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)

Of all the sources of phytase that have been studied (plant, animal, and microorganisms), the highest yields are produced by a wild-type strain A. niger NRRL 3135 (12.7 mg P/hr/ml = 6.8 microns P/ml/min = 113.9 nKat/ml) in a mineral salt medium in which total phosphate (4 mg %) is limiting for growth and cornstarch and glucose are the carbon sources. Synthesis of the enzyme is repressed by phosphate in the wild-type strain. Aspergillus niger NRRL 3135 produces two phytases one with pH optima at 2.5 and 5.5 (phyA) and one with an optimum at pH 2.0 (phyB). It also produces a pH 6.0 optimum phosphatase that has no phytase activity. These three glycoproteins have been purified to homogeneity, characterized, sequenced, and cloned. The sequences have been compared to each other, other phytases, and to known phosphatases. Their homology has been determined. The active sites of phytases show remarkable homology to the active site residues of the members of a particular class of acid phosphatase (histidine phosphatase). The most conserved sequence is RHGXRXP. Phytase has been covalently immobilized on Fractogel TSK HW-75 F and glutaraldehyde-activated silicate. It has been immobilized on agarose. Losses of activity have been noted on immobilization but these may be minimized by future research. It should be possible to commercially produce and recover penta-, tetra-, tri-, di-, and monoinositol phosphates using immobilized phytase if markets develop for those products. Phytase (phyA) from A. niger NRRL 3135 has been cloned into an A. niger glucoamylase producing strain CBS 513.88 using a construct that has a glucoamylae promoter and an A. niger NRRL 3135 leader sequence, and that is devoid of phosphate repression. The yield of the secreted enzyme was increased 52-fold above that of wild-type A. niger NRRL 3135. The bioengineered organism produces 270 microns P/ml/min (4500 nKat/ml) which is approximately 7.9 g/liter in the medium. The yield of the secreted enzyme was increased 1440-fold above that of wild type CBS 513.88. Commercial preparations of the cloned enzyme are available. Phytase (phyA) has been cloned into tobacco and canola. The enzyme is localized in the seed and expressed at high levels. Feeding of the seed to animals has made the phytin-P in the commercial diets available to the animals. The efficacy of feeding phytase to monogastric animals (poultry and swine) has been established. The amount of enzyme that is necessary to be added to commercial diets has been titred for broilers, layers, turkeys, ducks, and swine. The units of enzyme required are related to the phytin-P content in the diet. The use of the enzyme as a feed additive has been cleared in 22 countries. If phytase were used in the diets of all of the monogastric animals reared in the U.S., it would release phosphorus that has a value of $1.68 x 10(8) per year. The FDA has approved the enzyme preparation as GRAS. The effect of feeding phytase to animals enables assimilation of the P found in feed ingredients and diminishes the amount of phosphate in the manure and subsequently entering the environment. The effect of feeding phytase to animals on pollution has been quantitatively determined. If phytase were used in the diets of all of the monogastric animals reared in the United States, it would preclude 8.23 x 10(7) kg P from entering the environment.
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PMID:Phytase. 886 87

