Chemical and Physicochemical Properties of Phytase from Aspergillus terreus

Yamamoto, So; Minoda, Yasuji; Yamada, Kôichi

doi:10.1271/bbb1961.36.2097

Cited by 14 publications

(3 citation statements)

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“…This conclusion is consistent with the findings of Ullah and coworkers for fungal and soybean seed phytases (5; for a review see reference 29), of Greiner et al (6,7) for E. coli and Klebsiella terrigena phytases, and of Shimizu (22) for Bacillus subtilis phytase. On the other hand, the phytases of A. terreus, Aspergillus oryzae, Schwanniomyces castellii, and maize roots were reported to be homohexameric, heterotetrameric or dimeric proteins (10,21,23,32). The proposed hexameric structure of A. terreus phytase is particularly surprising, since in our study there was no indication of oligomeric forms of A. terreus phytases isolated from two different strains.…”

Section: Discussioncontrasting

confidence: 66%

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Biophysical Characterization of Fungal Phytases ( myo -Inositol Hexakisphosphate Phosphohydrolases): Molecular Size, Glycosylation Pattern, and Engineering of Proteolytic Resistance

Wyss

Pasamontes

Friedlein³

et al. 1999

Appl Environ Microbiol

177

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Phytases (myo-inositol hexakisphosphate phosphohydrolases) are found naturally in plants and microorganisms, particularly fungi. Interest in these enzymes has been stimulated by the fact that phytase supplements increase the availability of phosphorus in pig and poultry feed and thereby reduce environmental pollution due to excess phosphate excretion in areas where there is intensive livestock production. The wild-type phytases from six different fungi, Aspergillus niger, Aspergillus terreus, Aspergillus fumigatus, Emericella nidulans, Myceliophthora thermophila, andTalaromyces thermophilus, were overexpressed in either filamentous fungi or yeasts and purified, and their biophysical properties were compared with those of a phytase from Escherichia coli. All of the phytases examined are monomeric proteins. WhileE. coli phytase is a nonglycosylated enzyme, the glycosylation patterns of the fungal phytases proved to be highly variable, differing for individual phytases, for a given phytase produced in different expression systems, and for individual batches of a given phytase produced in a particular expression system. Whereas the extents of glycosylation were moderate when the fungal phytases were expressed in filamentous fungi, they were excessive when the phytases were expressed in yeasts. However, the different extents of glycosylation had no effect on the specific activity, the thermostability, or the refolding properties of individual phytases. When expressed in A. niger, several fungal phytases were susceptible to limited proteolysis by proteases present in the culture supernatant. N-terminal sequencing of the fragments revealed that cleavage invariably occurred at exposed loops on the surface of the molecule. Site-directed mutagenesis of A. fumigatus andE. nidulans phytases at the cleavage sites yielded mutants that were considerably more resistant to proteolytic attack. Therefore, engineering of exposed surface loops may be a strategy for improving phytase stability during feed processing and in the digestive tract.

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Section: Discussioncontrasting

confidence: 66%

“…In the four conflicting examples mentioned above, the molecular sizes of the phytases were determined by gel filtration on Sephadex G-200, Sepharose S-200, and Sephacryl HR S300 (10,21,32) or by native PAGE (23). As shown previously (1) and in this study (Fig.…”

Section: Discussionsupporting

confidence: 57%

Biophysical Characterization of Fungal Phytases ( myo -Inositol Hexakisphosphate Phosphohydrolases): Molecular Size, Glycosylation Pattern, and Engineering of Proteolytic Resistance

Wyss

Pasamontes

Friedlein³

et al. 1999

Appl Environ Microbiol

177

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“…As both subunits were expressed differentially during the development of the rat ( Yang et al ., 1991a ), these subunits may represent two different enzymes. The phytate‐degrading enzymes isolated from maize roots ( Hübel & Beck, 1996 ), germinating maize seeds ( Laboure et al ., 1993 ), tomato roots ( Li et al ., 1997b ), soybean seeds ( Hegeman & Grabau, 2001 ) and A. oryzae ( Shimizu, 1993 ) were reported to be homodimeric proteins, whereas a homohexameric structure was proposed for the A. terreus enzyme ( Yamamoto et al ., 1972 ). In other studies there was no indication of an oligomeric structure of the phytate‐degrading enzymes from A. terreus ( Wyss et al ., 1999b ) and soybeans ( Gibson & Ullah, 1988 ).…”

Section: Molecular Massmentioning

confidence: 99%

Molecular and catalytic properties of phytate‐degrading enzymes (phytases)

Konietzny

Greiner

2002

Int J of Food Sci Tech

301

214

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Phytate-degrading enzymes catalyse the step-wise release of phosphate from phytate, the principle storage form of phosphorus in plant seeds and pollen. They are widespread in nature, occurring in plants and micro-organisms, as well as in some animal tissues. Phytate-degrading enzymes have been studied intensively in recent years because of the great interest in such enzymes for reducing phytate content in animal feed and food for human consumption. Phytate-degrading enzymes are also of interest for producing defined breakdown products of phytate for kinetic and physiological studies. Certain myo-inositol phosphates have been proposed to have novel metabolic effects and therefore, the physiological role of different myo-inositol phosphates is presently undergoing extensive research. Generally, phytase behaves like a monomeric enzyme with molecular masses between 40 and 70 kDa. Up to now, two main types of phytate-degrading enzymes have been identified; acid phytate-degrading enzymes with an pH optimum around pH 5 and alkaline phytate-degrading enzymes with an pH optimum around pH 8. Most of the so far described phytate-degrading enzymes belong to the acidic type, and their optimal pH ranges from 4.5 to 6.0. This review summarises the molecular features as well as catalytic properties of phytate-degrading enzymes and also discusses enzymatic phytate degradation.

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