title: Expression, purification and characterization of a phyA(m)-phyCs fusion phytase.
abstract: 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).
authors.affiliation: College of Life Science, Bioengineering Research Center for Animal Disease Prevention and Control, Sichuan University, Chengdu, China. zoulkcn@hotmail.com
authors.forename: Li-Kou
authors.initials: LK
authors.lastname: Zou
authors.forename: Hong-Ning
authors.initials: HN
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Pan
authors.forename: Guo-Bao
authors.initials: GB
authors.lastname: Tian
authors.forename: Zi-Wen
authors.initials: ZW
authors.lastname: Xie
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Tao
authors.initials: T
authors.lastname: Xie
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Yang
mesh_terms: D010832:6-Phytase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D005285:Fermentation; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010843:Pichia / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000302:isolation & purification
chemical_list: D011993:Recombinant Fusion Proteins; D010832:6-Phytase