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The question of whether lipases can be activated by adsorption onto an interface in organic solvents was addressed using Rhizomucor miehei lipase as a model. In aqueous solution, this enzyme was shown t o undergo a marked interfacial activation. However, lipase (either Iyophilized or precipitated from water with acetone) suspended in ethanol or 2-(2-ethoxyethoxy)ethanol containing triolein exhibited no jump in catalytic activity when the concentration of triolein exceeded its solubility in these solvents, thereby resulting in formation of an interface. To test whether the lack of interfacial activation was due to the insolubility of the enzyme in organic media, lipase was covalently modified with poly(ethy1ene glycol). The modified lipase, although soluble in nonaqueous media, was still unable t o undergo interfacial activation, regardless of the hydrophobicity of the interface. This inability was found t o becaused by the absence of adsorption of lipase onto interfaces in organic solvents, presumably because of the absence of the hydrophobic effect (the driving force of lipase adsorption onto hydrophobic interfaces in water) in such media. The uncovered lack of interfacial adsorption and activation suggests that the short a-helical "lid" covering the active center of the lipase remains predominantly closed in nonaqueous media, thus contributing t o diminished enzymatic activity.

Highly cross-linked azlactone functional supports were prepared by dispersion polymerization of 2-vinyl-4,4-dimethylazlactone (VDM), 2-hydroxyethyl methacrylate (HEMA), and trimethylolpropane trimethacrylate (TMPTMA). The supports were recovered in high yield and possessed high surface areas. Individual particles, which ranged from 10 to 300 µm in diameter, were irregularly shaped and comprised of filamentous strands. Support polarity was tailored through increases in the HEMA level in the polymer formulations and was quantified by a lipophilicity index derived from solvent partition data collected on the constituent monomers. Support reactivity, as determined by azlactone aminolysis and measured by IR, was found to increase linearly with increasing support polarity. This effect was shown to be independent of the support cross-link density.

The angular triquinane sesquiterpene (-)-silphiperfol-6-ene (1) has been synthesized in efficient fashion from (7?)-(+)-pulegone. Assignment of absolute stereochemistry to one of these architecturally unusual molecules is thereby made possible for the first time. The pyridine chlorochromate oxidation of 1 to (-)-5-oxosilphiperfol-6-ene (2) has previously been reported. As a result, the present work also constitutes a formal total preparation of the correct enantiomer of 2.Silphiperfol-6-ene (1), an architecturally unusual tricyclic sesquiterpene, was isolated in 1980 from the roots of Silphium perfoliatum? Shortly thereafter, the related ketone 2 was characterized as a constituent of the stems of Espeletiopsis quacharaca

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