Laccase from Rhus vernicifera Stokes oxidized coniferyl alcohol (1) very slowly in acetone-Water (1:1, v/v) in the presence of molecular oxygen. At the reaction time of 144hrs, about 20mol% of pinoresinol (2), 25mol% of dehydrodiconiferyl alcohol (3), and 2mol% of guaiacylglycerol-ß-coniferyl ether (4) were produced, but no dehydrogenative polymer (DHP). Laccases from Coriolus versicolor and Pycnoporus coccineus oxidized the substrate faster than Rhus laccase. At the reaction time of 1.5 hrs, Coriolus iaccase oxidized the substrate, producing all three dimers and a trace amount of DHP, and Pycnoporus laccase producing dimers 2 and 3 but no DHP. At the reaction time of 12hrs, Coriolus laccase oxidized the substrate, producing all three dimers and a small amount of DHP, and Pycnoporus laccase producing only DHP but no dimers. Peroxidase type I and II from horseradish (Armoracia rusticana) oxidized the substrate even faster than the laccases in acetone-water (1:4, v/v) in the presence of hydrogen peroxide, producing DHP predominately at the reaction time of 5 hrs. Tree-laccases may differ from fungal laccases in the oxidation rate and reaction mechanisms. This is probably due to differences in the nature and molecular mass of these glycoproteins, as well as the ligand binding mode of type 2 and type 3 copper sites. During the oxidation by the laccases and peroxidases, the substrate and polymeric products could also undergo biodegradation. The possible role of laccase in biosynthesis of lignin is discussed.

The effectiveness of several basic compounds for testing silica-based stationary phases was reviewed by applying them to recent columns for reversed-phase HPLC. Most octadecylsilylated (C18) stationary phases, prepared as a base-deactivated material from high-purity silica gel with endcapping, provided excellent peak shape and column efficiency for the bases including benzylamine and amitriptyline that once caused problems and were subsequently employed for testing silanol activities. However, a cyclic tertiary amine, dextrometorphan, was eluted as an acceptable peak from only a few columns at neutral pH. Such a more sensitive probe is expected to contribute to further improvement of the stationary phase for reversed-phase HPLC.

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