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)

Six barrows of approximately 37 kg BW, fitted with two simple T-cannulas in the duodenum (25 cm posterior to the pylorus) and terminal ileum (12 to 15 cm anterior to the ileocecal junction), were fed two diets containing 2.1 g of P/kg in the form of phytic acid and a low intrinsic phytase activity (corn-soybean meal based diet [Diet A] or a typical Dutch diet [Diet B]) without or with supplementary microbial phytase from Aspergillus niger (var. ficuum) equal to 1,500 phytase units per kilogram of diet, in a crossover design. The apparent duodenal, ileal, and total tract (overall) digestibilities of DM, total P, and phytate P (phytic acid x .282) were calculated using both Cr-NDR (neutral detergent residue mordanted with Cr) and Co-EDTA as dual-phase markers. Concentration of total P in the ileal digesta (P less than .01) and feces (P less than .001) of pigs fed microbial phytase was lower than without this enzyme, irrespective of the diet. Ileal digestibility of total P was 18.5 and 29.8 percentage units higher (which was a 1.7- to 2.9-fold increase) due to added Aspergillus niger phytase (P less than .05). Also, total tract (overall) digestibility increased by 27.0 to 29.7 percentage units (P less than .01). Phytic acid concentration in the duodenal and ileal digesta of pigs receiving microbial phytase was lower (P less than .01 or .001), resulting in its higher ileal digestibility (dephosphorylation rate) by 50.1 percentage units for Diet A and by 75.4 percentage units for Diet B. Irrespective of the treatment, no phytase activity could be detected in the ileal digesta of pigs.
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PMID:The effect of supplementary Aspergillus niger phytase in diets for pigs on concentration and apparent digestibility of dry matter, total phosphorus, and phytic acid in different sections of the alimentary tract. 131 45

The Bacillus subtilis strain VTT E-68013 was chosen for purification and characterization of its excreted phytase. Purified enzyme had maximal phytase activity at pH 7 and 55 degrees C. Isolated enzyme required calcium for its activity and/or stability and was readily inhibited by EDTA. The enzyme proved to be highly specific since, of the substrates tested, only phytate, ADP, and ATP were hydrolyzed (100, 75, and 50% of the relative activity, respectively). The phytase gene (phyC) was cloned from the B. subtilis VTT E-68013 genomic library. The deduced amino acid sequence (383 residues) showed no homology to the sequences of other phytases nor to those of any known phosphatases. PhyC did not have the conserved RHGXRXP sequence found in the active site of known phytases, and therefore PhyC appears not to be a member of the phytase subfamily of histidine acid phosphatases but a novel enzyme having phytase activity. Due to its pH profile and optimum, it could be an interesting candidate for feed applications.
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PMID:Isolation, characterization, molecular gene cloning, and sequencing of a novel phytase from Bacillus subtilis. 960 17

The metal ion requirement of a Bacillus subtilis phytase has been studied. Removal of metal ions from the enzyme by EDTA resulted in complete inactivation. Circular dichroism spectroscopy was used to study the effect of metal ion removal on the protein conformation. The loss of enzymatic activity is most likely due to a conformational change, as the circular dichroism spectra of holoenzyme and metal-depleted enzyme were different. Metal-depleted enzyme was partially able to restore the active conformation when incubated in the presence of calcium. Only minor reactivation was detected with other divalent metal ions and their combinations. Based on the data we conclude that B. subtilis phytase requires calcium for active conformation. Calcium has also a strong stabilizing effect on the enzyme against thermal denaturation. However, the conformational change resulted by calcium depletion does not affect the protease susceptibility.
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PMID:The metal dependence of Bacillus subtilis phytase. 1067 9

Marginal zinc deficiency and suboptimal zinc status have been recognized in many groups of the population in both less developed and industrialized countries. Although the cause in some cases may be inadequate dietary intake of zinc, inhibitors of zinc absorption are most likely the most common causative factor. Phytate, which is present in staple foods like cereals, corn and rice, has a strong negative effect on zinc absorption from composite meals. Inositol hexaphosphates and pentaphosphates are the phytate forms that exert these negative effects, whereas the lower phosphates have no or little effect on zinc absorption. The removal or reduction of phytate by enzyme (phytase) treatment, precipitation methods, germination, fermentation or plant breeding/genetic engineering markedly improves zinc absorption. Iron can have a negative effect on zinc absorption, if given together in a supplement, whereas no effect is observed when the same amounts are present in a meal as fortificants. Cadmium, which is increasing in the environment, also inhibits zinc absorption. The amount of protein in a meal has a positive effect on zinc absorption, but individual proteins may act differently; e.g., casein has a modest inhibitory effect of zinc absorption compared with other protein sources. Amino acids, such as histidine and methionine, and other low-molecular-weight ions, such as EDTA and organic acids (e.g., citrate), are known to have a positive effect on zinc absorption and have been used for zinc supplements. Knowledge about dietary factors that inhibit zinc absorption and about ways to overcome or remove these factors is essential when designing strategies to improve the zinc nutrition of vulnerable groups.
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PMID:Dietary factors influencing zinc absorption. 1080 47

