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)

Techniques have been developed to produce microbial phytase for addition to diets for simple-stomached animals, with the aim to improve phosphorus availability from phytate-P in plant sources. The activity of the crude microbial phytase showed pH optima at pH 5.5 and 2.5. The enzyme was able to degrade phytate in vitro in soya-bean meal, maize and a liquid compound feed for pigs. When microbial phytase was added to low-P diets for broilers the availability of P increased to over 60% and the amount of P in the droppings decreased by 50%. The growth rate and feed conversion ratio on the low-P diets containing microbial phytase were comparable to or even better than those obtained on control diets. Addition of microbial phytase to diets for growing pigs increased the apparent absorbability of P by 24%. The amount of P in the faeces was 35% lower.
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PMID:Improvement of phosphorus availability by microbial phytase in broilers and pigs. 1570 36

Aspergillus carneus (Van Tiegh) Blockwitz synthesized moderate quantities of phytase in culture filtrate. Maximal enzyme yield was obtained after eight days incubation statically in a medium containing sucrose and K2HPO4 in a C/P ratio of 591.8/1 with 0.1% corn steep liquor (CSL) as the sole source of nitrogen. Substitution of (NH4)2SO4 with certain amino acids decreased phytase yields significantly. Addition of fish or soybean meal to the nitrogen-free medium failed to enhance phytase production. The enzyme was purified about 43-fold from the culture filtrate by precipitation with acetone, gel filtration through Sephadex G-75 and ion exchange chromatography on DEAE-cellulose. Activity of both crude and purified phytase was influenced greatly by changing of pH and reaction temperature: maximum activity of the crude enzyme occurred at 35 degrees C and pH 5.6, whereas that of the purified preparation at 40 degrees C and pH 5.6. The pure enzyme was found stable between pH 5.6-6.2. About 68% of the enzyme activity was lost by heating at 45 degrees C for 60 min. The pure phytase retained its activity over a long period when stored at 4 degrees C.
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PMID:Biosynthesis, purification and some properties of extracellular phytase from Aspergillus carneus. 217 69

Inositol compounds with three to five phosphate groups (IP3-IP5) were produced by hydrolysis of phytate (inositol hexaphosphate, IP6) and their binding affinities for calcium and zinc investigated at neutral pH with relative concentrations that had been found in a range of students' meals. Zn solubility was negligible at many of these concentrations, with less Zn bound to precipitates of Ca-IP6 than Ca-IP5. The capacity to precipitate Zn at these ratios fell between IP5 and IP3. Zn was partially desorbed by soluble chelators (histidine and picolinate), especially when it had been adsorbed to preformed Ca-IP precipitates. A lower proportion of Zn was accessible to soluble chelators from Ca-IP4 than the other compounds. IP3-IP4 were hydrolysed by phytase more readily than IP5-IP6.
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PMID:Binding of zinc and calcium to inositol phosphates (phytate) in vitro. 240 Jul 62

Human intestinal phytases play a minor role in phytate degradation. However, endogenous phytases in bran have a major effect on phytate hydrolysis. The amount of endogenous phytase activity varies with the method of processing of the fiber.
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PMID:Phytase and phytate degradation in humans. 254 85

A sugar phosphomonoester, myo-inositol hexakisphosphate (phytic acid), has been identified as a major phosphorylated metabolite in Dictyostelium discoideum amoeba. Its intracellular concentration was estimated to be 0.7 mM. The identification was made in perchloric acid extracts on the basis of 31P-NMR chemical shift values and their variations with pH, by addition of authentic compound and by hydrolysis with wheat phytase. Perchloric acid extracts were prepared so as to avoid losses of insoluble salts of polyphosphorylated compounds with divalent cations. The glycolytic intermediate, 3-phosphoglycerate accumulated intracellularly in amoebae incubated in the presence of fluoride. The pH sensitive NMR signal of 3-phosphoglycerate was used to monitor cytosolic pH and a value of pH 7.4 was found in aerobic Dictyostelium amoebae.
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PMID:Identification of inositol hexaphosphate in 31P-NMR spectra of Dictyostelium discoideum amoebae. Relevance to intracellular pH determination. 282 May 8

1. The effect of extrusion cooking of a high-fibre cereal product on digestibility of starch, fibre components and phytate in the stomach and small intestine was studied by in vivo digestion in ileostomy subjects, as well as its effect on ileostomy losses of fat, nitrogen, sodium and potassium. 2. Seven ileostomy subjects were studied during two periods (each of 4 d) while on a constant low-fibre diet supplemented with 54 g/d of a bran-gluten-starch mixture (period A) or the corresponding extruded product (period B). 3. Extrusion cooking, using mild conditions, did not change the content of starch, dietary fibre components or phytate of the bran product, but the phytase (EC 3.1.3.26) activity was lost. During the period using the extruded bran product, there was a significant increase in recovery of phytate-phosphorus (period A, 44% of intake; period B, 73% of intake). The amount of fibre components, fat, fatty acids, N, Na, K, water and the ash weight of the ileostomy contents did not differ between the two periods. Only 0.6 and 0.7% respectively of ingested starch was recovered in ileostomy contents in periods A and B, while the fibre components were almost completely recovered. 4. Extrusion cooking, using even mild conditions, may lead to a considerable impairment in the digestion of phytate, probably due to a qualitative change in phytate and a loss of phytase activity. Starch, before and after extrusion cooking, is almost completely digested in the stomach and small intestine while fibre components are digested to a very small extent.
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PMID:Extrusion cooking of a high-fibre cereal product. 1. Effects on digestibility and absorption of protein, fat, starch, dietary fibre and phytate in the small intestine. 282 63

