Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMYLASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed1989

The calcium requirement for stability and enzymatic activity of two isoforms of barley aleurone alpha-amylase.

alpha-Amylases (EC 3.2.1.1) secreted by the aleurone layer of barley grains are Ca2+-containing metalloenzymes. We studied the effect of Ca2+ on the activity and structure of the two major groups of aleurone alpha-amylase by incubating affinity purified enzyme in solutions containing Ca2+ from pCa 4 to 7. Both groups of isoforms required one atom of Ca2+/molecule of enzyme as determined by isotope exchange, but the two groups differed by more than 10-fold in their affinity for Ca2+. Both groups of alpha-amylase were irreversibly inactivated by incubation in low Ca2+ (pCa 7). This inactivation was not due to changes in primary structure, as measured by molecular weight, but appeared to be the result of changes in secondary and tertiary structure as indicated by circular dichroism spectra, serology, lability in the presence of protease, and fluorescence spectra. Analysis of the predicted secondary structure of barley aleurone alpha-amylase indicates that the Ca2+-binding region of barley amylases is structurally similar to that of mammalian alpha-amylases. Our data indicate that micromolar levels of Ca2+ are required to stabilize the structure of barley alpha-amylases in the endoplasmic reticulum of the aleurone layer where these enzymes are synthesized.

Calcimycin↗
PubMed1987

Translational control of alpha-amylase gene expression in Aspergillus awamori.

Regulation of alpha-amylase gene expression in Aspergillus awamori was studied by analyzing the enzyme activity levels, rate of protein synthesis, and alpha-amylase-specific mRNA levels under various conditions of growth. alpha-Amylase synthesis was sensitive to catabolite repression as glucose repressed its synthesis by about fourfold. The stimulation of alpha-amylase synthesis in the presence of its substrate starch was shown to be due to derepression rather than induction as the enzyme was synthesized at similar rates in both starch and starvation media. Repression and derepression of enzyme synthesis was found to be mediated at the translational level. The cellular levels of alpha-amylase-specific mRNA as measured by an in vitro translation assay system, were almost identical under all conditions of enzyme synthesis. Relative in vivo and in vitro alpha-amylase mRNA template activities suggest that alpha-amylase mRNA is translated much more efficiently during the derepression than under the conditions of repressed synthesis.

Aspergillus↗
PubMed1981

P3 amylase isoenzyme in patients with cholelithiasis.

The plasma P3 amylase isoenzyme was determined in 25 patients with proven cholelithiasis. In six patients who had a single gallstone and normal pancreas at operation, the total plasma amylase was within normal limits and the P3 amylase isoenzyme was absent. In the remaining 19 patients who had multiple gallstones, pancreatitis was found at surgery in 10. In this group of 10 patients, the total plasma amylase was above the reference range for healthy individuals in only five (50%), while the P3 amylase isoenzyme band was detected in all 10 (100%). It is concluded that P3 amylase isoenzyme is superior to the total plasma amylase in the diagnosis of pancreatitis in patients with gallstone.

Amylases↗
PubMed1982

Amylase in fallopian tube and serous ovarian neoplasms: immunohistochemical localization.

We studied the cellular localization of amylase in normal Fallopian tubes and serous ovarian neoplasms using an indirect immunoperoxidase technique. The primary antiserum was against human pancreatic amylase, and was found to inhibit ovarian tumor amylase as well. Amylase was present in normal endosalpingeal epithelium and in the epithelial cells of benign, borderline, and malignant serous ovarian tumors. A mucinous cystadenoma was also studied and contained no amylase. This localization suggests that amylase production by serous ovarian neoplasms reflects the endosalpingeal differentiation of these tumors. Antibody to amylase may be potentially useful in distinguishing serous ovarian tumors from other forms of ovarian neoplasia.

Amylases↗
PubMed1981

Serum amylase and lipase activities in the diagnosis of pancreatitis in dogs.

To determine the usefulness of information provided by measurement of serum amylase activity in the evaluation of dogs for pancreatitis, the relationship of amylase activity to lipase activity in 713 paired serum samples was investigated by statistical analysis. Little change in mean amylase concentration was found until lipase values exceeded 800 U/L. The ranges of amylase activity (mean +/- 2 SD) were essentially the same for dogs with no pancreatitis (0 to 100 U of lipase activity/L) as for dogs with a high probability for the disease (700 to 799 U of lipase activity/L), 0 to 4,029 U/L and 857 to 4,869 U/L, respectively. Pathologic findings from biopsy and necropsy reports from 92 dogs for which serum lipase determinations were done indicated that serum lipase increased not only with pancreatitis, but also with other medical problems, such as renal and hepatic disease. It was concluded that determination of serum amylase activity without knowledge of serum lipase activity was of little value to diagnose pancreatitis. High amylase activity was not specific for pancreatitis and low amylase activity could not rule out the disease. The results of this study also showed that low serum lipase values almost always eliminated the possibility of pancreatitis and that high values were often, but not always, diagnostic for pancreatitis.

