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)

Phytase was purified from Aspergillus niger culture fluid by molecular sieve filtration on Sephadex G-200, followed by thermal inactivation of acid phosphatase and CM-cellulose chromatography. The 12-fold purified enzyme had two pH optima at 2.7 and 5.5 and was characterized by high thermal stability in alkaline environment and broad substrate specificity. The Michaelis constant of phytase relative to myo-inositol hexaphosphate sodium salt is 4.8 X 10(-4) M and activation energy 9,217 cal/mole. The molecular weight of the enzyme is estimated at 200,000.
 ...
PMID:Some properties of partially purified phytase from Aspergillus niger. 7 23

The ability of eight strains of Aspergillus niger to produce citric acid by the solid surface method were found to correlate with their capabilities to synthesize intracellular enzymes which degrade phytates (phytase and acid phosphatase). Another high correlation was observed between phytase and acid phosphatase activities bound to the cell walls of mycelia.
 ...
PMID:Relationship between citric acid production and accumulation of phytate-degrading enzymes in Aspergillus niger mycelia. 128 48

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.
 ...
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.
 ...
PMID:Purification and characterization of acid phosphatase from cotyledons of germinating soybean seeds. 282 34

The effects of dietary phosphorus and sulphaguanidine levels, and sex differences on: (a) phytate digestibility, (b) calcium and P utilization, (c) the activities of alkaline phosphatase (EC 3.1.3.1), alkaline phytase (EC 3.1.3.8) and acid phosphatase (EC 3.1.3.2) in the intestinal mucosa of male and female rats were investigated. There was a linear increase in femur ash, Ca and P contents and the maximum force withstood by the fresh femurs as dietary P level was increased from 1.5 to 3.0 to 4.5 g/kg diet. The apparent digestibilities of Ca, P and phytate-P decreased as the level of P in the diet increased. Rats given the diets with 1.5 or 3.0 g P/kg were hypercalciuric and hypophosphaturic compared with rats receiving 4.5 g P/kg diet. The level of Ca retained was similar for all treatments. The level of P retained increased as the dietary P level increased. This suggests that P deprivation was a result of inadequate amounts of P retained and not due to the absorption of inositol phosphates formed during the enzymic hydrolysis of phytate. The addition of sulphaguanidine increased phytate digestibility without changing the activities of acid and alkaline phosphatase or alkaline phytase of the intestinal mucosa. This suggests that these enzymes did not play a role in the increase in phytate digestibility. However, dietary sulphaguanidine enhanced phytate digestibility, suggesting that alterations in the diet which modify either the composition or metabolism of the gastrointestinal microflora may be beneficial in enhancing the in vivo hydrolysis of phytate. Differences between males and females are reported and discussed.
 ...
PMID:Influence of dietary phosphorus and sulphaguanidine levels on P utilization in rats. 632 99

An in vitro method was developed to predict inorganic P release from maize-soyabean poultry feeds containing supplemental phytase (EC 3.1.3.8), and to quantify the effect of acid phosphatase (EC 3.1.3.2), fungal protease (EC 3.4.23.6) and Aspergillus niger cellulase (EC 3.2.1.4) on phytate dephosphorylation. Pepsin (EC 3.4.23.1) and pancreatin digestion periods were preceded by a 30 min pre-incubation at pH 5.25 to simulate digestion in the crop of poultry. Pancreatin digestion was carried out in dialysis tubing, with a ratio of about 1:25 (v/v) between the digesta and dialysing medium, to simulate gradient absorption from the duodenum. The feed:water ratio was kept within physiological limits and a constant proportion of feed weight to digestive enzymes was maintained. There was a linear response to increasing dosages of phytase up to 1000 phytase units (FTU)/kg feed, and to increasing phosphate concentration in feeds. In vivo validation was performed with growing turkeys (1-3 weeks) fed on diets containing 12 g Ca/kg and 0, 500 or 1000 FTU phytase/kg in a factorial arrangement with 0, 1, 2 or 3 g supplemental phosphate/kg (from KH2PO4). After a simple transformation (variable/in vitro P = f (in vitro P)), amounts of P hydrolysed from feed samples by in vitro digestions correlated with 3-week body-weight gain (R 0.986, P < 0.0001), toe ash (R 0.952, P < 0.0001), feed intake (R 0.994, P < 0.0001) and feed efficiency (R 0.992, P < 0.0001). The dephosphorylating ability of phytase in vitro was significantly enhanced (P < 0.05) by the addition of acid phosphatase. Fungal acid protease and Aspergillus niger cellulase also enhanced the dephosphorylation process in vitro.
 ...
PMID:An in vitro procedure for studying enzymic dephosphorylation of phytate in maize-soyabean feeds for turkey poults. 754 27

