Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.8 (phytase)
 1,997 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Soaking of a rat diet, high in both plant phytate and phytase, progressively degraded the phytate content with time of soaking. This dephytinization in turn enhanced the digestion of feed organic matter in the animals, and it significantly improved the absorption and retention of minerals and trace elements as observed in balance studies. Incorporation of elements into specific tissues was evaluated as a reflection of bioavailability. Some tissues did reflect the preceding absorption of certain elements; other tissues seemed less suitable as indicators of trace element absorption. Dietary calcium addition in many ways contrasted the soaking procedure: inorganic calcium addition to the feed reduced phosphorus, magnesium, and trace element bioavailability, and interfered with the internal deposition of the elements. The external dephytinization of the feed did not affect the phosphohydrolase activity of the intestinal mucosa as manifested by alkaline phosphatase activity or phytase activity. The mucosal phytase and alkaline phosphatase activities were, however, mutually correlated, supporting the view that "phytase" activity is a less substrate-specific action of alkaline phosphatase activity or a fraction of this activity.
 ...
PMID:Dephytinization of a rat diet. Consequences for mineral and trace element absorption. 750

1. Three experiments were carried out to determine the phosphorus (P) requirements of laying hens aged 34 to 58 weeks (experiment 1), 59 to 70 weeks (experiment 2) and 22 to 50 weeks (experiment 3) given diets containing wheat, sorghum and soyabean meals as the main ingredients. Dietary total P (Pt) varied between 3.2 and 7.3 g/kg (experiment 1), 3.2 and 4.6 g/kg (experiment 2) and 3.0 and 6.6 g/kg (experiment 3). Hens were housed at either 18 degrees or 30 degrees C (experiments 1 and 2) and uncontrolled temperature (experiment 3), and in experiment 2 diets were fed without or with a phytase supplement of 500 units/g. 2. Dietary Pt had no significant effect on production measures in any experiment. Increases in dietary Pt adversely influenced egg shell quality although uterine calcium (Ca), ATPase and carbonic anhydrase activities were unaffected. 3. A 3-d-feeding trial in experiment 1 gave maximum Pt retentions of 228 mg/d at 18 degrees C and 204 mg/d at 30 degrees C. These were obtained with diets containing, respectively, 4.6 and 6.0 g Pt/kg. 4. Plasma inorganic P (Pi) increased consistently with increases in dietary Pt at all temperatures but plasma total Ca, and tibia Ca and P, were unaffected. 5. The inclusion of the phytase supplement in diets containing 3.2 and 4.6 g Pt/kg had an adverse effect on egg production at both temperatures in experiment 2. 6. A dietary Pt concentration of 3.2 g/kg, providing a calculated 1.2 g available P (Pav)/kg, with a dietary phytase activity of less than 200 units/kg, satisfied the P requirements of the hens used in these studies. However, the data from experiment 3 suggest that the Pt requirement of some flocks fed on wheat-based diets may be lower than 3.2 g/kg.
 ...
PMID:Phosphorus requirements of laying hens fed on wheat-based diets. 765 2

Phytases are the primary enzymes responsible for the hydrolysis of phytic acid, myo-inositol-1,2,3,4,5,6-hexakisphosphate (I-1,2,3,4,5,6-P6). A number of phytases with varying specificities, properties, and localizations hydrolyze phytic acid present in cells. The specificity of hydrolysis of phytic acid by alkaline phytase from lily (Lilium longiflorum L.) pollen is described. Structures of the intermediate inositol phosphates and the final product were established by a variety of nuclear magnetic resonance techniques (1H-, 31P-, and 31P-1H-detected multiple quantum coherence spectroscopy, and total correlation spectroscopy). On the basis of the structures identified we have proposed a scheme of hydrolysis of phytic acid. Initial hydrolysis of the phosphate ester occurs at the D-5 position of phytic acid to yield the symmetrical I-1,2,3,4,6-P5. The two subsequent dephosphorylations occur adjacent to the D-5 hydroxyl group to yield I-1,2,3-P3 as the final product. Alkaline phytase differs from other phytases in the specificity of hydrolysis of phosphate esters on the inositol ring, its high substrate specificity for phytic acid, and biochemical properties such as susceptibility to activation by calcium and inhibition by fluoride. The physiological significance of alkaline phytase and the biological role of I-1,2,3-P3 remain to be identified.
 ...
PMID:Specificity of hydrolysis of phytic acid by alkaline phytase from lily pollen. 784 60

