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Query: EC:3.1.3.8 (phytase)
 1,997 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pH profiles of two microbial phytases were determined using four different general purpose buffers at different pH values. The roles of calcium chloride, sodium chloride, and sodium fluoride on activity were compared in these buffers. For Aspergillus niger phytase, calcium extended the pH range to 8.0. A high concentration of sodium chloride affected the activity of fungal phytase in the pH 3-4 range and shifted the pH optimum to 2.0 from 5.5 in Escherichia coli phytase. As expected, both of the microbial phytases were inhibited by sodium fluoride at acidic pH values. Because the Km for phytate increased nearly 2-fold for fungal phytase while Vmax increased about 75% in a high concentration of sodium chloride, it is possible that salt enhanced the product to dissociate from the active site due to an altered electrostatic environment. Modeling studies indicate that while the active site octapeptide's orientation is very similar, there are some differences in the arrangements of alpha-helices, beta-sheets, and coils that could account for the observed catalytic and salt effect differences.
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PMID:Salt effect on the pH profile and kinetic parameters of microbial phytases. 1839 37

Cryptococcus laurentii strain AL27 demonstrating significant potential for intracellular phytase production was selected by 2-step screening of Antarctic yeasts. The strain showed increased phytase activity in a culture medium with 40 g/L sucrose, KH2PO4 providing 5 mg/L phosphorus, and cultivation temperature of 24 degrees C, which relates it to psychrotrophic microorganisms. The enzyme kinetic characteristics according to sodium phytate were Km = 0.98 mmol/L, vlim = 33.3 micromol g(-1) min(-1). The enzyme had maximum activity at 40 degrees C and acted within a wide pH range: from 2.0 to 5.5, which is of positive significance for its direct inclusion into the feed of monogastric animals.
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PMID:Phytase from antarctic yeast strain Cryptococcus laurentii AL27. 1848 Dec 15

The phyA(m) gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichia pastoris in order to expand the pH profile of phytase and decrease the cost of production. The fusion phytase phyA(m)-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is (25.4+/-0.53) U/ml at the flask scale and (159.1+/-2.92) U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 degrees C and an optimal pH at 5.5~6.0 and its relative activity remains at a relatively high level of above 70% in the range of pH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 degrees C to 95 degrees C for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After deglycosylation by endoglycosidase H (EndoH(f)), the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those of phyCs and phyA(m).
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PMID:Expression, purification and characterization of a phyA(m)-phyCs fusion phytase. 1860 Jul 83

Phytase liberates inorganic phosphate from phytic acid (myo-inositol hexakisphosphate) which is the major phosphate reserve in plant-derived foods and feeds. An industrial strain of Saccharomyces cerevisiae expressing the Debaryomyces castellii phytase gene (phytDc) and D. occidentalis alpha-amylase gene (AMY) was developed. The phytDc and AMY genes were constitutively expressed under the ADC1 promoter in S. cerevisiae by using the delta-integration system, which contains DNA derived exclusively from yeast. The recombinant industrial strain secreted both phytase and alpha-amylase for the efficient degradation of phytic acid and starch as main components of plant seeds. This new strain hydrolyzed 90% of 0.5% (w/v) sodium phytate within 5 days of growth and utilized 100% of 2% (w/v) starch within 48 h simultaneously.
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PMID:Simultaneous degradation of phytic acid and starch by an industrial strain of Saccharomyces cerevisiae producing phytase and alpha-amylase. 1862 38

The present article deals with the studies on the effect of media ingredients, such as carbon, nitrogen, inorganic phosphates, surfactants, and metal salts, on phytase enzyme production by Aspergillus niger CFR 335 in submerged (SmF) and solid-state fermentations (SSF). The results obtained showed a 1.5-fold higher enzyme yield in the presence of sucrose in both SmF and SSF, while peptone was found to be a favorable nitrogen source for SmF. Sodium dihydrogen phosphate (NaH(2)PO(4)) favored 34% higher enzyme yield than the control, which was followed by 19% higher activity in potassium dihydrogen phosphate (KH(2)PO(4)) in SSF at 0.015% w/v. The addition of Tween-20 in SmF showed a maximum yield of 12.6 U/mL while, SDS suppressed the growth of the fungus. None of the surfactants favored the enzyme yield in SSF. Calcium chloride (CaCl(2)) was extensively efficient in stimulating more than 55% higher phytase production in SmF at 0.01% v/v. In SSF, none of the metal salts stimulated phytase production.
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PMID:Effect of different cultural conditions for phytase production by Aspergillus niger CFR 335 in submerged and solid-state fermentations. 1866 3

