title: A phytase characterized by relatively high pH tolerance and thermostability from the shiitake mushroom Lentinus edodes.
abstract: A monomeric phytase with a molecular mass of 14 kDa was acquired from fresh fruiting bodies of the shiitake mushroom Lentinus edodes. The isolation procedure involved chromatography on DEAE-cellulose, CM-cellulose, Q-Sepharose, Affi-gel blue gel, and a final fast protein liquid chromatography-gel filtration on Superdex 75. The purified phytase demonstrated the unique N-terminal amino acid sequence DPKRTDQVN, which exhibited no sequence similarity with those of other phytases previously reported. It expressed its maximal activity at pH 5.0 and 37 °C. Phytase activity manifested less than 20% change in activity over the pH range of 3.0-9.0, considerable thermostability with more than 60% residual activity at 70 °C, and about 40% residual activity at 95°C. It displayed a wide substrate specificity on a variety of phosphorylated compounds with the following ranking: ATP > fructose-6-phosphate > AMP > glucose-6-phosphate > ADP > sodium phytate > β -glycerophosphate. The phytase activity was moderately stimulated by Ca(2+), but inhibited by Al(3+), Mn(2+), Zn(2+), and Cu(2+) at a tested concentration of 5 mM.
authors.affiliation: College of Biosciences and Biotechnology, Beijing University of Agriculture, Beijing 102206, China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Zhang
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Tzi-Bun
authors.initials: TB
authors.lastname: Ng
authors.forename: Qing-Jun
authors.initials: QJ
authors.lastname: Chen
authors.forename: He-Xiang
authors.initials: HX
authors.lastname: Wang
mesh_terms: D010832:6-Phytase / Q000737:chemistry* / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D002845:Chromatography; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D020942:Shiitake Mushrooms / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D010832:6-Phytase