Amylases↗
PubMed1983

Effect of cholinergic stimulation on the distribution of amylase activity.

The amylase activity was measured in the several tissues and plasma after pancreatectomy in the rat. Pancreatectomy decreased the alpha-amylase content of the blood and several tissues in the rat, whereas the amylase activity did not change in the submandibular gland. Especially, the content of the small intestine lost about 99% of its amylase activity as did the small intestinal mucosa. After cholinergic stimulation, the amylase activity in several tissues and plasma tended to increase but the increase was not statistically significant. Only the enzyme activity in the lumen of the small intestine and distal intestine increased substantially after cholinergic stimulation. However, the maximal concentration in the small intestine was still only 2% of that in the normal non-pancreatectomized animal. The data suggest that the absence of the dramatic increase in the amylase activity in the plasma and several tissues that was observed in the normal rat after this pattern of cholinergic stimulation was due to the absence of the potential source of amylase, the pancreas.

Animals↗
PubMed1994

[Are amylases in bakery products and flour potential food allergens?].

The enzyme alpha-amylase from the mould Aspergillus oryzae (Asp o II) routinely used for the production of bread, cakes and pastries has in recent years been identified as an inhalative allergen for occupational diseases (bakers' asthma). It is doubtful whether this amylase in the final product, i.e. after the baking procedure, can still be regarded as an allergen. To clarify this question, detailed case histories on 138 subjects were recorded (98 allergics, 20 patients suffering form chronic intestinal diseases, 20 healthy controls). The clinical examinations included prick skin test and IgE antibody determination using one of the customary enzyme preparations. EAST showed a few of these 138 bread consumers to be weakly sensitized to the enzyme. One of the subjects displayed a significant reaction to alpha-amylase heated to 200 degrees C. As expected, eleven bakers sensitized to alpha-amylase by inhaling it in the workplace (positive prick test, positive case history) predominantly exhibited specific IgE antibodies to the native enzyme. Apart from one weakly positive finding, heated alpha-amylase yielded negative results in this collective. Baking conditions vary widely, especially with regard to single components, temperature and duration. Thus, further investigations as to residual allergenicity or the feasible occurrence of new antigenic determinants during the production of bread, cake and pastries are required. 27% of bakers examined and 9% of atopics showed antibodies to a flour inherent enzyme, a beta-amylase. On the whole, the selected conditions hinted at a weakly sensitizing potential inherent in baking flour and in added amylase.

Allergens↗
PubMed1997

Crystal structure of thermostable alpha-amylase from Bacillus licheniformis refined at 1.7 A resolution.

alpha-Amylases (alpha-1,4-glucan-4-glucanohydrolase, E.C.3.2.1.1) catalyze the cleavage of alpha-1, 4-glucosidic linkages of starch components, glycogen, and various oligosaccharides. Thermostable alpha-amylases from Bacillus species are of great industrial importance in the production of corn syrup or dextrose. Thermostable alpha-amylase from Bacillus licheniformis, a monomeric enzyme with molecular mass of 55,200 Da (483 amino acid residues), shows a remarkable heat stability. This enzyme provides an attractive model for investigating the structural basis for thermostability of proteins. The three-dimensional structure of thermostable alpha-amylase from Bacillus licheniformis has been determined by the multiple isomorphous replacement method of X-ray crystallography. The structure has been refined to a crystallographic R-factor of 19.9% for 58,601 independent reflections with F0 > 2 sigma F0 between 8.0 and 1.7 A resolution, with root mean square deviations of 0.013 A from ideal bond lengths and 1.72 degrees from ideal bond angles. The final model consists of 469 amino acid residues and 294 water molecules. Missing from the model are the N- and C-termini and the segment between Trp182 and Asn192. Like other alpha-amylases, the polypeptide chain folds into three distinct domains. The first domain (domain A), consisting of 291 residues (from residue 3 to 103 and 207 to 396), forms a (beta/alpha)8-barrel structure. The second domain (domain B), consisting of residues 104 to 206, is inserted between the third beta-strand and the third alpha-helix of domain A. The third C-terminal domain (domain C), consisting of residues 397 to 482, folds into an eight-stranded antiparallel beta-barrel. Neither calcium ion nor chloride ion is located near the active site. This study reveals the architecture of the thermostable alpha-amylase from Bacillus licheniformis. By homology with other alpha-amylases, important active site residues can be identified as Asp231, Glu261, and Asp328, which are all located at the C-terminal end of the central (beta/alpha)8-barrel. Since many of the stabilizing and destabilizing mutations obtained so far fall in domain B or at its border, this region of the enzyme appears to be important for thermostability. The factors responsible for the remarkable thermostability of this enzyme may be increased ionic interactions, reduced surface area, and increased packing interactions in the interior.

