title: Replacement P212H altered the pH-temperature profile of phytase from Aspergillus niger NII 08121.
abstract: Microbial phytase, a widely used animal feed enzyme, needs to be active and stable in the acidic milieu for better performance in the monogastric gut. Aspergillus niger phytases exhibit an activity dip in the pH range from 3.0 to 3.5. Replacement of amino acids, which changed the pKa of catalytic residues H82 and D362, resulted in alteration of the pH profile of a thermostable phytase from A. niger NII 08121. Substitution P212H in the protein loop at 14 Å distance to the active site amended the pH optimum from 2.5 to pH 3.2 nevertheless with a decrease in thermostability than the wild enzyme. This study described the utility of amino acid replacements based on pKa shifts of catalytic acid/base to modulate the pH profile of phytases.
authors.affiliation: Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695 019, India, ushusbt@gmail.com.
authors.forename: Mrudula Vasudevan
authors.initials: MV
authors.lastname: Ushasree
authors.forename: Jalaja
authors.initials: J
authors.lastname: Vidya
authors.forename: Ashok
authors.initials: A
authors.lastname: Pandey
mesh_terms: D010832:6-Phytase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D019943:Amino Acid Substitution; D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017434:Protein Structure, Tertiary; D013696:Temperature
chemical_list: D005656:Fungal Proteins; D010832:6-Phytase