ELECTROPHORETIC AND SPECTRAL CHARACTERIZATION OF WILD-TYPE AND MUTANTADENOVIRUS PROTEASE

The P137L mutation in the adenovirus type 2 protease results in a temp erature sensitive protein-trafficking phenotype expressed during infec tion but not in vitro. Homology-derived secondary structure prediction placed the mutation within an externally disposed loop. Circular dich roism and urea gradient gel electrophoresis suggested that, unlike oth er thiol proteases, the Ad2 protease is comprised of a single conforma tional domain. The -0.32-kcal difference in the free energy of folding and the temperature-independent CD spectra of the mutant and wild typ e enzymes point to a very subtle structural change as the cause of the in vivo phenotype.