To investigate the digestion of phytate in the stomach and small intestine in humans, studies were performed in subjects with established ileostomy. A recently developed high performance liquid chromatography method made it possible to analyze phytate and its degradation products in food and digesta. The digestibility of phytate in raw bran and extruded bran was investigated in seven ileostomy patients. Each subject was studied for two 4-d periods while consuming a constant low fiber diet with the addition of either 54 g/d of a bran-gluten-starch mixture or the corresponding extruded product. During passage through the subject's stomach and small intestine 58%, on average, of the phytate in unprocessed bran was hydrolyzed to inositol penta-, tetra- and triphosphates. When bran was subjected to extrusion cooking, 25% of the inositol hexaphosphate was hydrolyzed to penta- and tetraphosphate and the phytase activity ceased. Essentially no phytate digestion occurred when the ileostomy subjects consumed the extruded product. The reduced digestibility might be due to the lost phytase activity or to formation of indigestible phytate complexes during extrusion cooking.
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PMID:Degradation products of bran phytate formed during digestion in the human small intestine: effect of extrusion cooking on digestibility. 282 27

Soybean phytase (myo-inositol-hexakisphosphate phosphohydrolase; EC 3.1.3.8) was purified from 10-day-old germinating cotyledons using a four-step purification scheme. Phytase was separable from the major acid phosphatase present, and stained as a minor band of the three acid phosphatases detectable by activity staining after gel electrophoresis. The purified enzyme exhibited two closely migrating bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of approximately 59 and 60 KDa. The molar extinction coefficient of the enzyme at 280 nm was estimated to be 7.5 X 10(4) M-1 cm-1. The isoelectric point of phytase, as judged by the elution profile on chromatofocusing, was about 5.5. The enzyme was totally absorbed to a Procion Red HE3B column and eluted as a single protein component at a salt concentration of 250-300 mM. The enzyme possessed a high affinity for phytic acid (apparent Km = 48 microM), and was strongly inhibited by phosphate (apparent Ki = 18 microM), vanadate, and fluoride. Characteristic of other plant phytases, the pH and temperature optima were 4.5-4.8 and 55 degrees C, respectively.
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PMID:Purification and characterization of phytase from cotyledons of germinating soybean seeds. 282 33

Soybean acid phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.2) was completely separated from phytase (EC 3.1.3.8) isolated from cotyledons of germinating seeds and purified to homogeneity. A four-step purification regimen consisting of ammonium sulfate fractionation, and ion-exchange, affinity, and chromatofocusing gel chromatographies was employed to achieve a homogeneous preparation. Acid phosphatase activity appeared as a major band of the three forms of acid phosphatase identified on native gels. The purified enzyme had a molecular weight of 53,000 when electrophoresed on 8% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a molecular weight of 53,000 from its mobility in a Fracto-gel TSK HW-50F gel permeation column. The molar extinction coefficient of the enzyme at 278 nm was estimated to be 4.2 X 10(4) M-1 cm-1. The isoelectric point of the protein, as revealed by chromatofocusing, was about 6.7. The optimal pH for activity, like other plant acid phosphatases, was 5.0. While the enzyme failed to accommodate phytate as a substrate, the enzyme did exhibit a broad substrate selectivity. The affinity of the enzyme for p-nitrophenyl phosphate was high (Km = 70 microM), and activity was competitively inhibited by orthophosphate (Ki = 280 microM). The estimated catalytic turnover number (Kcat) of the enzyme for p-nitrophenyl phosphate was about 430 per second. Although the purified enzyme was stable at 0 degrees C and exhibited maximum catalytic activity at 60 degrees C, thermal inactivation studies indicated that the enzyme lost 100% activity after treatment at 68 degrees C for 10 min.
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PMID:Purification and characterization of acid phosphatase from cotyledons of germinating soybean seeds. 282 34

The purpose of this study was to investigate whether dietary phytase is involved in the hydrolysis of phytate in the stomach and small intestine of humans. The digestibility of phytase-deactivated wheat bran was studied on eight occasions and untreated wheat bran on two occasions in healthy ileostomates. Five subjects were studied for two 4-d periods and one subject on two occasions for two 4-d periods while fed a constant low fiber diet. The low fiber diet was supplemented with 16 g/d wheat bran in the second period. Three other subjects fed a low fiber diet were studied for 10 consecutive days, bran being added to the diet on d 5, 6 and 7. Inositol hexaphosphate and its degradation products were analyzed with a recently developed HPLC method. On average, 95% of the ingested phytate from phytase-deactivated wheat bran and 40% of the ingested phytate from untreated wheat bran were recovered in ileostomy contents. These results differ from those of a previous analysis using an iron precipitation method. Mucosal phytase and alakaline phosphatase, if present in the human small intestine, do not seem to play a significant role in phytate digestion in humans, whereas the dietary phytase may be an important factor for phytate hydrolysis. Iron precipitation methods are not adequate for determinations of phytate digestion.
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PMID:Effect of dietary phytase on the digestion of phytate in the stomach and small intestine of humans. 283 90


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