Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.
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PMID:Soybeans transformed with a fungal phytase gene improve phosphorus availability for broilers. 962 38

Phytase catalyses the release of phosphate from phytate (myo-inositol hexakisphosphate), the predominant form of phosphorus in cereal grains, oilseeds and legumes. The presence of phytase activity was investigated in 334 strains of 22 species of obligately anaerobic ruminal bacteria. Measurable activities were demonstrated in strains of Selenomonas ruminantium, Megasphaera elsdenii, Prevotella ruminicola, Mitsuokella multiacidus and Treponema spp. Strains isolated from fermentations with cereal grains proved to have high activity, and activity was particularly prevalent in S. ruminantium, with over 96% of the tested strains being positive. The measured phytase activity was found exclusively associated with the bacterial cells and was produced in the presence of approximately 14 mM phosphate. The most highly active strains were all S. ruminantium, with the exception of the one Mitsuokella multiacidus strain examined. Phytase activity varied greatly among positive strains but activities as high as 703 nmol phosphate released (ml culture)-1 were measured for a S. ruminantium strain and 387 nmol phosphate released (ml culture)-1 for the Mitsuokella multiacidus strain.
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PMID:Phytase activity of anaerobic ruminal bacteria. 963 27

Crossbred weanling pigs (an equal number of barrows and gilts) with an average initial weight of 7.4 (Exp. 1) or 9.6 kg (Exp. 2) were used in two 4-wk experiments (Exp. 1, n = 96; Exp. 2, n = 96) to investigate the effects of added phytase or citric acid on performance, rib mineralization, gastric pH, and digestibility measurements. A corn-soybean meal-based diet low in Ca and P was used in both experiments. In Exp. 1, three citric acid levels (0, 1.5, or 3.0%) and four phytase levels (0, 250, 500, or 750 U/kg) were used in a 3 x 4 factorial arrangement of treatments. In Exp. 2, two citric acid levels (0 or 2.0%) and three phytase levels (0, 250, or 500 U/kg) were used in a 2 x 3 factorial arrangement of treatments. Phosphorus was maintained at .33 and .34% in Exp. 1 and 2, respectively. Calcium was maintained at a 2.5:1 ratio with total available P (available P plus the estimated released phytate P by phytase) in Exp. 1 and at a level of .44% in Exp. 2. In both experiments, BW and feed consumption were measured weekly, and pen fecal samples were collected twice daily for 5 d during wk 4. At the end of wk 4, the barrow in each pen was killed following a fast-refeed-fast (22-1-2 h) regimen for collection of 10th ribs and stomach digesta. In Exp. 1 and 2, phytase addition did not affect (P > .05) performance but linearly increased (P < .05) rib shear force, shear energy, dry bone weight, ash weight, ash percentage, and Ca and P digestibilities. Addition of citric acid in both experiments reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved (P < .05) ADG, feed efficiency, and Ca digestibility in Exp. 1, but it had no effect on performance and Ca digestibility in Exp. 2. In summary, the additions of citric acid and phytase to weanling pig diets were each beneficial, but no synergistic effects were observed.
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PMID:The effects of microbial phytase, citric acid, and their interaction in a corn-soybean meal-based diet for weanling pigs. 969 Jun 44

A feeding trial was performed using 4 x 60 day-old chickens (Ross 208 cockerels) raised up to 42 days of age to determine whether exogenous phytase addition increases phosphorus utilisation by broiler chickens, and to assess its effects on some production traits as well as on the ash content and mechanical stability of the tibia. The chickens' feed consisted of maize, wheat, soybean meal, fish meal, yeast, and fat powder. The basic feed was supplemented with inorganic phosphorus in groups A and B. In groups C and D, the amount of the inorganic phosphorus supplement (DCP) was decreased by 50%, at the same calcium/phosphorus ratio. The 50% reduction of inorganic phosphorus supplementation represents a 20% decrease of total phosphorus. To the diets of groups B and D a phytase enzyme preparation (Phytase Novo CT) was added. The calculated exogenous phytase activity was 600 FYT/kg feed. The decrease of inorganic phosphorus did not cause significant differences in the daily weight gain but lowered the feed conversion rate by 10%. Calcium and phosphorus excretion decreased by 18% and 15%, and the breaking strength of the tibia was also lower. Phytase supplementation of the feed at a lower rate of inorganic phosphorus supplementation did not cause changes in the body weight gain but improved the feed conversion rate by 5.6%. Phosphorus and calcium output decreased by 21% and 11%, respectively, but chemical composition and mechanical stability of the tibia were unaltered.
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PMID:Effects of phytase supplementation on calcium and phosphorus output, production traits and mechanical stability of the tibia in broiler chickens. 970 26

