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)

In our previous study, it was determined that phytase produced by Aspergillus oryzae plays an important role in supplying phosphate to yeast in the process of making sake. During koji making, two types of phytase (Phy-I and Phy-II) are produced. The purified phytases have high thermal and pH stability, in comparison to phytase purified from a submerged culture (ACP-II). In the present study, Phy-I and Phy-II retained their activities for 45 h. The NH2-terminal sequence of Phy-1, which is eight amino acids in length, was identical to that of ACP-II, but the molecular weights of these two forms, as estimated by SDS-PAGE, were quite different from each other (Phy-I, 120 kDa; ACP-II, 58 kDa). From the NH2-terminal amino acid sequence analysis of the predominant phytase (Phy-II), a molecular weight of 116 kDa was expected to reflect a new type of phytase produced only in koji culture. The substrate specificity of Phy-II was sufficiently broad that it hydrolyzed not only phytic acid and p-nitro phenyl phosphate, but also glucose 6-phosphate and glycerol 1-phosphate. In the process of making koji, Phy-I was produced at an early stage, followed by Phy-II; with both phytases being thought to function to hydrolyze phytic acid cooperatively.
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PMID:Production of two types of phytase from Aspergillus oryzae during industrial koji making. 1623 40

A fungus producing high levels of phytase was isolated from air and identified as Cladosporium sp. The phytase production was stimulated by phytate in the medium used. The maximum production of phytase (108 U/ml) occurred in a medium containing 1.0 g of phytate per 100 ml. The phytase was purified to electrophoretic homogeneity by ion-exchange chromatography and gel filtration. Based on SDS-PAGE analysis, the molecular weight of the purified phytase was calculated to be approximately 32.6 kDa, and the narrow protein band indicated that this phytase is not glycosylated. The phytase has an optimum pH of 3.5, and an optimum temperature of 40 degrees C. The phytase activity was stimulated by 2-mercaptoethanol and dithiothreitol, and inhibited by Ba2+, Pb2+, iodoacetate, p-chloromercuribenzoate and phenylmethylsulfonyl fluoride. The phytase displayed high affinity for phytate and the Km was 15.2+/-3.1 microM. NMR analyses (1D and 2D) indicated that the end hydrolysis product of phytate was myo-inositol 1,2,5-triphosphate.
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PMID:Purification and properties of a low-molecular-weight phytase from Cladosporium sp. FP-1. 1623 25

Phytase (myo-inositol-1,2,3,4,5,6-hexakisphosphate phosphohydrolase, EC 3.1.3.26) catalyses the stepwise hydrolysis of phytic acid (myo-inositol hexakisphosphate). Phytases are of great commercial importance due to their usage as supplement of food and animal feed, which can cater to nutrition demands and alleviate environmental problems, has been approved by many countries. Although acid phytases have been extensively studied, information regarding the phytases from Citrobacter is limited. In the work presented, a phytase was separated from Citrobacter freundii. After steps of electrophoretic homogeneity by successive ammonium sulfate between 60% and 80% saturation precipitation, DEAE-Sepharose ion-exchange chromatography and gel filtration through Superdex HR 10/30, final gel elution resulted in a 41.3-fold purification and yield of 9.3%. Gel elution is an effective method to purify the protein which contaminated with a few other proteins. The purified preparations were used in subsequent characterization studies. Based on SDS-PAGE analysis, the molecular weight of the purified phytase was calculated to be approximately 45.0kDa in monomeric form. The pure enzyme has an optimum pH of 4.0 to approximately 4.5. It was found stable between pH5.0 to approximately 7.0, about 90% of the enzyme activity was retained at 37 degrees C for 60min. The phytase has an optimum temperature of 40 degrees C which was lower than that of other phytases from Aspergillus or E. coli (average 50 to approximately 60 degrees C) and was close to the temperature of gastrointestinal tract in animals (37 to approximately 40 degrees C). Thus the enzyme is a promising candidate for animal feed applications. Activity of the purified phytase was influenced by changing the reaction temperature. Data showed that the enzyme retained its activity over a long period when stored at 4 degrees C, whereas thermal inactivation studies indicated that the enzyme lost 100% activity after treatment at 60 degrees C for 4min. The Km values of the phytase for dodecasodium phytate at 37 degrees C was 0.85nmol/L with a Vmax 0.53IU/(mg x min). Phytase activity was strongly inhibited by SDS, Zn2+ and moderately inhibited by Cu2+, Cr3+, Fe2+ and Fe3+. Activity was not significantly affected by EDTA, K+, Mg2+ and Ca2+. The phytase has excellent resistance to trypsin, but not pepsin. The N-terminal amino acids sequence of the phytase protein was determined as QCAPEGYQLQQVLMM which exhibited about 80% homology to Glucose-1-phosphatases from E. coli, Shigella flexneri and Salmonella, whereas it did not show apparent sequence similarity with any other phytase listed in the databases. Initial characterization of the purified enzyme suggested that it is a potential candidate for use as an animal feed supplement.
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PMID:[Purification and properties of Citrobacter freundii phytase]. 1657 82

