title: Structural characterization, catalytic, kinetic and thermodynamic properties of Aspergillus oryzae tannase.
abstract: Tannase (EC.3.1.1.20) from Aspergillus oryzae was purified using ammonium sulphate precipitation (75%), gel filtration chromatography through Sephadex G-100, and G-200. The purified enzyme was monomeric protein with a molecular mass of 106kDa. The activation energy for tannic acid hydrolysis was 32.6kJmol-1and its temperature quotient (Q10) was 1.0. The pKa1and pKa2values of acidic and basic limbs of the active site residues were 4.6 and 6.4. The calculated values of thermodynamic parameters for tannic acid hydrolysis, were as follows: ΔH*=30.02kJmol-1, ΔG*=59.75kJmol-1ΔS*=-95.90Jmol-1K-1, (ΔG*E-S)=3.66kJmol-1and ΔG*E-T-12.61kJmol-1. The pure enzyme exhibited Km, Vmaxand kcatof 4.13mM, 3507Umgprotein-1and 551.4s-1.The calculated half-life time at 40, 45, 50, 55, 60, and 70°C was 955.15, 142.0, 30.28, 17.88, 8.23 and 2.95min, respectively. The thermodynamic parameters for irreversible thermal inactivation at different temperatures (40-70°C) were determined. The enzyme was activated by Ca2+, and Mg2+while Hg2+, Fe2+, and Cu2+strongly inhibited it. Hydrolysis of tannic acid by the pure enzyme indicated that gallic acid was the end-product.
authors.affiliation: Department of chemistry of natural and microbial products, National Research Center, Cairo, Egypt. Electronic address: mabdel_2010@yahoo.com.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Abdel-Naby
authors.affiliation: Botany Department, Faculty of Science, Mansoura University, Mansoura, Egypt.
authors.forename: Arafat Bedier
authors.initials: AB
authors.lastname: El-Tanash
authors.affiliation: Botany Department, Faculty of Science, Mansoura University, Mansoura, Egypt.
authors.forename: Abdel Daium A
authors.initials: AD
authors.lastname: Sherief
mesh_terms: D001236:Aspergillus oryzae / Q000737:chemistry / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002850:Chromatography, Gel; D004795:Enzyme Stability; D005285:Fermentation; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D005707:Gallic Acid / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D013634:Tannins / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005656:Fungal Proteins; D013634:Tannins; D005707:Gallic Acid; D002265:Carboxylic Ester Hydrolases; C022711:tannase
keywords: Tannin degradation; Thermodynamic properties; catalytic properties