Phytic-phosphorus has a very low bioavailability for monogastric animals and the non-utilized mineral contributes to the phosphorus (P) pollution problems. Phytases may ameliorate phytic-P antinutritive properties. However, phytases are very sensitive to the pelleting temperature commonly used for compound feed production and thus the challenge to produce a more thermostable phytase is very important. Pure Aspergillus fumigatus phytase (AFP) has the ability to refold into a native-like fully active structure after heat denaturation (20 min at 90 degrees C). The aim of the present work was to evaluate in vitro (in feed) and in vivo in young and in growing-finishing pigs the effects of AFP included in the feed at a level of 500 U/kg. Feed supplementation with AFP resulted in an in vitro phosphorus release of about three times higher than that obtained from the basal diets, irrespective of the pH value used for the determination (5.5 or 7). When the supplemented feed was steam pelleted at about 84 degrees C, the free P obtained after incubation at pH 5.5 represented 53% on an average of that obtained from the corresponding mash diets. The phytic-P-rich diets systematically induced hypophosphataemia, hypercalcaemia and hyperphosphatasaemia. The normal blood levels of P, Ca and alkaline phosphatase were restored by AFP. P apparent digestibility was significantly higher for the AFP diet (52.8 versus 30.8%). The improvement in Ca digestibility was not statistically significant. In all three in vivo experiments, AFP significantly decreased the P concentration in faeces (between 13 and 33%) as well as increased the growth rate and decreased the feed conversion ratio. Bone strength was significantly higher in the growing-fattening pigs fed on the AFP diet.
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PMID:Effects of Aspergillus fumigatus phytase on phosphorus digestibility, phosphorus excretion, bone strength and performance in pigs. 979 86

Two trials were conducted to determine the effects on broiler chicken performance and health of reducing dietary phosphorus levels by treating feed with the enzyme phytase, formulating diets using high available phosphorus (HAP) corn, or when diets were formulated with HAP corn and treated with phytase. Cobb x Cobb male broiler chickens were placed in an experimental design consisting of four dietary treatments with six replicate pens of 50 broilers per pen. The dietary treatments consisted of untreated control feed, phytase-supplemented feed (500 U/kg), diets prepared with HAP corn, and diets prepared with HAP corn and supplemented with phytase. The chickens were maintained on these dietary treatments from 1 to 49 d of age with feed and water made available for ad libitum consumption. When the two trials were combined, there was a significant (P < or = 0.05) increase in body weight in the broilers fed the phytase treated diets at 49 d of age. The serum activity of alkaline phosphatase was significantly decreased in the diets supplemented with phytase, and serum cholesterol was significantly decreased in the diets prepared with HAP corn. These data indicate that total phosphorus can be reduced by at least 11% in diets prepared with HAP corn, or in diets supplemented with phytase, without affecting the performance or health of broiler chickens. When diets are prepared with HAP corn and supplemented with phytase, the dietary addition of total phosphorus can be reduced by at least 25% without affecting broiler chicken performance or health.
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PMID:Effect of dietary phytase and high available phosphorus corn on broiler chicken performance. 987 94

