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)

Undernutrition during the suckling period imposed by maternal protein deficiency during lactation resulted in elevated inositol triphosphatase activity (units per gram of wet tissue) in the ileum and lower phytase activity in the duodenum and jejunum. Activities of inositol triphosphatase in the duodenum and jejunum and phytase in ileum were unaffected. Postweaning nutritional rehabilitation resulted in elevated specific activities of both enzymes in all segments; however, activities of whole segments were similar to the corresponding control values. Elevation of inositol triphosphatase (ileum) and decline of phytase (duodenum and jejunum) activities due to undernutrition were reversed by the administration of hydrocortisone or thyroxine during undernutrition. These results suggest that maturation of activities of inositol triphosphatase in ileum (by hydrocortisone) and phytase in all segments (by both hydrocortisone and thyroxine) is under hormonal regulation, and the effects of neonatal undernutrition may be partly due to hormonal imbalances.
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PMID:Effects of neonatal undernutrition and subsequent nutritional rehabilitation or administration of thyroxine and hydrocortisone on the inositol phosphatase activities in rat intestine. 302 Feb 20

Inositol phosphatase and phytase activities in different segments of the rat small intestine were measured during postnatal development. In the duodenum and jejunum, inositol phosphatase activity (units/g tissue) was low during the suckling period and increased at weaning, reaching a peak of activity at 4 weeks of age. In the ileum, peak activity was observed during the suckling period with a sharp decline at weaning. Phytase activity was very low during the suckling period in all segments, and increased to exhibit a peak at 4 weeks of age in the duodenum, and to a lesser extent in the jejunum (low activity was maintained in the ileum). The content of inositol phosphatase activity in the duodenum increased rapidly during the suckling period to reach its maximum at 4 weeks of age. This suggests a relationship to cell proliferation rate in the small intestinal mucosa.
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PMID:Inositol phosphatase in developing rat duodenum, jejunum and ileum. 302 Dec 46

The cause of marked inhibitory effect of bran on absorption of dietary nonheme iron was studied in man by double-radioiron technique. Washing bran with hydrochloric acid but not with water removed inhibitory factor(s). Inhibition was almost restored by reconstituting phytate level. Removal of phytates in bran by endogenous phytase significantly increased absorption of iron. Removing, by washing with water, phosphates formed from phytates during enzymatic dephytinization led to a bran fraction with only a small remaining inhibitory effect on iron absorption. Half the iron in bran is in the form of monoferric phytate, which is well-absorbed. When potassium and magnesium phytates were added in amounts present in bran, the same inhibitory effect on iron absorption was seen. Although there appear to be other factors in bran that partly explain the inhibition, phytates are the main cause of the inhibitory effect of bran on iron absorption.
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PMID:Phytates and the inhibitory effect of bran on iron absorption in man. 303 44

In contrast to corn, wheat and triticale exhibit high phytase activities. This enzyme enhances phytic phosphorus availability, as demonstrated in pigs given wheat diets. To study the utilization of triticale phosphorus in pigs, the importance of dietary phytase content and the mineral and bone disorders related to high phytate feeding, a nutritional experiment was carried out in 12 growing pigs fed either a corn- or a triticale-based diet for 6 wk. The diets were almost identical except for the cereal component; their phosphorus contents were low (0.4%) and mainly phytic. The following parameters were measured: calcium and phosphorus balances, bone and plasma contents of calcium and phosphorus, plasma vitamin D metabolites and parathyroid hormone (PTH), bone bending moments and intestinal phosphatase activities. Both diets provoked a phosphorus deficiency, but hypophosphatemia occurred less rapidly, hypercalciuria and hypophosphaturia were less marked and phosphorus availability was greater when the triticale diet was fed. This was attributed to the high phytase content of triticale because intestinal phytase and alkaline phosphatase activities were similar in pigs fed either diet. Calcium absorption was not modified by calcium retention was greater for pigs fed triticale and led to higher bone scores. In conclusion, the higher the phytase activity of the diet, the greater the phytate P availability and the lower the bone-mineral disorders.
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PMID:Importance of cereal phytase activity for phytate phosphorus utilization by growing pigs fed diets containing triticale or corn. 303 49

Extracellular phytase from Aspergillus ficuum, a glycoprotein, was purified to homogeneity in 3 column chromatographic steps using ion exchange and chromatofocusing. Results of gel filtration chromatography and SDS-polyacrylamide gel electrophoresis indicated the approximate molecular weight of the native protein to be 85-100-KDa. On the basis of a molecular weight of 85-KDa, the molar extinction coefficient of the enzyme at 280 nm was estimated to be 1.2 X 10(4) M-1 cm-1. The isoelectric point of the enzyme, as deduced by chromatofocusing, was about 4.5. The purified enzyme is remarkably stable at 0 degree C. Thermal inactivation studies have shown that the enzyme retained 40% of its activity after being subjected to 68 degrees C for 10 minutes, and the enzyme exhibited a broad temperature optimum with maximum catalytic activity at 58 degrees C. The Km of the enzyme for phytate and p-nitrophenylphosphate is about 40 uM and 265 uM, respectively, with an estimated turnover number of the enzyme for phytate of 220 per sec. Enzymatic deglycosylation of phytase by Endoglycosidase H lowered the molecular weight of native enzyme from 85-100-KDa to about 76-KDa; the digested phytase still retained some carbohydrate as judged by positive periodic acid-Schiff reagent staining of the electrophoresed protein. Immunoblotting of the phytase with monoclonal antibody 7H10 raised against purified native enzyme recognized not only native but also partially deglycosylated protein.
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PMID:Extracellular phytase (E.C. 3.1.3.8) from Aspergillus ficuum NRRL 3135: purification and characterization. 303 33

