990

Characterization of the alpha-amylase receptor of Streptococcus gordonii NCTC 7868.

The purpose of the work described here was to investigate the mechanisms involved in the binding of salivary alpha-amylase to Streptococcus gordonii NCTC 7868 (Challis). Of six types of alpha-amylase studied, only mammalian forms of the enzyme were found to bind to S. gordonii cells. Salivary alpha-amylase binding was inhibited by treatment of cells with trypsin and pronase, but not with pepsin or sodium periodate. Presence of starch, dextrin, or maltoheptaose partially inhibited binding of the enzyme to S. gordonii. Both mutanolysin extracts of cells and culture supernatants contained alpha-amylase-binding activity, which was partially purified by Sepharose CL-6B and DEAE-ion-exchange chromatography. Western blotting detected four putative receptor bands--65 kDa, 15 kDa, 12.5 kDa, and one with a very high molecular weight; the lower-molecular-weight components may be products of proteolytic degradation of the high-molecular-weight material, but their true relationship has yet to be determined. Pre-treatment of salivary alpha-amylase with these putative receptors partially inhibited subsequent binding of the enzyme to S. gordonii cells. When bound to cells, only 19% of the salivary alpha-amylase activity was detectable, suggesting that alpha-amylase binds to the receptor at or near the active site of the enzyme.

Chromatography, Affinity↗
PubMed1993

Salivary alpha-amylase: role in dental plaque and caries formation.

Salivary alpha-amylase, one of the most plentiful components in human saliva, has at least three distinct biological functions. The enzymatic activity of alpha-amylase undoubtedly plays a role in carbohydrate digestion. Amylase in solution binds with high affinity to a selected group of oral streptococci, a function that may contribute to bacterial clearance and nutrition. The fact that alpha-amylase is also found in acquired enamel pellicle suggests a role in the adhesion of alpha-amylase-binding bacteria. All of these biological activities seem to depend on an intact enzyme conformation. Binding of alpha-amylase to bacteria and teeth may have important implications for dental plaque and caries formation. alpha-Amylase bound to bacteria in plaque may facilitate dietary starch hydrolysis to provide additional glucose for metabolism by plaque microorganisms in close proximity to the tooth surface. The resulting lactic acid produced may be added to the pool of acid in plaque to contribute to tooth demineralization.

Animals↗
PubMed1993

The remarkable evolutionary history of the human amylase genes.

Analysis of the structures of the human amylase genes has demonstrated that this multigene family contains at least five tandem gene copies, closely related in sequence but with distinct tissue specific expression. The structures of the genes demonstrate that the human salivary amylase gene was derived from a preexisting pancreatic amylase gene. Insertion of a retrovirus upstream of the amylase gene is responsible for the alteration in tissue specificity. A parotid specific enhancer has been identified within the retrovirus by expression studies in transgenic mice. The independent origin of salivary amylase in rodents and primates suggests that there has been strong evolutionary selection for amylase in saliva. The amylase genes demonstrate a novel mechanism for evolution of new patterns of tissue specific gene expression.

Amylases↗
PubMed1987

Pancreatic acinar cell amylase gene expression: selective effects of adrenalectomy and corticosterone replacement.

To examine the role of glucocorticoids in the regulation of the acinar pancreas, adult male rats were adrenalectomized (Adx) and replaced with no corticosterone (B), normal B, or high B. Plasma B concentration, body weight gain, and thymus weight were used as independent measures of treatment efficacy. Compared to controls, Adx animals had a 75 +/- 0.5% (n = 30) reduction in pancreatic amylase content; a 50% decrease occurred within 1 day and the maximal 75% decrease was observed after 5 days. In Adx animals, amylase content was normalized by normal B replacement and was increased to 235 +/- 39% (n = 30) of control by high B replacement. Furthermore, in all Adx rats, pancreatic content of amylase and plasma B concentration was significantly correlated (r = 0.81, n = 30). The effect of adrenalectomy was selective for amylase; contents of ribonuclease, chymotrypsin, and elastase were not altered. However, the effects of high B replacement were not selective, and increased the content of all digestive enzymes. To determine whether the changes in enzyme content were associated with changes in messenger RNA (mRNA), pancreatic RNA was probed with 32P-labeled complementary DNAs for amylase, ribonuclease, and chymotrypsin. After adrenalectomy and B replacement there was a significant correlation only between amylase mRNA (r = 0.87, n = 13) and plasma B concentration. These data indicate that physiological levels of B have a selective effect on pancreatic amylase gene expression. In contrast, high levels of B have the separate, nonselective effect of increasing the content of all digestive enzymes without increasing corresponding mRNA levels.

Adrenalectomy↗
PubMed1999

Inhibition of stimulated amylase secretion by adrenomedullin in rat pancreatic acini.