Ninety-six crossbred young pigs (body weight 7.8 kg) were used in a 5-week trial to determine the effectiveness of microbial phytase (EC 3.1.3 26) in improving the bioavailabilities of P and other nutrients in maize-soyabean-meal diets and, thus, replacing inorganic P with phytase. A 2 x 5 factorial arrangement of treatments was employed with two available P (aP) levels (0.7 and 1.6 g/kg) and five phytase levels (0, 350, 700, 1050, 1400 U (the quantity of enzyme that liberates 1 mumol inorganic phosphate/min from 5.1 mm-sodium phytate at pH 5.5 and 37 degrees)/kg diet). In addition, two extra diets were formulated to supply the National Research Council (1988) recommended level of aP (3.2 g/kg) with 0 or 1400 U phytase. The addition of graded levels of phytase resulted in linear increases in average daily weight gain, average daily feed intake and weight gain:feed intake for pigs fed on diets containing 0.7 or 1.6 g aP/kg (P < 0.04). Also, the addition of phytase linearly increased apparent digestibilities of P and Ca (P < 0.01), whereas faecal P excretion was linearly decreased (P < 0.01). Linear increases in shear force, shear energy and ash content of both the metacarpal and tenth rib, and shear stress of the metacarpal were found to respond to added phytase (P < 0.01). These improvements in performance, apparent P absorption and bone measurements by phytase were also observed by increasing dietary aP levels for most measurements. Adding 1400 U phytase to the 3.2 g aP/kg diet further increased average daily weight gain, average daily feed intake, apparent absorption of P, Ca and N and metatarsal shear force and ash content (P < 0.01 to 0.05). Generally, maximum responses occurred at a phytase level of 1050 U/kg diet for the 0.7 g aP/kg diets and 700 U for the 1.6 g aP/kg diets. Based on non-linear and linear response equations generated for the phytase and aP levels, the average function of the equivalency of P (Y, g/kg) v. microbial phytase (X, U/kg) was developed across aP levels of 0.7 and 1.6 g/kg for average daily weight gain and apparent digestibility of P: Y = 2.622-2.559e 0.00185X. The replacement of 1 g inorganic P as defluorinated phosphate would require about 246 U microbial phytase. This represents 41% of released P from phytate.
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PMID:Replacement of inorganic phosphorus by microbial phytase for young pigs fed on a maize-soyabean-meal diet. 894 63

Though the application of the toxic heavy metal cadmium is reduced, its concentration in soil and in feed still increases. Especially smoking habits and unbalanced diets cause cadmium intake in humans beyond the limits suggested by WHO. One possibility to reduce cadmium burden is to influence the bioavailability of cadmium in the feed by certain vitamins, trace elements and other feed components and thus to lower its content in food from animal origin. In the present study the influence of vitamin C and phytase on the bioavailability of cadmium was investigated in broiler chicken. It was shown that 1 g vitamin C per kg of feed lowered cadmium accumulation in kidney and in liver by up to 40%. Addition of phytase, a new feeding enzyme, licensed in 1992 in Germany for improving phosphate utilization from phytate, lowered cadmium accumulation by up to 60%. Therefore the addition of these two components to the feed lowers the cadmium burden in food from animal origin and thus increases its quality.
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PMID:[Bioavailability of cadmium: effect of vitamin C and phytase in broiler chickens]. 899 92

Phytases catalyse the hydrolysis of phytate (myo-inositol hexakisphosphate) to myo-inositol and inorganic phosphate. In this study genes encoding novel phytases from two different filamentous fungi, Aspergillus terreus strain 9A-1 and Myceliophthora thermophila were isolated. The encoded PhyA phytase proteins show 60% (A. terreus) and 48% (M. thermophila) identity, respectively, to the PhyA of Aspergillus niger and have 21-29% identity compared to other histidine acid phosphatases. All three PhyA proteins, in contrast to the A. niger pH 2.5-optimum acid phosphatase, prefer phytic acid as substrate and show enzyme activity at a broad range of acidic pH values. Based on their enzyme characteristics and protein sequence homology, the phytases form a novel subclass of the histidine acid phosphatase family.
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PMID:The phytase subfamily of histidine acid phosphatases: isolation of genes for two novel phytases from the fungi Aspergillus terreus and Myceliophthora thermophila. 902 98

