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)

Phytase, an enzyme that degrades the phosphorus storage compound phytate, has the potential to enhance phosphorus availability in animal diets when engineered into soybean (Glycine max) seeds. The phytase gene from Aspergillus niger was inserted into soybean transformation plasmids under control of constitutive and seed-specific promoters, with and without a plant signal sequence. Suspension cultures were used to confirm phytase expression in soybean cells. Phytase mRNA was observed in cultures containing constitutively expressed constructs. Phytase activity was detected in the culture medium from transformants that received constructs containing the plant signal sequence, confirming expectations that the protein would follow the default secretory pathway. Secretion also facilitated characterization of the biochemical properties of recombinant phytase. Soybean-synthesized phytase had a lower molecular mass than did the fungal enzyme. However, deglycosylation of the recombinant and fungal phytase yielded polypeptides of identical molecular mass (49 kD). Temperature and pH optima of the recombinant phytase were indistinguishable from the commercially available fungal phytase. Thermal inactivation studies of the recombinant phytase suggested that the additional protein stability would be required to withstand the elevated temperatures involved in soybean processing.
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PMID:Secretion of active recombinant phytase from soybean cell-suspension cultures. 923 86

A 17-wk study was conducted to evaluate the effects of supplementing laying hen diets with a commercially produced microbial phytase. Hy-Line W-36 pullets (21 wk of age) were randomly allocated to 1 of 10 diets in a factorial arrangement of five levels of nonphytate phosphorus (0.1 to 0.5% NPP) and two levels of phytase (0 and 300 U/kg feed). Dietary metabolizable energy, protein, and calcium were maintained at 2,816 kcal/kg, 16.6%, and 4%, respectively. Criteria evaluated included egg production, feed consumption, egg weight, egg specific gravity, mortality, and various bone quality parameters. Feeding 0.1% NPP without supplemental phytase decreased egg production (hen-housed) 8.1% over the entire study and 29.6% over the last 4 wk, relative to other diets without supplemental phytase. Similarly, feed consumption of hens fed 0.1% NPP without phytase decreased 5.8% over 17 wk and 13.0% over the last 4 wk. Egg production and feed consumption were maintained at the level of other treatments without phytase when the 0.1% NPP diet was supplemented with phytase (82.1% and 82.4 g per hen per d, respectively). Egg weights and egg specific gravity decreased and mortality increased when hens consumed 0.1% NPP without phytase. Supplementing the 0.1% NPP diet with phytase completely corrected these adverse effects. No deficiency symptoms were observed in hens fed diets containing 0.2 to 0.5% NPP. Phytase supplementation of these diets gave no further improvements in performance.
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PMID:Performance of commercial laying hens fed various phosphorus levels, with and without supplemental phytase. 925 Nov 48

Annual nitrogen (N), phosphorus (P), and potassium (K) flows in agriculture in The Netherlands were identified and quantified in 1990, with special emphasis on pig production. Also, the effects that various management strategies in pig production have on NPK emission in 1990 were compared using a static deterministic simulation model. Ammonia emission from pig production in 1990 (60.9 Gg N) exceeded the defined target for the year 2000 (12.7 Gg N). Measures that affect volatilization of ammonia directly (i.e., introduction of low-emission stables, manure storage facilities, or manure application techniques) reduced ammonia emission most effectively. These measures, however, should be combined with a reduction in application of artificial N fertilizer to avoid an increase in N losses through leaching, run-off, or denitrification. Targets for ammonia emission in the year 2010 require a reduction in the pig population of 24 to 62%, in addition to implications of measures described in this article. National NPK losses in 1990 through leaching, run-off, or denitrification, predicted at 223.5 kg/ha for N, 32.7 kg/ha for P, and 67 kg/ha for K, exceeded government targets for the year 2010 (185 kg N/ha; 8.7 kg P/ha; norm not set for K). Reducing application of artificial NPK fertilizer reduced national NPK losses most effectively. For P, use of phytase and feeding pigs in accordance with their P requirements is required, in addition to limited use of artificial P fertilizer to meet targets for the year 2010. Hence, from an environmental point of view, pig production in The Netherlands is limited primarily by ammonia emission targets for the year 2010.
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PMID:Nutrient flows in agriculture in The Netherlands with special emphasis on pig production. 926 51