Eighty-three isolates from different soil samples exhibited the potential for producing active extracellular phytase. The most active fungal isolate with phytase activity was identified as Penicillium simplicissimum. In shaking culture with enrichment medium, the highest extracellular phytase activity of the producing strain was 3.8 U/mL. The crude enzyme filtrate was purified to homogeneity using ultrafiltration. IEC and gel filtration chromatography. The molar mass of the purified enzyme was estimated to be 65 kDa on SDS-PAGE. The saccharide identification with periodic acid-Schiff reagent (PAS) and activity recognition by 1-naphthyl phosphate was all positive. The isoelectric point of the enzyme, as deduced by isoelectric focusing, was pH 5.8, the optimum pH and temperature being pH 4.0 and 55 degrees C, respectively. The purified enzyme revealed broad substrate specificity and was strongly inhibited by Fe2+, Fe3+ and Zn2+; however, no inhibition was found by EDTA and PMSF. Phytase activity was inhibited when 2 mmol/L of dodecasodium phytate was added and the Km for it was determined to be 813 mmol/L.
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PMID:Isolation and characterization of a novel phytase from Penicillium simplicissimum. 1127 18

Bacillus species producing a thermostable phytase was isolated from soil, boiled rice, and mezu (Korean traditinal koji). The activity of phytase increased markedly at the late stationary phase. An extracellular phytase from Bacillus sp. KHU-10 was purified to homogeneity by acetone precipitation and DEAE-Sepharose and phenyl-Sepharose column chromatographies. Its molecular weight was estimated to be 46 kDa on gel filtration and 44 kDa on SDS-polyacrylamide gel elctrophoresis. Its optimum pH and temperature for phytase activity were pH 6.5-8.5 and 40 degrees C without 10 mM CaCl2 and pH 6.0-9.5 and 60 degrees C with 10 mM CaCl2. About 50% of its original activity remained after incubation at 80 degrees C or 10 min in the presence of 10 mM CaCl2. The enzyme activity was fairly stable from pH 6.5 to 10.0. The enzyme had an isoelectric point of 6.8. As for substrate specificity, it was very specific for sodium phytate and showed no activity on other phosphate esters. The Km value for sodium phytate was 50 microM. Its activity was inhibited by EDTA and metal ions such as Ba2+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, and Mn2+ ions.
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PMID:Purification and properties of extracellular phytase from Bacillus sp. KHU-10. 1159 62

Phosphatase activities associated with the intestinal brush border membrane (BBM) of the rat were examined histochemically in relation to the characteristic environment of the intestine, where luminal pH fluctuates drastically between alkaline and acid pH ranges. Special attention was given to intestinal alkaline phosphatase (IALP) and phytase on the BBM. Whole body fresh-frozen sections of young rats and their rapidly frozen and freeze-substituted small intestines, embedded in Technovit 7100, were processed for the histochemical demonstration of phosphatase activity at three different pH values (9.2, 7.3, and 5.2), representing the deviation of luminal pH in vivo. Either an azo-dye method or lead-salt method was employed using naphthol AS-MX phosphate and ATP as substrate, respectively. With the azo-dye method, intense phosphatase reactions were demonstrated along the BBM at all three pH ranges. Phosphatase reactions of the BBM at pH 9.2 and 7.3 were abolished by L(+)-phenylalanine, heat pre-treatment, and EDTA chelation although some reaction remained at pH 7.3 after the treatment with EDTA or L(+)-phenylalanine. Phosphatase reactions of the BBM at pH 5.2 were resistant to L(+)-phenylalanine, L(+)-tartrate, PCMB and EDTA chelation, implying that the characteristics of the enzyme responsible for phosphohydrolysis at acid pH values differed from those at higher pH values. The lead-salt method in which ATP was used as substrate revealed intense reactions--which were dependent on Mg++ and stimulated by Ca++ and resistant to L(+)phenylalanine--to be localized along the BBM at alkaline and neutral pH values, but not at acid pH values. In vitro experiments showed progressive hydrolysis of naphthol AS-MX phosphate by purified phytase at pH 5.2, in a dose-dependent manner, and suggested the possible involvement of phytase in the phosphatase reactions of the BBM at acid pH. These data indicate that the phosphatase reactions at alkaline and neutral pH values, associated with the BBM of the rat intestine, represent IALP and Mg++/ Ca++-ATPase, while those at acid pH appear to correspond to phytase activity, something which has not been demonstrated by histochemical methods despite the availability of extensive data based on biochemical analyses.
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PMID:Phosphatase activities of rat intestinal enterocytes and their relation to diverse luminal pH, with special references to the possible localization of phytase along the brush border membrane. 1183 8