1. In the first of 2 experiments ducklings grown from 2 to 19 d were given diets with 0, 200 or 400 g rice bran, with or without a phytase and with 1 or 3 g inorganic phosphorus (Pi) per kg for rice bran-based diets only. In the 2nd experiment rice bran concentrations were 0, 300 or 600 g rice bran per kg with or without a phytase and 1 g Pi/kg. Ducks were grown from 19 to 40 d of age. 2. In experiment 1, a response to phytase was observed for weight gain and food intake on most diets except those with 200 g rice bran (3 g Pi) and 4.00 g rice bran (1 g P)i/kg. Main effects showed that 400 g rice bran depressed growth rate and food conversion ratio (FCR); increasing Pi depressed food intake, while food phytase increased food intake and growth rate over 2 to 19 d. There were several interactions. Dry matter and P retention were reduced but N digestibility improved when rice bran was increased from 200 g to 400 g/kg at 2 to 10 d of age; apparent metabolisable energy (AME) and calcium retentions were improved, similar results being seen at 10 to 19 d of age. Calcium and P retentions increased with the addition of food phytase and, at 10 to 19 d of age, phytase increased dry matter digestibility. Increasing Pi improved calcium and P retention, but only at 2 to 10 d of age. 3. Tibia ash (g or g/kg) content of bone was lowest on the diet without rice bran and without phytase; Pi concentration had no effect but phytase increased tibia ash on diets with 0 and 200 g rice bran and 1 g Pi/kg. Retention of several minerals in tibia ash declined at the highest rice bran inclusion rate; Pi level and phytase both increased Mg retention. 4. In experiment 2, food intake and growth rate of ducks, but not FCR, declined as rice bran inclusion increased from 0 to 600 g/kg. Phytase improved growth rate but not food intake and FCR on all 3 diets. Dry matter digestibility declined with increasing rice bran inclusion, but AME increased; retention of P and Mg declined but those of Ca and Fe increased. Phytase improved dry matter digestibility and retention of N and P. AME also increased but this was only on diets with 0 and 600 g rice bran/kg. There were reductions of 8% and 10% in P excreted in experiments 1 and 2 respectively when food phytase was added. 5. Tibia ash declined with increasing dietary inclusion of rice bran. Zn and Mn in ash tended to decline and Mg to increase; Ca and P showed no change in concentration in tibia ash. Again, phytase increased tibia ash content in bone. 6. It was concluded that there were a number of unexpected benefits from adding a food phytase to these diets, which resulted in improved nutrient yield and bird performance, although several of the diets appeared to be adequate in available P.
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PMID:Strategies to improve the nutritive value of rice bran in poultry diets. III. The addition of inorganic phosphorus and a phytase to duck diets. 992 12

Phytases (myo-inositol hexakisphosphate phosphohydrolases) are found naturally in plants and microorganisms, particularly fungi. Interest in these enzymes has been stimulated by the fact that phytase supplements increase the availability of phosphorus in pig and poultry feed and thereby reduce environmental pollution due to excess phosphate excretion in areas where there is intensive livestock production. The wild-type phytases from six different fungi, Aspergillus niger, Aspergillus terreus, Aspergillus fumigatus, Emericella nidulans, Myceliophthora thermophila, and Talaromyces thermophilus, were overexpressed in either filamentous fungi or yeasts and purified, and their biophysical properties were compared with those of a phytase from Escherichia coli. All of the phytases examined are monomeric proteins. While E. coli phytase is a nonglycosylated enzyme, the glycosylation patterns of the fungal phytases proved to be highly variable, differing for individual phytases, for a given phytase produced in different expression systems, and for individual batches of a given phytase produced in a particular expression system. Whereas the extents of glycosylation were moderate when the fungal phytases were expressed in filamentous fungi, they were excessive when the phytases were expressed in yeasts. However, the different extents of glycosylation had no effect on the specific activity, the thermostability, or the refolding properties of individual phytases. When expressed in A. niger, several fungal phytases were susceptible to limited proteolysis by proteases present in the culture supernatant. N-terminal sequencing of the fragments revealed that cleavage invariably occurred at exposed loops on the surface of the molecule. Site-directed mutagenesis of A. fumigatus and E. nidulans phytases at the cleavage sites yielded mutants that were considerably more resistant to proteolytic attack. Therefore, engineering of exposed surface loops may be a strategy for improving phytase stability during feed processing and in the digestive tract.
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PMID:Biophysical characterization of fungal phytases (myo-inositol hexakisphosphate phosphohydrolases): molecular size, glycosylation pattern, and engineering of proteolytic resistance. 992 54