Adrenomedullin is a novel hypotensive peptide originally isolated from human pheochromocytoma and recently localized to PP cells of the pancreatic islets of Langerhans. Based on the pancreatic islet-acinar axis model, we investigated the effect of adrenomedullin on regulated exocytosis of exocrine pancreas. Using rat [125I]-adrenomedullin, specific binding sites were localized to rat pancreatic acini. We next examined the effect of adrenomedullin on 100 pM cholecystokinin (CCK)-stimulated amylase release from pancreatic acini. Adrenomedullin inhibited amylase secretion in a dose-dependent manner by approximately 50% at maximum, and the IC50 was 1.1 pM. However, adrenomedullin did not affect rat [125I]CCK binding to isolated acini or reduce the intracellular free Ca2+ concentration increased by CCK. Adrenomedullin also inhibited amylase secretion induced by 1 microM calcium ionophore A23187, suggesting that adrenomedullin inhibits stimulated amylase secretion by functioning at a step(s) distal to the ligand-receptor binding system and intracellular calcium mobilizing mechanism. In streptolysin-O permeabilized acini, 10 nM adrenomedullin shifted the calcium dose-response curve to the right, indicating that adrenomedullin inhibits calcium-induced amylase secretion by reducing calcium sensitivity of the pancreatic exocytotic machinery. In addition, pretreatment of pancreatic acini with pertussis toxin abolished the inhibitory effect of adrenomedullin on CCK-stimulated amylase secretion. These results indicate that adrenomedullin inhibits stimulated amylase secretion by reducing the calcium sensitivity of the exocytotic machinery of the pancreatic acini. A pertussis toxin-sensitive GTP-binding protein(s) is also involved in this mechanism.

Adrenomedullin↗
PubMed1984

Wound amylase levels as an early indicator of orocutaneous fistulae.

The formation of an orocutaneous fistula following ablative head and neck surgery is a common complication. Early fistula detection could permit prompt management, hopefully preventing further wound breakdowns. Amylase is quantitatively the most prominent enzyme in saliva. This study prospectively evaluated whether the amylase content of wound drainage could predict the formation of an orocutaneous fistula earlier than clinically evident. Patients undergoing procedures that required postoperative wound drainage represented the study population. Baseline serum and salivary amylase determinations were obtained. The drainage was assayed for amylase content twice daily. Wound amylase values were then correlated with the patient's clinical course. Results showed wound amylase had a downward trend in uncomplicated postoperative courses. An upward trend of wound amylase was correlated with early fistulization. No pattern was identified in patients with delayed fistulae.

Aged↗
PubMed2004

Characterization and performance of immobilized amylase and cellulase.

The performance of cellulase and amylase immobilized on siliceous supports was investigated. Enzyme uptake onto the support depended on the enzyme source and immobilization conditions. For amylase, the uptake ranged between 20 and 60%, and for cellulase, 7-10%. Immobilized amylase performance was assessed by batch kinetics in 100-300 g/L of corn flour at 65 degrees C. Depending on the substrate and enzyme loading, between 40 and 60% starch conversion was obtained. Immobilized amylase was more stable than soluble amylase. Enzyme samples were preincubated in a water bath at various temperatures, then tested for activity. At 105 degrees C, soluble amylase lost approximately 55% of its activity, compared with approximately 30% loss for immobilized amylase. The performance of immobilized cellulase was evaluated from batch kinetics in 10 g/L of substrate (shredded wastepaper) at 55 degrees C. Significant hydrolysis of the wastepaper was also observed, indicating that immobilization does not preclude access to and hydrolysis of insoluble cellulose.

Amylases↗
PubMed2006

Alpha-amylase activity of Rhyzopertha dominica (Coleoptera: Bostrichidae) reared on several wheat varieties and its inhibition with kernel extracts.

Total progeny of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) reared on 10 wheat, Triticum aestivum L., varieties was evaluated. Higher amylase activities were detected in populations with few individuals, whereas the opposite was observed in higher populations. As protein ingested increased, reproductive success increased. However, consumption of wheat protein was inversely correlated with amylase activity levels (r = -0.66). Amylase activity in homogenates of R. dominica populations showed variable inhibition by wheat extracts prepared from wheat varieties on which they were reared. Insect populations with lowest amylase activities were inhibited more by wheat extracts than those with higher amylase activity (r = -0.77). An electrophoretic analysis revealed four phenotypes showing combinations of three isoamylases (Rm 0.70, 0.79, and 0.90) in different populations of R. dominica. Some of the insect progeny that emerged from resistant wheat varieties contained the three isoamylases, whereas progeny that emerged from the most susceptible varieties showed reduced activity of isoamylases 0.70 or 0.90. These results suggest that the alpha-amylase activity levels and the composition of isoamylases in R. dominica populations are modulated by diet and that the alpha-amylase inhibitory activity of the wheat kernels influences these variations.

Animals↗