Two experiments were run to determine the digestibility of phosphorus in different vegetable and animal proteins for the pig diet. Each experiment comprised two 4 x 4 Latin squares run concurrently. Pigs initially weighing 30 kg were kept in metabolism crates and fed twice daily at about 2.5-fold metabolisable energy requirement for maintenance. A semi-purified basal diet low in phosphorus and without intrinsic phytase activity was fed either alone or after blending into mixtures with one of the ingredients to be tested. Mixtures were calculated to contain not more than 2 g digestible P/kg DM and between 5.0 and 6.0 g Ca/kg DM. Faeces and urine were quantitatively collected for 8 days after 7 days of adaptation. Phosphorus digestibility for ingredients under test was calculated assuming the digestibility of phosphorus from the basal diets to be constant in all diets. P digestibilities in solvent extracted soybean meal from dehulled seed, rapeseed and solvent extracted rapeseed meal were 37, 42 and 24%, respectively. Supplementation of a microbial phytase (750 U/kg diet) improved digestibility coefficients significantly to 76, 66 and 73%, respectively. Digestibility of phosphorus in 3 different batches of fish meal ranged from 85 to 90%, without significant differences between batches. In 3 different types of carcass meal, digestibility coefficients were 80, 82 and 83% without significant differences between types, and digestibility of phosphorus from bone meal was 80%.
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PMID:Digestibility of phosphorus in protein-rich ingredients for pig diets. 927 19

Two chick assays were conducted in an attempt to understand how 1alpha-hydroxylated cholecalciferol compounds [1,25-(OH)2 D3 and 1alpha-OH D3] function in chicks to improve utilization of phytate-bound phosphorus (P) and trace minerals. Mucosal tissue from chicks fed a P-deficient corn-soybean meal diet, with or without supplemental 1alpha-OH D3, was incubated with sodium phytate. Inorganic P (Pi) release from sodium phytate, a measure of mucosal phytase activity, was not influenced by 1alpha-OH D3 presence in the diet. Increasing doses of mucosal protein in tubes containing sodium phytate resulted in marked increases (P < 0.01) in Pi release, but 1alpha-OH D3 in the diet from which the duodenal mucosal tissue was obtained had no effect on Pi release. Similarly, addition of either 1alpha-OH D3 or 1,25-(OH)2 D3 directly to the incubation tubes had no effect on Pi production. Efficacy of supplemental 1alpha-OH D3 and phytase was also tested in cecectomized vs. sham-operated chicks that were fed P-deficient and cholecalciferol-adequate corn-soybean meal diets. Removal of the twin ceca was done in an attempt to remove much of the intestinal microbial activity, and in turn, much of the gut microbial phytase activity. Marked increases (P < 0.01) in bone ash occurred in response to phytase or 1alpha-OH D3 supplementation, and cecectomized birds responded to either addition in the same manner as sham-operated controls. The data suggest that the marked phytate-P releasing capacity of dietary 1alpha-OH D3 or 1, 25-(OH)2 D3 is not caused by an increased specific activity of intestinal phytase.
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PMID:1alpha-hydroxycholecalciferol does not increase the specific activity of intestinal phytase but does improve phosphorus utilization in both cecectomized and sham-operated chicks fed cholecalciferol-adequate diets. 931 64

This paper focuses on research with pigs carried out primarily at the ID-DLO in the Netherlands with the aim to reduce environmental pollution with nitrogen and phosphorus by changing the diet of the animals while maintaining their health and performance. The excretion of phosphorus (P) per growing pig has been more than halved in the last 20 years as a result of intensive nutritional research on P digestibility, requirements for P, and on the efficacy of microbial phytase in pig feeds. Also, nitrogen (N) excretion can be reduced substantially, but this knowledge has not been put into practice as yet. Preliminary results show that ammonia production can be reduced considerably by altering the diet. Studies to reduce the overproduction of sow manure (up to 98% water) showed that voluntary water consumption by non-pregnant sows under thermal neutral conditions was approximately 1.4 higher than the requirements. A water:feed ratio of 2:1 for pregnant sows kept at an ambient temperature of 18-20 degrees C had no detrimental effect on health and nutrient digestibility, but diminished urine production by 3.6 L/day, as compared to that with ad libitum water consumption.
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PMID:Impact of nutrition on reduction of environmental pollution by pigs: an overview of recent research. 932 55

In the nutrition of monogastric animals phytate-P represents a poorly available source of phosphorus, especially in the case of diets low in phytase activity. Similarly the bioavailability of different minerals and trace elements is considerably reduced by phytate complexes. High concentrations of Ca increase the anti-nutritive effect of phytic acid on mineral and trace element bioavailability and thus impede the action of phytase. This effect can in part be compensated by an increased supply of vitamin D. There is also evidence for protective functions of phytic acid such as the prevention of the formation of free radicals, the delaying of post prandial glucose absorption, the decrease in plasma cholesterol and triglycerides as well as a change in the carry over of heavy metals. The basic mechanisms by which phytic acid may exert these effects are still not clear. In several studies reported in the literature, evidence for the nutritional significance and ecological importance of microbial phytase for pigs and poultry has been given. As the monogastric organism contains no or only negligible amounts of endogenous phytase in the stomach and small intestine, it is therefore dependent on plant or microbial phytase. Plant phytase, e.g. from rye, triticale, wheat or, in smaller amounts from barley, and supplemented Aspergillus-phytase display cumulative effects.
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PMID:Nutritional significance of phytic acid and phytase. 934 95