A novel phytase gene, appA, was isolated by degenerate polymerase chain reaction (PCR) and thermal asymmetric interlaced PCR from Dickeya paradisiaca. The full-length appA comprises 1278 bp and encodes 425 amino acid residues, including a 23-residue putative N-terminal signal peptide. The deduced amino acid sequence of appA reveals the conserved motifs RHGXRXP and HD, which are typical of histidine acid phosphatases; significantly, APPA shows maximum identity (49%) to a phytase from Klebsiella pneumoniae. To characterize the properties of APPA, appA was expressed in Escherichia coli and purified. The purified recombinant APPA has two pH optima at pH 4.5 and 5.5, optimum temperature at 55 degrees C, specific activity of 769 U/mg, and good pH stability. The K(m) value for the substrate sodium phytate is 0.399 mM with a Vmax of 666 U/mg. To our knowledge, this is the first report of a phytase or phytase gene isolated from Dickeya.
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PMID:Gene cloning, expression, and characterization of a novel phytase from Dickeya paradisiaca. 1867 91

The role of dietary phytate (inositol hexaphosphate) in the regulation of intestinal mucosa phytase was investigated in chicks. Seven-day-old chicks were grouped by weight into six blocks of three cages with six birds per cage. Three purified diets [a chemically defined casein diet, a chemically defined casein diet plus sodium phytate (20 g/kg diet) and a chemically defined casein diet plus sodium phytate (20 g/kg diet) and microbial phytase (1000 units/kg diet)] were randomly assigned to cages within each block. Chicks were fed experimental diets from 8 to 22 days of age then killed, and duodenal mucosa and left tibia removed. Phytase activity in duodenal mucosa, growth performance and bone ash content were determined. Addition of phytate to the chemically defined casein diet reduced (p < 0.05) the V(max) of the duodenal brush border phytase, but the K(m) of the enzyme was not affected. Addition of phytate also reduced (p < 0.05) weight gain, feed intake, feed efficiency and percentage ash. Addition of microbial phytase fully restored the feed efficiency (p < 0.05), but V(max) and body weight gain were only partially restored (p < 0.05). In conclusion, it would seem that dietary phytates non-competitively inhibit intestinal mucosa phytase.
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PMID:Dietary phytate (inositol hexaphosphate) regulates the activity of intestinal mucosa phytase. 1870 Aug 51

The effect of dietary phytate and phytase on carbohydrase activity and hexose transport was investigated in broiler chickens. Diets containing phytate P (2.2 or 4.4 g/kg) with different phytase dose rates (0, 500, or 1,000 phytase units/kg) were fed to 504 female Cobb chicks for 3 wk. Diets containing high phytate concentrations depressed (P < 0.05) BW and G:F, whereas phytase supplementation improved (P < 0.05) the performance of birds. In the duodenum, phytate decreased (P < 0.05) the activities of disaccharidases, Na(+)K(+)-ATPase, and glucose concentrations by 5 to 11%, but phytase enhanced (P < 0.05) the concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose by 5 to 30%. In the jejunum, phytate decreased (P < 0.05) the concentrations of amylase, sucrase, Na(+)K(+)-ATPase, and glucose by 10 to 22%, and phytase alleviated the negative effect of phytate on the above variables. Ingestion of diets containing phytate also decreased (P < 0.05) serum amylase activity and glucose concentration, and phytase enhanced (P < 0.05) serum concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose. There were also interactions (P < 0.05) between phytate and phytase on the concentrations of serum amylase, duodenal amylase, sucrase, and jejunal glucose. Enzymatic analysis at a molecular level showed that neither phytate nor phytase influenced the mRNA expression of sucrase-isomaltase in the small intestine. Also, the investigation into the sodium glucose cotransporter gene may challenge the mechanism by which phytate interferes with glucose utilization, as partly indicated by bird performance, and transmembrane transport because diets containing increased phytate upregulated (P < 0.05) the mRNA expression of the sodium glucose cotransporter gene in duodenum and did not influence it in the jejunum. These results indicate that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.
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PMID:Effect of diet containing phytate and phytase on the activity and messenger ribonucleic acid expression of carbohydrase and transporter in chickens. 1870 94

