title: Immobilization of polyphenol oxidase onto mesoporous activated carbons -- isotherm and kinetic studies.
abstract: Investigations were carried out in batch modes for studying the immobilization behavior of polyphenol oxidase (PPO) on two different mesoporous activated carbon matrices, MAC400 and MAC200. The PPO was immobilized onto MAC400 and MAC200 at various enzyme activities 5 x 10(4), 10 x 10(4), 20 x 10(4), 30 x 10(4)Ul(-1), at pH 5-8, and at temperature ranging from 10 to 40 degrees C. The intensity of immobilization of PPO increased with increase in temperature and initial activities, while it decreased with increase in pH. Immobilization onto MAC400 followed the Langmuir model while Langmuir and Freundlich models could fit MAC200 data. Non-linear pseudo first order, pseudo second order and intraparticle diffusion models were evaluated to understand the mechanism of immobilization. The free and immobilized enzyme kinetic parameters (K(m) and V(max)) were determined by Michaelis-Menten enzyme kinetics. The K(m) values for free enzyme, PPO immobilized in MAC400 and in MAC200 were 0.49, 0.41 and 0.65 mM, respectively. The immobilization of PPO in carbon matrices was confirmed using FT-IR spectroscopy and scanning electron microscopy.
authors.affiliation: Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai 600 020, India. jklsac14@yahoo.ca.in
authors.forename: L John
authors.initials: LJ
authors.lastname: Kennedy
authors.forename: P K
authors.initials: PK
authors.lastname: Selvi
authors.forename: Aruna
authors.initials: A
authors.lastname: Padmanabhan
authors.forename: K N
authors.initials: KN
authors.lastname: Hema
authors.forename: G
authors.initials: G
authors.lastname: Sekaran
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000378:metabolism*; D004156:Catechol Oxidase / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
chemical_list: D004800:Enzymes, Immobilized; D002244:Carbon; D004156:Catechol Oxidase