In order to improve the fermentation potency of phytase in recombinant host and decrease the production cost, the pichia expression vector pGAPZalpha-A was modified by introduction of an AOX1 promoter from vector pPIC9 and the resulted vector pAOXZalpha is an methanol induced vector. After that, a phytase gene appA-m was cloned into pAOXZalpha to construct the recombinant vector pAOXZalpha-appA-m. The recombinant Pichia pastoris 74#, which already contains one copy of appA-m and its fermentation potency exceeded 7.5 x 10(6) IU/mL, was used as the host strain for the transformation of pAOXZalpha-appA-m. The Pichia pastoris transformants were gained by electroporation. PCR results indicated that the appA-m expression box has integrated into the genome of Pichia pastoris and the original construction of phytase gene has not changed. SDS-PAGE analysis revealed that phytase was overexpressed and secreted into the medium supernatant. Recombinants with high expression level were screened and used for fermentation. In 5L fermentor, the expression level of phytase protein achieved 4 mg/mL and the phytase activity (fermentation potency) exceeded 1.2 x 10(7) IU/mL, which was about 1.6-fold compared with that of the host strain 74#. Moreover, the improved recombinant Pichia pastoris is excellent at expression stability and heredity stability.
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PMID:[Improving phytase expression by increasing the gene copy number of appA-m in Pichia pastoris]. 1689 82

Utilization of the phytase with high specific activity is an effective way to improve the fermentation potency of phytase in recombinant host and decrease the production cost. Up to now, the phytase APPA from Citrobacter braakii exhibits the highest specific activity in the all phytases recorded previously. The gene AppA encoding phytase was modified according to the bias in codon choice of the high expression gene in Pichia pastoris without changing the amino acid sequence and artificially synthesized. The modified gene, AppA ( m) , was inserted into the Pichia pastoris expression vector pPIC9 under the control of AOX1 promoter, and the resulted expression vector pPIC9-AppA ( m) was introduced into the host Pichia pastoris by electroporation. PCR analysis of the recombinant yeast indicated that AppA (m) gene was integrated into the chromosome of Pichia pastoris. The Pichia pastoris recombinants for phytase overexpression were screened by enzyme activity analysis and SDS-PAGE. The recombinant phytase APPA was purified by simple methods, such as dialysis, ultrafiltration and chromatography. After the simple purification, the purity of the recombinant phytase reached to electrophoresis purity, and the recombinant phytase was shown to be glycosylated by Endo-H treatment. The specific activity of the purified recombinant APPA was 3.5 x 10(6) IU/mg of protein. Recombinant phytase APPA showed activity at pH values from 2.0 through 7.0 with the optimum at 4.5. The temperature optimum was 55 degrees C at pH 4.5.The Km value for sodium phytate was 0.165mmol/L with a Vmax of 3.3 x 10(6)IU/mg min. In 5-liter fermentor in fed-batch fermentation, the expression level of phytase in recombinant Pichia pastoris was 3.2mg/mL and the fermentation potency exceeded 1.4 x 10(7) IU/mL, which is the highest level among all of the reported phytase recombinant strains at present.
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PMID:[Overexpression of Citrobacter braakii phytase with high specific activity in Pichia pastoris]. 1730 59

This research amplified the phyA gene with the designed and synthesized primers specific for the phyA gene full-length coding sequence. The phyA gene was from Aspergillus niger F246 by the polymerase chain reaction(PCR), which is selected and identified in our laboratory. After sequncing the coding sequence, it was confirmed that the construction of cloning vector was succeeded. The phyA gene fragment was recovered from the pMD18T-phyA and ligated with prokaryotic expression vector pET30a+ to construct the recombinant expression plasmid pET30a+ -phyA. It was expressed with IPTG induction in E. coli for high efficiency. A new protein band with apparent molecular weight 50 kDa was detected in the lysate of the transformed cell by using SDS-PAGE. The amount of the soluble fusion protein was about 40% of large intestine bacillus soluble protein of transformed cells, estimated by absorbance scanning of SDS-PAGE and protein quantitation. It's phytase activity was eight times over the natural phyase. So this research provides the basis of the study on obtaining large and high active phytase and developmant of the new microbial ecologicalagent.
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PMID:[Cloning of a phyA gene and its over expression in E. coli]. 1733 17