Due to its high phytate content, the bioavailability of zinc in whole meal cereal products is distinctly lower as compared to foods of animal origin. The effect of reducing the phytate content of cereal products made from rye and wheat on growth, zinc content of femur and blood serum, as well as on the activity of serum alkaline phosphatase was investigated during a 3-week feeding trial in growing rats. The reduction of phytate was achieved by controlling the phytase activity originally present in cereals. By these treatments, the molar phytic acid/zinc ratio in the cereal products was reduced from 27-37 to 3-18. The four parameters under investigation showed a significant improvement in zinc bioavailability with decreasing phytic acid/zinc ratios. The relevance of these results for man and the value of the molar phytic acid/zinc ratio as an indicator of the bioavailability of zinc in foods are discussed.
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PMID:[Biological availability of zinc in whole grain products with different phytate contents]. 343 24

The role of bacterial, dietary and intestinal phytases (EC 3.1.3.8) in the hydrolysis of phytate was investigated in the golden hamster and rat by assaying phytase in the small intestine and by measuring the disappearance of phytate from the stomach and large intestine, using chromium oxide as an insoluble solid-phase marker. It was confirmed that an active phytase was present in the proximal third of the small intestine of the rat but the enzyme was undetectable in the hamster. Extensive bacterial breakdown of phytate occurred in the pregastric pouch and true stomach of the hamster with both phytase-containing and phytase-free diets, with phytate digestibilities in the true stomach ranging from 0.69-0.90, confirming that the hamster can be regarded as a pseudo-ruminant. With a phytase-free diet, the digestibility of phytate in the stomach of the rat was very low (0.05) but with a wheat-based diet substantial breakdown of phytate occurred (digestibility up to 0.49), presumably under the influence of the cereal phytase. Intestinal phytase did not appear to be of great significance in the rat but some further hydrolysis of the residual phytate probably occurred in the large intestine of both species by bacterial phytase.
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PMID:A comparative study of phytate hydrolysis in the gastrointestinal tract of the golden hamster (Mesocricetus auratus) and the laboratory rat. 406 29

A culture enrichment technique was used to isolate phytase-producing microorganisms. Also, microorganisms from various culture collections were tested for their phytase-producing ability. A number of the Aspergillus niger group produced extracellular phytase which dephosphorylated calcium phytate in acidic solution. A soil isolate, A. ficuum NRRL 3135, produced the most active phytase in a cornstarch-based medium. Production of phytase was strongly repressed by inorganic phosphates and required a high carbon to phosphorus ratio in the medium.
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PMID:Survey of microorganism for the production of extracellular phytase. 430 Jan 71

Two types of extracellular acid phosphatases are synthesized by Aspergillus ficuum NRRL 3135: a nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with an optimum pH of 2.0, and an enzyme with restricted specificity, a mesoinositol-hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with an optimum pH of 5.5. Although the pH 5.5 enzyme is termed a phytase, both enzymes hydrolyze phytin. Synthesis of the enzymes is repressed by high orthophosphate concentrations in the fermentation medium. The highest total level for each enzyme is synthesized in low orthophosphate medium. In high orthophosphate medium, more pH 5.5 enzyme is produced than pH 2.0 enzyme. In low orthophosphate medium, more pH 5.5 enzyme is produced than pH 2.0 enzyme during the early stages of growth, but the reverse occurs after 5 days. The enzymes are differentiated by heat denaturation at acid and alkaline pH levels. They are separated into two distinct fractions on Sephadex G-100 followed by carboxymethylcellulose column chromatography. This indicates that the two enzymes are structurally different. The K(m) for both enzymes is 1.25 mm when calcium phytate is the substrate. Orthophosphate competitively inhibits the pH 2.0 (K(i) = 1.1 x 10(-2)m) but not the pH 5.5 phosphatase. Neither enzyme is denatured by 50% (w/v) urea or inhibited by 0.01 m tartrate. Thus, they differ from human prostatic phosphatase.
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PMID:Regulation of the formation of acid phosphatases by inorganic phosphate in Aspergillus ficuum. 431 67

The fungus Aspergillus ficuum NRRL 3135 is known to produce an extracellular nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with a pH optimum of 2.0, as well as an extracellular myo-inositol hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with pH optima of 2.0 and 5.5. Both these enzymes are also known to hydrolyze myo-inositol hexaphosphate. The pentaphosphates liberated in the first step of this hydrolysis have been isolated and identified by ion-exchange chromatography and optical rotation. The nonspecific orthophosphoric monoester phosphohydrolase produces a single pentaphosphate, d-myo-inositol-1,2,4,5,6-pentaphosphate, whereas the phytase, at both pH 2.0 and 5.5, produces a mixture of two pentaphosphates. The major component of this mixture is d-myo-inositol-1,2,4,5,6-pentaphosphate and the other is d-myo-inositol-1,2,3,4,5-pentaphosphate. Thus the pathways of dephosphorylation of myo-inositol hexaphosphate by these two enzymes differ from that of wheat-bran phytase which forms l-myo-inositol-1,2,3,4,5-pentaphosphate.
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PMID:Inositol phosphate phosphatases of microbiological origin: the inositol pentaphosphate products of Aspergillus ficuum phytases. 434 16


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