Purification, characterization, and cloning of a novel phytase with low pH optimum and strong proteolysis resistance from Aspergillus ficuum NTG-23.
A novel phytase was isolated from Aspergillus ficuum NTG-23 with a procedure involving ion-exchange chromatography on DEAE-cellulose, CM-cellulose and FPLC-gel filtration on Superdex 75. The protein exhibited a molecular mass of 65.5kDa in gel filtration and SDS-PAGE. It possessed an optimal pH of 1.3 and an optimal temperature of 67 degrees C, and manifested a K(m) of 0.295mM and a V(max) of 55.9nmol (phosphate)/min. Phytase activity was not significantly affected by metal ions such as Ca(2+), Mg(2+), Mn(2+), Zn(2+), but was slightly stimulated in the presence of EDTA. The phytase was stable at 60 degrees C with no obvious loss of activity upon its incubation at 70 degrees C for 20min. The enzyme exhibited a broad substrate selectivity and showed strong resistance toward pepsin and trypsin. The unique properties suggest that the phytase has the potential to be useful as an animal feed supplement.
Zhang
G Q
GQ
State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Dong
X F
XF
Wang
Z H
ZH
Zhang
Q
Q
Wang
H X
HX
Tong
J M
JM
D010832:6-Phytase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D001230:Aspergillus / Q000201:enzymology*; D001483:Base Sequence; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D017931:DNA Primers; D010832:6-Phytase