Commercial and laboratory-strain crossbred chicks responded (P < .01) markedly to 1alpha-hydroxycholecalciferol (1alpha-OH D3) during the 2nd and 3rd wk of life. Bone-ash responses exceeded 50% when this compound was added at 20 microg/kg to phosphorus (P)-deficient corn-soybean meal diets containing surfeit levels (25 microg/kg) of cholecalciferol (D3). Phosphorus excretion was decreased (P < .01) and, thus, retention was increased (P < .01) when 1alpha-OH D3 was supplemented. A P-deficient (.10% P) casein-amino acid purified diet, devoid of D3, was used to determine whether 15 microg/kg of D3 was sufficient to facilitate optimal absorption of the nonphytate P contained in this diet. Bone ash responded to .075% P addition (KH2PO4), and chicks fed diets with .175% nonphytate P exhibited further bone-ash responses to 15 microg/kg of D3 or 10 microg/kg 1alpha-OH D3. Higher levels of either of these D3 compounds did not produce additional responses. This suggested that 15 to 25 microg/kg of D3 in a P-deficient corn-soybean meal diet (.28% phytate P and .14% nonphytate P) is more than adequate to facilitate optimal absorption of the nonphytate P present in the diet. A P-deficient casein-dextrose diet (.13% nonphytate P and 15 microg/kg D3) was fed in the final chick assay, and chicks fed this diet did not show bone ash responses to 1alpha-OH D3 or to microbial-derived phytase (1,470 units/kg). Thus, with P-deficient corn-soybean meal diets containing at least 15 microg D3/kg, 1alpha-OH D3 supplementation markedly increased weight gain and bone ash because it increased the utilization of phytate P.
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PMID:Utilization of phytate and nonphytate phosphorus in chicks as affected by source and amount of vitamin D3. 937 14

The kinetics, mineral dependency, and pH dependency of phytate hydrolysis by preparations of chicken small intestinal brush border membrane vesicles were determined. Substantial phytate hydrolysis occurred over the pH range from 5 to 6.5 with a maximum hydrolysis at pH of 6. Inclusion of 25 mM MgCl2 in the media doubled the rate of phytate hydrolysis. The brush border was shown to have no nonspecific acid phosphatase activity and excess phytate had no effect on alkaline phosphatase activity at pH 11. Under optimal conditions of pH 6 plus 25 mM MgCl2, a kinetic model of a single Michaelis-Menten type of enzymatic activity with a Km of 0.160 +/- 0.008 mM and a Vmax of 42.5 +/- 1.0 nmol/mg vesicle protein per min plus a small unsaturable component converged to the data (P < 0.05). The specific and total activities of intestinal brush border phytase were highest in the duodenum (P < 0.05) and decreased progressively down the length of the gut. Intestinal brush border vesicles prepared from broiler chicks and mature laying hens had comparable specific phytase activity. However, the total activity of brush border phytase was 35% higher in the small intestine of laying hens (P < 0.05). Intestinal brush border phytase could contribute to phytate-phosphorus digestibility and may be subject to regulation in response to the dietary phosphorus and vitamin D status of the chicken.
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PMID:Phytase activity in the small intestinal brush border membrane of the chicken. 956 39

Phytase hydrolyzes phytate to release inorganic phosphate, which would decrease the addition of phosphorus to feedstuffs for monogastric animals and thus reduce environmental pollution. The gene encoding phytase from Bacillus sp. DS11 was cloned in Escherichia coli and its sequence determined. A 560-bp DNA fragment was used as a probe to screen the genomic library. It was obtained through PCR of Bacillus sp. DS11 chromosomal DNA and two oligonucleotide primers based on N-terminal amino acid sequences of the purified protein and the cyanogen bromide-cleaved 21-kDa fragment. The phy cloned was encoded by a 2.2-kb fragment. This gene comprises 1152 nucleotides and encodes a polypeptide of 383 amino acids with a deduced molecular mass of 41,808 Da. Phytase was produced to 20% content of total soluble proteins in E. coli BL21 (DE3) using the pET22b(+) vector with the inducible T7 promoter. This is the first nucleic sequence report on phytase from a bacterial strain.
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PMID:Cloning of the thermostable phytase gene (phy) from Bacillus sp. DS11 and its overexpression in Escherichia coli. 959 81


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