Amino Acid Sequence↗
PubMed1997

In vitro amylase release of preserved pancreas: a simple test to assess the viability of pancreatic allograft during preservation in the pigs.

To determine an in vitro marker of viability during pancreatic preservation, 12 pigs underwent total pancreas harvesting, and graft were stored in Euro-Collins or Belzer perfusion solution for up to 24 hours. Amylase concentration of the storage solution was analyzed in regular periods and tissue samples were taken for acridine-orange histochemical evaluation of viability in the same time. In vitro pancreatic amylase release (IU/g pancreas tissue) was calculated from the volume of solution and the weight of graft. A significant increase of amylase release was found in the course of preservation in both media. Comparing amylase release in different solutions we found significant difference between Euro-Collins and Belzer media (4 hours: 6.45 IU/g vs. 2.2 IU/g, 8 hours: 11.5 vs. 3.58, 24 hours: 8.7 vs. 42.8, respectively). Comparison of amylase release with histochemical evaluation of viability showed strict correlation. We concluded that amylase release is a good marker for exocrine tissue destruction as well as viability of preserved pancreas. Our data confirms that Belzer solution is superior in pancreatic preservation. It is suggested that after adaptation into human model in vitro pancreatic amylase release could be a time- and cost-saving, useful method in predicting pancreatic transplant function prior graft implantation.

Acridine Orange↗
PubMedDate not supplied

[Amylase production by Aureobasidium pullulans in liquid and solid media].

Amylase production by a strain of Aureobasidium pullulans isolated in the laboratory was evaluated in liquid media (complex and synthetic) and in solid medium (wheat bran). There was an inhibitory effect in amylase production or amylase secretion by glucose. Asparagine was the best nitrogen source for amylase production (4-6 g/l). Only chlamidospores and melanin but not, amylase activity, were obtained with ammonium sulfate. Amylase production in solid culture was higher than the production obtained in the liquid media assayed. Optimum initial moisture content in solid culture ranged between 57 and 74%. No difference was observed in amylase production between solid media inoculated with cells grown in liquid or solid media.

Culture Media↗
PubMed1995

[Amylase production of Streptomyces rimosus TM-55 and their 2-deoxyglucose resistant mutants].

Streptomyces rimosus TM-55 was treated with 3% ethyl melthylsulfonate for 60 minutes to generate mutants producing high amount of amylase, and 1,283 mutants were isolated from yeast extract starch (YS) medium containing 0.1% 2-deoxyglucose. Amylase activity was primarily screened by clear zone formation on YS medium after spraying with iodine solution. Two mutants designed as D-35 and D-62 had higher amylase activity than that of the parent strain. Amylase activity of the mutants in the YS broth was 2.97- and 3.45-fold of the parent strain, respectively. With the addition of 0.1% lactose, and 2-deoxyglucose, amylase activity of the mutants D-35 and D-62 was 27-73% and 4-7% higher than that of the parent strain. With the addition of 0.1% sucrose, amylase activity of the mutant D-35 was 18.37% lower than that of the parent strain. Moreover, with the supplement of 0.1% glucose, amylase activity of both the mutants D-35 and D-62 was 3.67 and 3.40 fold of the parent strain.

Amylases↗
PubMed1998

Characteristics of amylase secretion induced by various secretagogues examined in perifused rat parotid acinar cells.

Isolated parotid acinar cells embedded in Bio-Gel P-2 resin were perifused in small columns, and the effects of various agonists and their combinations on amylase release were studied. Isoproterenol gradually increased the rate of amylase secretion; its maximum response was attained about 5 min after the stimulation. A similar time course of changes in amylase secretion was elicited by dibutyryl cyclic AMP, forskolin and isobutylmethylxanthine. Carbachol (CCh) and substance P evoked biphasic stimulation of amylase secretion; an initial rapid and large peak and a following sustained plateau. The magnitude of the maximum response induced by CCh or substance P was almost the same as that induced by isoproterenol. In Ca2+-free medium, CCh evoked only the initial peak and did not produce the sustained plateau, but the effect of isoproterenol was little changed. Amylase secretion induced by isoproterenol, but not by CCh and substance P, was markedly decreased by lowering the temperature of the medium. Combined addition of isoproterenol and 1 microM CCh markedly augmented amylase secretion; the magnitude of its response was about three times that induced by isoproterenol alone. Potentiation was also observed between alpha- and beta-adrenergic receptors. Most of these results were very different from those obtained in batch systems. Thus, use of a perifusion system for analysis of amylase secretion is strongly recommended.