The effect of the addition of microbial phytase to a diet based on field beans (30%), wheat (28%), peas (25%), and barley (14%) was studied in a 2-week experiment with 3 x 8 castrated male, individually housed, hybrid piglets (live weight range 12-16 kg). All diets contained about 4.7 g Ca, 4.2 g P (77% present as phytate phosphorus), 1.0 g Mg, 60 mg Zn per kg diet, and 17% crude protein. Group I was fed the basal diet with a native phytase-activity of about 260 U per kg diet. In group II, 350 U, in group III, 700 U of microbial phytase per kg diet were added. The addition of microbial phytase improved the apparent P absorption (% of intake) from 48% (group I) to 66% (group II) and 71% (group III). Comparable positive effects from the phytase treatment were obtained for the calcium utilization. The phytase supplementation also enhanced plasma zinc concentration significantly. The concentration of inorganic phosphorus in plasma, the zinc digestibility, and the magnesium balance were improved in tendency. The utilization of nitrogen remained unchanged.
 ...
PMID:Dietary effect of phytogenic phytase and an addition of microbial phytase to a diet based on field beans, wheat, peas and barley on the utilization of phosphorus, calcium, magnesium, zinc and protein in piglets. 807 7

Mobilization of Ca2+ from microsomal/vacuolar fractions was detected when InsP6-phytase was added after a definite time of hydrolysis which coincides with the time (20-30 min) of optimal production of Ins(2,4,5)P3 bound to phytase. The in vitro constituted Ins(1,4,5)P3 or Ins(2,4,5)P3-phytase complex is also effective in releasing Ca2+. InsP3-phytase complex releases 45% more microsomal Ca2+ than that released by free InsP3 under identical conditions. Other inositol-phytase complexes are ineffective. Furthermore InsP3-phytase complex is recognised by putative receptor associated with microsomal fraction suggesting that the myoinositol tris-phosphate-phytase complex can act as an elicitor in Ca2+ mobilization in plant systems where phytate and phytase occur.
 ...
PMID:Myoinositol tris-phosphate-phytase complex as an elicitor in calcium mobilization in plants. 838 39

These studies were conducted to determine if supplementation of a corn-soybean meal diet with 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] would increase the utilization of natural phytate phosphorus by broiler chickens. Two experiments were conducted to evaluate the effect of dietary 1,25-(OH)2D3 in the presence and absence of supplemental phytase and at several dietary levels of inorganic phosphorus supplementation. The criteria measured in these studies were weight gain, gain:feed ratio, bone ash, rickets due to phosphorus deficiency, plasma calcium and phosphorus and retention of calcium, phosphorus and phytate phosphorus. In the first experiment, the types and amounts of fecal inositol phosphates were determined by HPLC, and the total fecal phytate was determined by the classic FeCl3 precipitation technique. In the first experiment, the addition of 1,25-(OH)2D3 to the diet in the presence of dietary phytase resulted in greater 9-d weight and bone ash and lower incidence of rickets; the retention of total fecal phytate and phytate phosphorus was greater than in controls. The second experiment was a complete 2 x 2 x 2 factorial design [phosphorus levels x phytase x 1,25-(OH)2D3]. The addition of 1,25-(OH)2D3 alone to the diet resulted in greater 9-d weight and bone ash, lower incidence of rickets, and greater retention of total calcium and phosphorus and phytate phosphorus. The highest retention of phytate phosphorus (79.4%) was obtained when both phytase and 1,25-(OH)2D3 were present in the diet. The possible mode of action and importance of these results in many areas of nutrition and environmental science are discussed.
 ...
PMID:Dietary 1,25-dihydroxycholecalciferol supplementation increases natural phytate phosphorus utilization in chickens. 838 10

Two experiments were conducted to determine the effects of supplemental microbial phytase on utilization of dietary zinc by weanling pigs. Experiment 1 was a 2 x 3 factorial arrangement of treatments with 24 pigs for 4 wk. Two levels of phytase activity (0 and 1350 units/g) and three levels of zinc (0, 30 and 60 mg/kg as ZnSO4.7H2O) were added to a corn-soybean meal basal diet. Weekly measures included growth performance, plasma alkaline phosphatase activity and plasma mineral concentrations. In Experiment 2, mineral balances were determined in 12 pigs fed the basal diet or the diet with added zinc (30 mg/kg) or phytase (1350 units/g). The results indicated that either supplemental phytase or supplemental zinc increased plasma alkaline phosphatase activity and plasma zinc concentrations, but these increases were not additive. Supplemental phytase decreased plasma alkaline phosphatase activity in pigs supplemented with zinc. Supplemental phytase also significantly enhanced weight gain, feed intake, gain:feed ratio, plasma concentrations of inorganic phosphorus, and retention of phosphorus and calcium. Neither supplemental phytase nor zinc affected zinc retention. Supplementing corn-soybean meal diets with microbial phytase at 1350 units/g feed improves bioavailability of zinc as well as of phytate phosphorus to weanling pigs.
 ...
PMID:Supplemental microbial phytase improves bioavailability of dietary zinc to weanling pigs. 838

