Enzyme Stabilization by Virus-Like Particles.

The properties of enzymes packaged within the coat protein shell of virus-like particles (VLPs) were studied to provide a comprehensive assessment of such factors. Such entrainment did not seem to perturb enzyme function, but it did significantly enhance enzyme stability against several denaturing stimuli such as heat, organic solvents, and chaotropic agents. This improvement in performance was found to be general and independent of the number of independent subunits required and of the number of catalytically active enzymes packaged. Packaged enzymes were found by measurements of intrinsic tryptophan fluorescence to retain some of their native folded structure even longer than their catalytic activity, suggesting that protein folding is a significant component of the observed catalytic benefits. While we are unable to distinguish between kinetic and thermodynamic effects - including inhibition of enzyme unfolding, acceleration of refolding, and biasing of folding equilibria - VLP packaging appears to represent a useful general strategy for the stabilization of enzymes that operate on diffusible substrates and products.

Application of vinylogous carbamates and vinylogous aminonitriles to the regiospecific synthesis of uniquely functionalized pyrroles and quinolones.

Pyrroles and quinolones represent core structures, which are routinely found in both natural and synthetic bioactive substances. Consequently, the development of efficient and regiospecific methods for the preparation of such heterocycles with unique functionality is of some importance. We describe herein the regiospecific synthesis of 1,2,3,4-tetrasubstituted pyrroles containing polar substituents and such products are prepared from vinylogous carbamates and vinylogous aminonitriles. We also describe the regiospecific synthesis of 3-aryl containing 1,3,6trisubstituted quinolones from vinylogous carbamates. The use of an amine exchange reaction to prepare precursors for the pyrrole and quinolone forming cyclizations represents a key factor in the strategy.