1-Methyl-3-isobutylxanthine↗
PubMed1963

EFFECT OF CARBON SOURCES ON FORMATION OF ALPHA-AMYLASE BY BACILLUS STEAROTHERMOPHILUS.

Welker, N. E. (Western Reserve University, Cleveland, Ohio) and L. Leon Campbell. Effect of carbon sources on formation of alpha-amylase by Bacillus stearothermophilus. J. Bacteriol. 86:681-686. 1963.-A chemically defined medium was devised for use in alpha-amylase induction studies. The addition of 0.1% casein hydrolysate to the chemically defined medium permitted growth on fructose, and with glucose, sucrose, maltose, starch, and glycerol it shortened the lag period and increased both the growth rate and the total enzyme produced. Growth did not occur when gluconate, acetate, or succinate were used as carbon sources. alpha-Amylase was produced during the logarithmic phase of growth; the amount produced was inversely proportional to the rate of growth. The poorer the carbon source for growth (glycerol, k = 0.24; glucose, k = 0.26; sucrose, k = 0.42), the higher was the amount of enzyme produced (glycerol, 109 units/ml; glucose, 103 units/ml; sucrose, 45 units/ml). Cells grown on technical-grade maltose (k = 0.26) or starch (k = 0.42) did not conform to this relationship in that unusually large amounts of alpha-amylase were produced (362 and 225 units/ml, respectively). Cells grown on fructose or sucrose had the same growth rate (k = 0.42), but smaller amounts of alpha-amylase were produced on fructose (fructose, 0 to 4 units/ml; sucrose, 45 units/ml). An intracellular alpha-amylase was not detected in Bacillus stearothermophilus.

Amylases↗
PubMed1989

Evaluation of serum iso-amylase in the normal dog using an improved electrophoretic technique.

Six iso-amylase fractions are known to exist in human serum, three originating from the salivary glands and three from the pancreas. Although it is known that a different number and source of iso-amylase fractions occur in the dog, the routine detection of all the canine iso-amylase fractions has not been previously established. Earlier methods detected either two iso-amylase fractions or, in a proportion of cases, four fractions. A method is described which detects four iso-amylase fractions in 95% of normal canine serum samples. Trials have shown the method is reproducible and that freezing at -40 degrees C has no effect on iso-amylase activity. The normal values for iso-amylase are recorded in 18 normal dogs.

Analysis of Variance↗
PubMed1996

Biological and chemical evaluation of chick pea seed proteins as affected by germination, extraction and alpha-amylase treatment.

The effects of germination, extraction (double extraction with 70% ethanol and water at isoelectric point) and alpha-amylase treatments of chick pea seed flours on crude protein, total carbohydrate, protein efficiency ratio (PER), biological value (BV), true digestibility (TD), net protein utilization (NPU), essential amino acid composition, in-vitro protein digestibility (IVPD) and actual amino acid indices (essential amino acid index or amino acid score) were evaluated. Crude protein content was increased (8-149%), while total carbohydrate was decreased (11-62%) by germination, extraction and alpha-amylase treatments. Alpha-amylase treatment was more efficient in reducing total carbohydrate and increasing the protein content than that of extraction treatment. The protein quality of chick pea flours as measured by PER, BV, TD, NPU, IVPD and corrected amino acid indices (actual amino acid indices x IVPD) was significantly improved by these treatments. The protein quality of germinated-alpha-amylase treatment was comparable with casein, while germinated-alpha-amylase treaded seeds appeared nutritionally superior to casein. The results indicate that the germinated-alpha-amylase and germinated-alpha-amylase-extracted treatments could be used successfully as a source of concentrated high quality protein for baby food production. The corrected amino acid indices gave better prediction of PER, BV, TD and NPU (r = 93 to 97) than actual amino acid indices (r = 45 to 71). PER was highly correlated with corrected amino acid score (r = 0.93). The PER could be predicted from the following simple regression equation: PER = -1.827 + 0.0561 x corrected amino acid score.

Dietary Proteins↗
PubMed2005

Detection of single nucleotide polymorphisms in 24 kDa dimeric alpha-amylase inhibitors from cultivated wheat and its diploid putative progenitors.

