ENZYMATIC OXIDATION OF WATER-SOLUBLE CYCLODEXTRIN-POLYNUCLEAR AROMATIC HYDROCARBON INCLUSION COMPLEXES, USING LIGNIN PEROXIDASE

alpha-,beta-,gamma-, and 2-hydroxypropyl-beta-cyclodextrins were capab le of forming water-soluble inclusion complexes with several polynucle ar aromatic hydrocarbons (PAHs). The highest solubilities were noted f or beta-cyclodextrin and 2-hydroxypropyl-beta-cyclodextrin (hp beta CD ). The solubility of PAHs in hp beta CD was enhanced 224-fold and 7,50 0-fold for naphthalene and benzo[a]pyrene, respectively, with other PA Hs yielding values between these limits. The ability of lignin peroxid ase (LiP) to oxidize these cyclodextrin-included substrates was simila r to that previously reported for mixed solvent systems. The enzyme ox idized anthracene, pyrene, and benzo[a]pyrene but not naphthalene, phe nanthrene, chrysene, and benzo[e]pyrene. The lignin peroxidase exhibit ed a preference for oxidizing either anthracene or benzo[a]pyrene when mixed with pyrene. On the basis of fluorescence measurement, anthrace ne and benzo[a]pyrene were easily distinguished by exciting at 250 nm for anthracene and 295 nm for benzo[a]pyrene. Veratryl alcohol severel y inhibited the pyrene assay, with 50% inhibition noted at 0.3 mM whil e veratryl alcohol activated the reactions between LiP and either anth racene or benzo[a]pyrene. Maximal activation was obtained at 1.5 mM ve ratryl alcohol and no inhibitory effect was detected up to 4.0 mM. Und er identical conditions, the rate of reaction with veratryl alcohol (4 .0 mM) was 11- and 14-fold faster for benzo[a]pyrene and anthracene, r espectively, when compared to the assays in the absence of veratryl al cohol.