Acid phosphatase activity was detected in peanut (Arachis hypogaea) cotyledons during germination. Four (4) to six (6) days of germination was the meantime corresponding to maximum hydrolytic activity of this enzyme. The understanding of the role of acid phosphatase activity during germination led to purify this enzyme by successive chromatography separations on DEAE-Sepharose CL-6B, Sephacryl S-100 HR and Phenyl-Sepharose HP to apparent homogeneity from germinated peanut cotyledon five days old. This enzyme designated peanut cotyledon acid phosphatase (AP) had native molecular weight of 24 kDa by gel permeation. SDS-PAGE of the purified acid phosphatase resolved a single protein band that migrated to approximately 21.5 kDa. Thus, this acid phosphatase likely functions as a monomer. The enzyme had optimum pH (5.0) and temperature (55 degrees C), and appeared to be stable in the presence of anionic, cationic and non-ionic detergents. Substrate specificity indicated that the purified acid phosphatase hydrolyzed a broad range of phosphorylated substrates. However, natural substrates such as ADP and ATP were the compounds with highest rate of hydrolysis for the enzyme. Moreover, the purified acid phosphatase exhibited phytase activity. These results showed that this enzyme played a peculiar role during germination, notably in reducing the rate of phytic acid, an antinutritional substance contained in peanut seed.
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PMID:Purification, kinetic properties and physicochemical characterization of a novel acid phosphatase (AP) from germinating peanut (Arachis hypogaea) seed. 1772 56

Phytases are enzymes that catalyze liberation of inorganic phosphates from phytate, the major organic phosphorus in soil. Tobacco (Nicotiana tabacum) responds to phosphorus starvation with an increase in extracellular phytase activity. By a three-step purification scheme, a phosphatase with phytase activity was purified 486-fold from tobacco root exudates to a specific activity of 6,028 nkat mg(-1) and an overall yield of 3%. SDS-PAGE revealed a single polypeptide of 64 kDa, thus indicating apparent homogeneity of the final enzyme preparation. Gel filtration chromatography suggested that the enzyme was a ca. 56 kDa monomeric protein. De novo sequencing by tandem mass spectrometry resulted in a tryptic peptide sequence that shares high homology with several plant purple acid phosphatases. The identity of the enzyme was further confirmed by molybdate-inhibition assay and cDNA cloning. The purified enzyme exhibited pH and temperature optima at 5.0-5.5 and 45 degrees C, respectively, and were found to have high affinities for both p-nitrophenyl phosphate (pNPP; K(m)=13.9 microM) and phytate (K(m)=14.7 microM), but a higher kcat for pNPP (2,056 s(-1)) than phytate (908 s(-1)). Although a broad specificity of the enzyme was observed for a range of physiological substrates in soil, maximum activity was achieved using mononucleotides as substrates. We conclude that the phytase activity in tobacco root exudates is exhibited by a purple acid phosphatase and its catalytic properties are pertinent to its role in mobilizing organic P in soil.
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PMID:Phytase activity in tobacco (Nicotiana tabacum) root exudates is exhibited by a purple acid phosphatase. 1789 89

Phytase genephyA2, whose signal peptide encoding sequence and intron sequence had been removed, was modified. The Arg-encoding codons CGG and CAG inphyA2 were mutated into synonymous codon AGA. The modifiedphyA2 was fused behind a-factor signal sequence under the control ofAOX1 promoter in plasmid pPIC9, then introduced into the hostPichia pastoris by electroporation. The results of Southern blotting analysis and Northem blotting analysis demonstrated that thephyA2 gene had integrated into the genome ofP. pastoris and transcribed. The result of SDS-PAGE of the phytase expressed by P.pastoris showed that the modifiedphyA2 had been overexpressed and secreted. The concentration of the phytase expressed by P.pastoris with modifiedphyA2 exceeded 15 000 U/mL, which had a 3 000-fold increase over that of originAspergillus niger 963 and was 37 times higher than that of recombinantP. pastoris with non-modifiedphyA2.
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PMID:RecombinantPichia pastoris overexpressing bioactive phytase. 1842 41

The phyA(m) gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichia pastoris in order to expand the pH profile of phytase and decrease the cost of production. The fusion phytase phyA(m)-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is (25.4+/-0.53) U/ml at the flask scale and (159.1+/-2.92) U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 degrees C and an optimal pH at 5.5~6.0 and its relative activity remains at a relatively high level of above 70% in the range of pH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 degrees C to 95 degrees C for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After deglycosylation by endoglycosidase H (EndoH(f)), the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those of phyCs and phyA(m).
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PMID:Expression, purification and characterization of a phyA(m)-phyCs fusion phytase. 1860 Jul 83


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