During germination, maize seedlings express a phytase able to hydrolyse the large amount of phytin stored in the dry seed. Previous studies allowed purification and characterization of this enzyme as a homodimer of 38 kDa subunits [Laboure, Gagnon and Lescure, Biochem. J. (1993) 295, 413-419]. In the present work, an antibody against the purified maize phytase has been used to screen a maize seedling cDNA expression library. Several positive clones containing an insert of about 1400 bp were isolated. The nucleotide sequence of the insert of one of these clones has been established. This cDNA, called phy S11, was 1335 bp long and contained an open reading frame of 387 amino acids. The sequence of N-terminal residues (23 amino acids) of the purified phytase has been established. These residues are found at positions 19-41 of the amino acid sequence encoded by phy S11. This confirms that this cDNA codes for the maize phytase. The deduced amino acid sequence appears to be very different from those of published Aspergillus niger phytases; however, an homologous region of 33 amino acids was detected. This region of the fungal sequence contains the RHGxRxP consensus motif found in various high molecular mass acid phosphatases and believed to be the acceptor site for phosphate. Expression of the phy S11 cDNA in Escherichia coli allowed the production of the phytase subunit and its assembly to give a protein of the same size as the native phytase. The time course of phy S11 mRNA accumulation during germination showed that no transcript was present in dry seeds. The mRNA accumulated during the first day of germination, to reach a maximum after 2 days (radicle protrusion), and then decreased in young seedlings. Genomic Southern blot analyses suggest the existence of at least two genes and genetic mapping reveals two loci separated by 1 cM on chromosome 3 of maize. The cloning of this first cDNA coding for a plant phytase, will allow the isolation of the corresponding genes and the study of their regulation during germination.
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PMID:Cloning and characterization of a cDNA encoding a maize seedling phytase. 906 71

This experiment was conducted to measure the nutritional and metabolic responses of pigs fed diets with continuous supplementation of microbial and cereal phytase from weaning to finishing, and to determine the feasibility of complete replacement of inorganic P addition by supplemental phytase in swine diets. Forty-eight Landrace x Hampshire x Meishan pigs were divided into four groups. In phase 1 (10 to 50 kg BW), pigs in Groups 1, 2, 3, and 4 were fed a low-P, corn-soybean meal basal diet (BD), the BD plus microbial phytase (A. ficuum) at 1,200 units/kg, the BD plus 10% wheat bran (230 units of cereal phytase/kg), and the BD + .24% inorganic P (calcium phosphate), respectively. In phase 2 (51 to 90 kg BW), these pigs were fed a similar BD or the BD plus 1,000 microbial phytase units/kg, 20% wheat bran, or .20% inorganic P, respectively. Repeated measures included growth performance, P, Ca, and N balance, metatarsal and metacarpal bone strength, serum concentration of inorganic P, Ca, and 1,25-dihydroxycholecalciferol, and serum alkaline phosphatase activity. Pigs fed the BD supplemented with microbial phytase and pigs fed the BD supplemented with inorganic P showed almost identical responses for all variables. Pigs fed the BD supplemented with cereal phytase also had responses for various measures that were similar to those of pigs fed microbial phytase or inorganic P, except for some differences in serum inorganic P concentrations and bone strength in phase 1. Because of improvements in apparent digestibility of dietary P and N, fecal excretion of these two nutrients was reduced by 31 to 62% (P < .05) in pigs fed the BD supplemented with phytase compared with pigs fed inorganic P. It is physiologically feasible and environmentally advantageous to replace inorganic P with microbial or cereal phytase in corn-soybean meal diets for this type of pig through the entire growing-finishing period.
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PMID:Supplemental phytases of microbial and cereal sources improve dietary phytate phosphorus utilization by pigs from weaning through finishing. 911 Feb 15

The finding of heat-stable enzymes or the engineering of moderately thermostable enzymes into more stable ones by random or site-directed mutagenesis has become a main priority of modern biotechnology. We report here for the first time a heat-stable phytase able to withstand temperatures up to 100 degrees C over a period of 20 min, with a loss of only 10% of the initial enzymatic activity. The gene (phyA) encoding this heat-stable enzyme has been cloned from Aspergillus fumigatus and overexpressed in Aspergillus niger. The enzyme showed high activity with 4-nitrophenyl phosphate at a pH range of 3 to 5 and with phytic acid at a pH range of 2.5 to 7.5.
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PMID:Gene cloning, purification, and characterization of a heat-stable phytase from the fungus Aspergillus fumigatus. 914 4

