title: Catalytic activity of lignin peroxidase and partition of veratryl alcohol in AOT/isooctane/toluene/water reverse micelles.
abstract: The activity of lignin peroxidase (LiP) and the partition of its optimum substrate veratryl alcohol (VA) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/toluene/water reverse micelles were studied in this paper to understand the microheterogeneous effect of the medium on the catalytic properties of LiP hosted in the reverse micelle. Results showed that LiP from Phanerochaete chrysosporium could express its activity in the reverse micelles, but its activity depended, to a great extent, on the composition of the reverse micelles. Optimum activity occurred at a molar ratio of water to AOT (omega0) of 11, a pH value of 3.6, and a volume ratio of isooctane to toluene of 7-9. Under optimum conditions, the half-life of LiP was circa 12 h. The dependence of LiP activity on the volume fraction of water in the medium (theta), at a constant omega0 value of 11, indicated that VA was mainly solubilized in the pseudophase of the reverse micelle. Based on the pseudobiphasic model and the corresponding kinetic method, a linear line can be obtained in a plot of apparent Michaelis constant of VA vs theta, and the partition coefficient of VA between the pseudophase and the organic solvent phase was determined to be 35.8, which was higher than that (22.3) between bulk water and the corresponding mixed organic solvent. H2O2 inhibited LiP at concentrations higher than 80 microM; this concentration value seems to be different from that in aqueous solution (about 3 mM). The differences mentioned above should be ascribed to the microheterogeneity and the interface of the AOT reverse micelle.
authors.affiliation: Key Lab for Colloid and Interface Chemistry of the Education Ministry of China, Shandong University, Jinan, 250100, People's Republic of China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Zhang
authors.forename: Xirong
authors.initials: X
authors.lastname: Huang
authors.forename: Yuezhong
authors.initials: Y
authors.lastname: Li
authors.forename: Yinbo
authors.initials: Y
authors.lastname: Qu
authors.forename: Peiji
authors.initials: P
authors.lastname: Gao
mesh_terms: D001592:Benzyl Alcohols / Q000737:chemistry*; D001709:Biotechnology; D002384:Catalysis; D004143:Dioctyl Sulfosuccinic Acid; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008823:Micelles; D009795:Octanes; D010544:Peroxidases / Q000378:metabolism*; D020075:Phanerochaete / Q000201:enzymology*; D014050:Toluene; D014867:Water
chemical_list: D001592:Benzyl Alcohols; D008823:Micelles; D009795:Octanes; D014867:Water; D004143:Dioctyl Sulfosuccinic Acid; D014050:Toluene; D006861:Hydrogen Peroxide; D010544:Peroxidases; C042858:lignin peroxidase; C042197:veratryl alcohol; C045798:2,2,4-trimethylpentane