The effects of phytic acid and 2 sources of exogenous phytase (bacterial vs. fungal) on the flow of endogenous amino acids at the terminal ileum of broilers were assessed using the enzyme-hydrolyzed casein method. Phytic acid (as the sodium salt) was included in a purified diet at 8.5 and 14.5 g/kg, and each diet was fed without or with a fungal (Aspergillus niger-derived) or a bacterial (Escherichia coli-derived) microbial phytase at 500 phytase units/kg of diet. Increasing the concentration of phytic acid in the diet from 8.5 to 14.5 g/kg increased (P < 0.001) the flow of all measured amino acids by an average of 68%, with a range from 17% for proline to 145% for phenylalanine. The flow of endogenous aspartic acid, serine, glutamic acid, glycine, leucine, tyrosine, phenylalanine, and histidine were increased by more than the mean, indicating changes in the composition of endogenous protein in response to the presence of higher concentrations of phytic acid. Supplementation of both phytases reduced (P < 0.001) the flow of endogenous amino acids, but the reduction (P = 0.06) was greater for the bacterial phytase compared with the fungal phytase. These data suggest that a substantial part of the amino acid and energy responses observed following phytase supplementation in broiler chickens stems from reduced endogenous amino acid flows and that the capacity of different phytases to counteract the antinutritive properties of phytic acid vary.
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PMID:Influence of dietary phytic acid and source of microbial phytase on ileal endogenous amino acid flows in broiler chickens. 1893 Nov 80

Forty-eight grower pigs were used to evaluate the effects of feeding low phytic acid (LPA) corn, LPA soybean meal, normal corn (NC), normal soybean meal (NSBM), and phytase on nutrient digestibility and excretion. Barrows were blocked by BW (initial BW=45.3+/-1.6 kg) and randomly assigned to 1 of 8 dietary treatments in a 2 x 2 x 2 factorial arrangement (6 pigs/treatment). Pigs were fed twice daily (0700 and 1700 h) at 3 times the ME requirement for maintenance. Phytase was added to the diet at 510 phytase units/kg of feed (where 1 phytase unit is the quantity of enzyme that liberates 1 mumol of inorganic P/min from 0.005 mol/L of sodium phytate at pH 5.5 and 37 degrees C), at the expense of corn starch, and all diets were formulated to provide 0.39% total P, 0.50% Ca, and 1.0% lysine with no supplemental inorganic P. Pigs were adapted to metabolism crates and dietary treatments for 7 d, followed by a 3-d total collection of urine and feces. Total fecal DM excreted, percentage of DM of feces, and percentage of DM digested were not different (P>0.53) among treatments. Fecal P excretion was reduced for pigs fed LPA corn vs. NC (2.85 vs. 3.24+/-0.119 g/d; P=0.024), for pigs fed LPA soybean meal vs. NSBM (2.79 vs. 3.30+/-0.119 g/d; P=0.007), for pigs fed phytase vs. nonphytase diets (2.80 vs. 3.29+/-0.119 g/d; P=0.009), and for pigs fed LPA corn, LPA soybean meal, and phytase vs. NC and NSBM without phytase (2.16 vs. 3.70+/-0.237 g/d; P<0.001). Phosphorus digestibility was increased for pigs fed diets containing LPA corn vs. NC (48.4 vs. 39.9+/-2.27%; P=0.012), for pigs fed phytase vs. nonphytase diets (48.4 vs. 39.9+/-2.27%; P=0.019), and for pigs fed the LPA corn, LPA soybean meal, and phytase diet vs. the NC and soybean meal diet (60.1 vs. 34.1+/-4.5%; P<0.001) and tended to be increased for pigs fed LPA soybean meal vs. NSBM (47.2 vs. 41.1+/-2.27%; P=0.075). Corn type and soybean meal type had no effect (P>0.11) on water-soluble P excretion. However, pigs fed diets containing phytase tended to excrete less total water-soluble P than those without phytase inclusion (1.99 vs. 2.27+/-0.099 g/d; P<0.066). This study demonstrates that feeding any combination of LPA corn, LPA soybean meal, and phytase was additive, significantly improving P digestibility and dramatically decreasing P excretion to reduce the potential impacts of P from pig manure on the environment.
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PMID:Effects of low-phytic acid corn, low-phytic acid soybean meal, and phytase on nutrient digestibility and excretion in growing pigs. 1902 41


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