Microbial phytase was added at concentrations of 0, 500, and 1,000 phytase units per gram (PU/g) to a diet that derived the majority of its phosphorus content from organic sources. In addition, a positive control diet was prepared by adding calcium phosphate to increase the total dietary phosphorus by 1.7 g/kg. Each diet was available ad libitum for 3 wk to nine individually penned pigs approximately 5 wk old and with an initial weight of 10.2 kg. Digestibility of phosphorus was estimated, using chromic oxide as an indicator, from fecal samples obtained during the 3rd wk of the trial. Blood serum and metatarsal bones were obtained at slaughter. The addition of the microbial enzyme resulted in increased rate and efficiency of gain, increased digestibility of dietary phosphorus, increased serum phosphorus, decreased serum alkaline phosphatase, and increased metatarsal ash and weight of metatarsal phosphorus. The response to dietary microbial phytase was similar to that resulting from feeding a diet containing 1.7 g/kg of additional phosphorus from calcium phosphate.
 ...
PMID:Addition of microbial phytase to diets of young pigs. 839 74

The degradation of phytate (inositol hexaphosphate) in rapeseed meal diet not containing phytase activity was studied in 15 growing ileum-fistulated pigs. Stomach and small intestinal degradation and total gastrointestinal degradation were compared. The effect of addition of calcium carbonate to the rapeseed meal diet at two levels (9.2 and 18.5 g/kg diet) was investigated. A commercial barley-wheat-soybean diet with intrinsic phytase activity was used as reference. Phytate and its hydrolysis products in diets, ileal digesta and feces were determined by HPLC ion-pair chromatography. Hydrolysis of phytate in the stomach and small intestine was 35-45% in pigs fed the rapeseed meal diet independent of calcium addition, and 65% in pigs fed the reference diet. Total gastrointestinal degradation of phytate in pigs fed the rapeseed diet was 97, 77 and 42% (P < 0.001) when calcium intakes were 4.5, 9.9 and 15 g/d, respectively; total gastrointestinal degradation was 72% in pigs fed the reference diet. The intestinal phytate degradation pattern, when rapeseed diet was fed, indicated the activity of an unspecific phosphatase, whereas that of the reference diet indicated intrinsic dietary phytase activity. We conclude that dietary supplementation of calcium carbonate decreases the phytate degradation in the colon of pigs, but not in the stomach and small intestine.
 ...
PMID:High dietary calcium level decreases colonic phytate degradation in pigs fed a rapeseed diet. 846 57

In an earlier study a mutant Dictyostelium cell-line (plc-) was constructed in which all phospholipase C activity was disrupted and nonfunctional, yet these cells had nearly normal Ins(1,4,5)P3 levels (Drayer, A.L., Van Der Kaay, J., Mayr, G.W, Van Haastert, P.J.M. (1990) EMBO J. 13, 1601-1609). We have now investigated if these cells have a phospholipase C-independent de novo pathway of Ins(1,4,5)P3 synthesis. We found that homogenates of plc- cells produce Ins(1,4,5)P3 from endogenous precursors. The enzyme activities that performed these reactions were located in the particulate cell fraction, whereas the endogenous substrate was soluble and could be degraded by phytase. We tested various potential inositol polyphosphate precursors and found that the most efficient were Ins(1,3,4,5,6)P5, Ins(1,3,4,5)P4, and Ins(1,4,5,6)P4. The utilization of Ins(1,3,4,5,6)P5, which can be formed independently of phospholipase C by direct phosphorylation of inositol (Stephens, L.R. and Irvine, R.F. (1990) Nature 346, 580-582), provides Dictyostelium with an alternative and novel pathway of de novo Ins(1,4,5)P3 synthesis. We further discovered that Ins(1,3,4,5,6)P5 was converted to Ins(1,4,5)P3 via both Ins(1,3,4,5)P4 and Ins(1,4,5,6)P4. In the absence of calcium no Ins(1,4,5)P3 formation could be observed; half-maximal activity was observed at low micromolar calcium concentrations. These reaction steps could also be performed by a single enzyme purified from rat liver, namely, the multiple inositol polyphosphate phosphatase. These data indicate that organisms as diverse as rat and Dictyostelium possess enzyme activities capable of synthesizing the second messengers Ins(1,4,5)P3 and Ins(1,3,4,5)P4 via a novel phospholipase C-independent pathway.
 ...
PMID:A novel, phospholipase C-independent pathway of inositol 1,4,5-trisphosphate formation in Dictyostelium and rat liver. 853 Mar 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>