A recombinant fungal phytase was produced by cultures of sesame hairy roots transformed with Agrobacterium rhizogenes, purified and its molecular properties were characterized. Its transcription level and the phytase production were rapidly increased after 4 weeks of the cultures, suggesting that its transcription and protein synthesis might concur. Western blot analysis provided evidence that the recombinant fungal phytase was secreted into the liquid culture medium of the hairy roots. The phytase enzyme secreted was purified by three steps of ultrafiltration, DEAE-Sepharose ion exchange chromatography, and Sephadex G-100 size-exclusion chromatography. As a result, one single band signal was observed with SDS-PAGE, indicating that the purification step was reasonable. The positive signs of both the zymogram and the PAS staining on SDS-PAGE suggested that the activity of the final product phytase was active and glycosylated. The optimal reaction temperature of the phytase was between 50 and 60 degrees C and at over 60 degrees C its activity was reduced by 30-90%, depending on the temperatures applied. Pre-incubation at temperatures of 20-50 degrees C showed stable catalytic activity, while at over 50 degrees C the phytase activity was gradually decreased by 90%. The optimal pH was between 4 and 5 pH values for the recombinant fungal phytase, while for native phytase it was at pH 5.0. Addition of iron ion inhibited the phytase activity but treatments of some cations, EDTA, and PMSF showed no effect on the activity or slightly stimulated it positively.
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PMID:Expression and characterization of extracellular fungal phytase in transformed sesame hairy root cultures. 1535 75

Including low-phytic-acid grains in swine diets can reduce P concentrations in manure, but the influence on manure P composition is relatively unknown. To address this we analyzed manure from swine fed one of four barley (Hordeum vulgare L.) varieties. The barley types consisted of wild-type barley (CDC bold, normal barley diet) and three low-phytic-acid mutant barleys that contained similar amounts of total P but less phytic acid. The phytic acid concentrations in the mutant barleys were reduced by 32% (M422), 59% (M635), and 97% (M955) compared with that in the wild-type barley, respectively. Phosphorus concentrations were approximately one-third less in manures from animals fed low-phytic-acid barleys compared with those fed the wild-type variety. Phytic acid constituted up to 55% of the P in feed, but only trace concentrations were detected in NaOH-EDTA extracts of all manures by solution (31)P nuclear magnetic resonance (NMR) spectroscopy. Phosphate was the major P fraction in the manures (86-94% extracted P), with small concentrations of pyrophosphate and simple phosphate monoesters also present. The latter originated mainly from the hydrolysis of phospholipids during extraction and analysis. These results suggest that phytic acid is hydrolyzed in swine, possibly in the hind gut by intestinal microflora before being excreted in feces, even though the animals have little phytase activity in the gut and derive little nutritional benefit from phytate P. We conclude that feeding low-phytic-acid grains reduces total manure P concentrations and the manure P is no more soluble than P generated from normal barley diets.
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PMID:Phosphorus composition of manure from swine fed low-phytate grains: evidence for hydrolysis in the animal. 1553 62

A gene, phoI, coding for a phosphatase from Enterobacter sp. 4 was cloned in Escherichia coli and sequenced. Analysis of the sequence revealed one open reading frame (ORF) that encodes a 269-amino acid protein with a calculated molecular mass of 29 kDa. PhoI belongs to family B acid phosphatase and exhibits 49.4% identity and 62.4% homology to the hel gene from Heamophilus influenzae, which encoded an outer membrane protein (P4). The optimum pH and temperature for phosphatase activity were pH 5.5 and 40 degrees C, respectively. Its specific activity on rho-nitrophenyl phosphatate was 70 U/mg at pH 5.5 and 40 degrees C. Enzyme activity was inhibited by Al3+, EDTA, and DTT, but fivefold activated by Cu2+ ion (350 U/mg). PhoI showed a strong synergistic effect when used with a purified E. coli phytase, AppA, to estimate combination effects.
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PMID:Cloning, sequencing and characterization of a novel phosphatase gene, phoI, from soil bacterium Enterobacter sp. 4. 1655 Apr 60


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