title: Gene cloning, purification, and characterization of a heat-stable phytase from the fungus Aspergillus fumigatus.
abstract: The finding of heat-stable enzymes or the engineering of moderately thermostable enzymes into more stable ones by random or site-directed mutagenesis has become a main priority of modern biotechnology. We report here for the first time a heat-stable phytase able to withstand temperatures up to 100 degrees C over a period of 20 min, with a loss of only 10% of the initial enzymatic activity. The gene (phyA) encoding this heat-stable enzyme has been cloned from Aspergillus fumigatus and overexpressed in Aspergillus niger. The enzyme showed high activity with 4-nitrophenyl phosphate at a pH range of 3 to 5 and with phytic acid at a pH range of 2.5 to 7.5.
authors.affiliation: Vitamins & Fine Chemicals Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland. luis.pasamontes@roche.com
authors.forename: L
authors.initials: L
authors.lastname: Pasamontes
authors.forename: M
authors.initials: M
authors.lastname: Haiker
authors.forename: M
authors.initials: M
authors.lastname: Wyss
authors.forename: M
authors.initials: M
authors.lastname: Tessier
authors.forename: A P
authors.initials: AP
authors.lastname: van Loon
mesh_terms: D010832:6-Phytase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000235:genetics*; D001234:Aspergillus niger / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D015966:Gene Expression Regulation, Fungal; D015723:Gene Library; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: D004271:DNA, Fungal; D010832:6-Phytase