Seventeen new genes encoding 24 kDa family dimeric alpha-amylase inhibitors had been characterized from cultivated wheat and its diploid putative progenitors. And the different alpha-amylase inhibitors in this family, which were determined by coding regions single nucleotide polymorphisms (cSNPs) of their genes, were investigated. The amino acid sequences of 24 kDa alpha-amylase inhibitors shared very high coherence (91.2%). It indicated that the dimeric alpha-amylase inhibitors in the 24 kDa family were derived from common ancestral genes by phylogenetic analysis. Eight alpha-amylase inhibitor genes were characterized from one hexaploid wheat variety, and clustered into four subgroups, indicating that the 24 kDa dimeric alpha-amylase inhibitors in cultivated wheat were encoded by multi-gene. Forty-five cSNPs, including 35 transitions and 10 transversions, were found, and resulted in a total of ten amino acid changes. The cSNPs at the first site of a codon cause much more nonsynonymous (92.9%) than synonymous mutations, while nonsynonymous and synonymous mutations were almost equal when the cSNPs were at the third site. It was observed that there was Ile105 instead of Val105 at the active region Val104-Val105-Asp106-Ala107 of the alpha-amylase inhibitor by cSNPs in some inhibitors from Aegilops speltoides, diploid and hexaploid wheats.

Amino Acid Sequence↗
PubMed2000

Structure, specificity and function of cyclomaltodextrinase, a multispecific enzyme of the alpha-amylase family.

Cyclomaltodextrinase (CDase, EC 3.2.1.54), maltogenic amylase (EC 3. 2.1.133), and neopullulanase (EC 3.2.1.135) are reported to be capable of hydrolyzing all or two of the following three types of substrates: cyclomaltodextrins (CDs); pullulan; and starch. These enzymes hydrolyze CDs and starch to maltose and pullulan to panose by cleavage of alpha-1,4 glycosidic bonds whereas alpha-amylases essentially lack activity on CDs and pullulan. They also catalyze transglycosylation of oligosaccharides to the C3-, C4- or C6-hydroxyl groups of various acceptor sugar molecules. The present review surveys the biochemical, enzymatic, and structural properties of three types of such enzymes as defined based on the substrate specificity toward the CDs: type I, cyclomaltodextrinase and maltogenic amylase that hydrolyze CDs much faster than pullulan and starch; type II, Thermoactinomyces vulgaris amylase II (TVA II) that hydrolyzes CDs much less efficiently than pullulan; and type III, neopullulanase that hydrolyzes pullulan efficiently, but remains to be reported to hydrolyze CDs. These three types of enzymes exhibit 40-60% amino acid sequence identity. They occur in the cytoplasm of bacteria and have molecular masses from 62 to 90 kDa which are slightly larger than those of most alpha-amylases. Multiple amino acid sequence alignment and crystal structures of maltogenic amylase and TVA II reveal the presence of an N-terminal extension of approximately 130 residues not found in alpha-amylases. This unique N-terminal domain as seen in the crystal structures apparently contributes to the active site structure leading to the distinct substrate specificity through a dimer formation. In aqueous solution, most of these enzymes show a monomer-dimer equilibrium. The present review discusses the multiple specificity in the light of the oligomerization and the molecular structures arriving at a clarified enzyme classification. Finally, a physiological role of the enzymes is proposed.

Amino Acid Sequence↗
PubMed2000

alpha-Amylase immobilized on bulk acoustic-wave sensor by UV-curing coating.

A new method for immobilization of alpha-amylase by UV-curing coating is proposed in this paper. The immobilization procedure of UV-curing coating on piezoelectric quartz crystal is simple and convenient, and causes less loss of enzymatic activity. The activity of the immobilized alpha-amylase is monitored by a technique based on bulk acoustic-wave (BAW) sensor. The frequency shift of BAW sensor can reflect the degree of hydrolysis of starch by the immobilized alpha-amylase. It is appropriate for the immobilized alpha-amylase to hydrolyze the soluble starch under pH 7.0 condition, which is similar to that of the free alpha-amylase. Kinetic parameters (the Michaelis constant, K(m), and the maximum initial rate V(max)) of the enzymatic hydrolysis of starch by the immobilized alpha-amylase are estimated by using a linear method of Lineweaver-Burk plot. K(m)=12.7mgml(-1) and V(max)=15.9Hzmin(-1). And the experimental results show that the immobilized alpha-amylase entrapped by the UV-curing coating retains adequate enzymatic activity and can be reused more than 50 times under certain experimental conditions.

Journal Article↗