The efficacy of a recombinantly derived microbial phytase (Natuphos 5000, BASF Corp.) was evaluated in sorghum-soybean meal-based diets of finishing swine. During the 50- to 80- and 80- to 118-kg BW intervals, diets contained .40 and .39% plant P, respectively; control diets fed during the two weight intervals were supplemented with .08 and .04% inorganic P from dicalcium phosphate. The all plant-P diets were supplemented with 0, 300, or 500 phytase units (FTU) per kilogram of diet. Supplemental P (P = .09) and phytase (linear, P = .01) increased growth rate but did not affect feed efficiency. Dietary treatment did not affect quantitative carcass traits, CP, fat, or moisture content of the loin or taste panel scores of the cooked loin other than a quadratic decrease (P = .02) in connective tissue amount as phytase supplementation increased. Apparent ileal and total tract digestibilities of DM, GE, and N were not affected (P > .25) by phytase supplementation, whereas ileal and total tract digestibilities of Ca and P increased (P < .05 or P < .01) with increasing phytase supplementation. Ultimate load and ash content of the third and fourth metacarpals and metatarsals and serum P levels increased in response to inorganic P and phytase supplementation. Pig performance, carcass traits, and bone traits were essentially equal for the 300 and 500 FTU/kg treatments. These results show that phytase effectively liberates P in sorghum-based diets, and that 300 FTU/kg (or less) will optimize performance and carcass merit of finishing swine.
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PMID:Efficacy of Natuphos in sorghum-based diets of finishing swine. 915 77

Soil bacteria that utilize inositol hexaphosphate (IHP) were isolated from a range of soils using defined selection media. An analysis of 200 randomly selected isolates indicated that less than 0.5% of the culturable population of soil bacteria were capable of using IHP as a sole source of C and P. From a further 238 isolates obtained from enrichment culture, four unique organisms (identified by randomly amplified polymorphic DNA-polymerase chain reaction) were selected and characterized for their ability to specifically utilize IHP. These four organisms were putatively identified as either fluorescent Pseudomonas spp. (P. putida CCAR53 and CCAR59) or nonfluorescent Pseudomonas spp. (P. mendocina CCAR31 and CCAR60) as determined by partial DNA sequence analysis of 16S rRNA genes. The fluorescent Pseudomonas strains exhibited marked phytase activity and liberated up to 81% of the phosphate from IHP either in the absence or presence of arabinose as an additional C source. The nonfluorescent strains also exhibited an ability to liberate Pi from IHP but were effective only in the presence of added arabinose. Strains CCAR59 and CCAR60 could effectively utilize either Na-IHP or Ca-IHP at pH 7.0, whereas only strain CCAR59 could grow and utilize these substrates at pH 5.0.
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PMID:Soil isolates of Pseudomonas spp. that utilize inositol phosphates. 922 70

Ninety-six (Finnish Landrace x Dutch Landrace) reproductive sows were used at parities 1, 3, 5, and 7 + 8 from d 107 of gestation to d 21 of lactation to investigate the effects of diet and parity on apparent total tract digestibility (ATTD). Animals were randomly assigned to one of four dietary treatments. Dietary treatments were 1) a P-deficient (1.1 g digestible P [dP]/kg) Dutch semipractical diet; 2) Diet 1 supplemented with 400 FTU Aspergillus niger phytase per kilogram of diet (1.7 g dP/kg); 3) a corn-soybean meal-based diet (1.3 g dP/kg); and 4) Diet 3 supplemented with extra monocalcium phosphate (MCP; 2.4 g dP/kg of diet). Animals were fed twice daily at 2.8 times maintenance (418 kJ ME/ BW75) from d 8 to the end of lactation. Feces and urine were collected during d 11 to 13 and d 18 to 20 of lactation. The ATTD of DM, OM, ash, CP, Ca, Mg, and total P (P < .01) were higher for the corn-soybean meal-based diets than for the Dutch semipractical diet not supplemented with phytase. Addition of MCP enhanced total P ATTD by an average of 6.7 percentage units. Addition of microbial phytase improved Ca, Mg, and total P ATTD, but the effects were dependent on the stage of lactation. Lower ATTD of OM and CP were seen for first parity animals compared with higher parity sows. The ATTD of Mg increased with increasing parity. Parity had little effect on the ATTD of minerals during lactation, and dietary effects were prominent and followed a similar trend to those seen in growing-finishing pigs.
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PMID:The effects of sow parity on digestibility of proximate components and minerals during lactation as influenced by diet and microbial phytase supplementation. 926 62


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