Supplementation with phytase is an effective way to increase the availability of phosphorus in seed-based animal feed. The biochemical characteristics of an ideal phytase for this application are still largely unknown. To extend the biochemical characterization of wild-type phytases, the catalytic properties of a series of fungal phytases, as well as Escherichia coli phytase, were determined. The specific activities of the fungal phytases at 37 degreesC ranged from 23 to 196 U. (mg of protein)-1, and the pH optima ranged from 2.5 to 7.0. When excess phytase was used, all of the phytases were able to release five phosphate groups of phytic acid (myo-inositol hexakisphosphate), which left myo-inositol 2-monophosphate as the end product. A combination consisting of a phytase and Aspergillus niger pH 2.5 acid phosphatase was able to liberate all six phosphate groups. When substrate specificity was examined, the A. niger, Aspergillus terreus, and E. coli phytases were rather specific for phytic acid. On the other hand, the Aspergillus fumigatus, Emericella nidulans, and Myceliophthora thermophila phytases exhibited considerable activity with a broad range of phosphate compounds, including phenyl phosphate, p-nitrophenyl phosphate, sugar phosphates, alpha- and beta-glycerophosphates, phosphoenolpyruvate, 3-phosphoglycerate, ADP, and ATP. Both phosphate liberation kinetics and a time course experiment in which high-performance liquid chromatography separation of the degradation intermediates was used showed that all of the myo-inositol phosphates from the hexakisphosphate to the bisphosphate were efficiently cleaved by A. fumigatus phytase. In contrast, phosphate liberation by A. niger or A. terreus phytase decreased with incubation time, and the myo-inositol tris- and bisphosphates accumulated, suggesting that these compounds are worse substrates than phytic acid is. To test whether broad substrate specificity may be advantageous for feed application, phosphate liberation kinetics were studied in vitro by using feed suspensions supplemented with 250 or 500 U of either A. fumigatus phytase or A. niger phytase (Natuphos) per kg of feed. Initially, phosphate liberation was linear and identical for the two phytases, but considerably more phosphate was liberated by the A. fumigatus phytase than by the A. niger phytase at later stages of incubation.
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PMID:Biochemical characterization of fungal phytases (myo-inositol hexakisphosphate phosphohydrolases): catalytic properties. 992 55

Economical and thermostable phytase enzymes are needed to release phytate-phosphorus in plant foods for human and animal nutrition and to reduce phosphorus pollution of animal waste. Our objectives were to determine if a methylotrophic yeast, Pichia pastoris, was able to express a phytase gene (phyA) from Aspergillus niger efficiently and if suppression of glycosylation by tunicamycin affected its functional expression. The gene (1.4 kb) was inserted into an expression vector pPICZalphaA with a signal peptide alpha-factor, under the control of AOX1 promoter. The resulting plasmid was transformed into two P. pastoris strains: KM71 (methanol utilization slow) and X33 (wild-type). Both host strains produced high levels of active phytase (25-65 units/ml of medium) that were largely secreted into the medium. The expressed enzyme was cross-reacted with the polyclonal antibody raised against the wild-type enzyme and showed two pH optima, 2.5 and 5.5, and an optimal temperature at 60 degrees C. Compared with the phyA phytase overexpressed by A. niger, this phytase had identical capacity in hydrolyzing phytate-phosphorus from soybean meal and slightly better thermostability. Deglycosylation of the secreted phytase resulted in reduction in the size from 95 to 55 kDa and in thermostability by 34%. Tunicamycin (20 microg/ml of medium) resulted in significant reductions of both intracellular and extracellular phytase activity expression. Because there was no accumulation of intracellular phytase protein, the impairment did not seem to occur at the level of translocation of phytase. In conclusion, glycosylation was vital to the biosynthesis of the phyA phytase in P. pastoris and the thermostability of the expressed enzyme.
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PMID:Role of glycosylation in the functional expression of an Aspergillus niger phytase (phyA) in Pichia pastoris. 1008 68


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