Four acid phosphatase (phosphomonoesterase E.C.3.1.3.2) genes were cloned by polymerase chain reaction (PCR). These were pho3, pho5 and pho11 from Saccharomyces cerevisiae and the gene for a phosphate-respressible acid phosphatase from Aspergillus niger. The individual genes were subcloned into an A. oryzae expression vector downstream from a starch-inducible alpha-amylase promoter and the resulting expression constructs were transformed into a mutant strain of A. oryzae, AO7. Southern hybridization analysis confirmed that the acid phosphatase genes had been integrated into the host genome with estimates of integrated copy numbers ranging from 2 to 20 for individual transformants. Northern hybridization analysis of total RNA from individual transformants revealed the presence of a single transcript of the expected size of 1.8 kb. Production of recombinant protein was induced by the addition of 30 g L-1 of soluble starch in the fermentation media. Active acid phosphatases, not present in control cultures, were detected in the supernatant fractions of transformant cultures by acid phosphatase activity staining of non-denaturing polyacrylamide gels. The ability of the recombinant acid phosphatases to hydrolyze phytate was assessed by referenced phytase (myoinositol hexakisphosphate phosphohydrolase E.C. 3.1.3.8) activity assay procedures. A two- to six-fold increase in phytase activity was measured in transformants compared to control, untransformed A. oryzae. Sufficient quantities of A. niger and pho5 recombinant acid phosphatases were generated from large-scale fermentations to assess the efficacy of these enzymes as phytate-degrading enzymes when included in poultry diets.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Molecular cloning, expression and evaluation of phosphohydrolases for phytate-degrading activity. 761 16

An Aspergillus niger (ficuum) genomic DNA lambda EMBL3 library was probed with a 354-bp DNA fragment obtained by polymerase chain reaction of A. niger DNA with oligonucleotides based on partial amino acid sequence of a pH 2.5 optimum acid phosphatase. A clone containing a 1605 bp segment (phyB) encoding the 479 amino acid enzyme was isolated and found to contain four exons. Global alignment revealed 23.5% homology to Aspergillus niger phytase (PhyA); four regions of extensive homology were identified. Some of these regions may contain catalytic sites for phosphatase function.
 ...
PMID:Identification and cloning of a second phytase gene (phyB) from Aspergillus niger (ficuum). 791 10

Three secreted acid phosphatases had previously been characterized from Aspergillus ficuum grown under conditions of limited phosphate. One of these could not be readily separated from AFPhyB, a pH 2.5 optimum acid phosphatase with phytase activity. From extensive protein sequence analysis and subsequent cloning of the gene, we have shown that the AFPhyB protein fraction contains a fourth secreted acid phosphatase (AFPhoA) that has 64% homology to a phosphate-repressible acid phosphatase from Penicillium chrysogenum. Garnier plot analysis revealed that the putative phosphate catalytic domain of AFPhoA at His215Asp216 is similar to those of other acid phosphatases, but that AFPhoA lacks the phosphate-binding motif RHGXRXP of known histidine phosphatases.
 ...
PMID:An acid phosphatase from Aspergillus ficuum has homology to Penicillium chrysogenum PhoA. 794 93

The genes encoding phytase (EC 3.1.3.8) and pH 2.5-optimum acid phosphatase (EC 3.1.3.2) have been cloned and sequenced from Aspergillus niger var. awamori. The translated nucleotide sequences yielded polypeptides of 467 and 479 amino acids (aa) for phytase and acid phosphatase, respectively. The genes were isolated using oligodeoxyribonucleotide probes based on the aa sequences of the purified proteins. Recombinant A. niger var. awamori strains carrying additional copies of the gene sequences demonstrated elevated enzyme activities.
 ...
PMID:The cloning and sequencing of the genes encoding phytase (phy) and pH 2.5-optimum acid phosphatase (aph) from Aspergillus niger var. awamori. 822 94


1 2 3 4 5 6 7 8 9 Next >>