Purification and Characterization of Two Functional Forms of Intracellular Protease PfpI from the Hyperthermophilic Archaeon Pyrococcus furiosus

The hyperthermophilic archaeon Pyrococcus furiosus grows optimally at 100(deg)C by the fermentation of peptides and carbohydrates. From this organism, we have purified to homogeneity an intracellular protease, previously designated PfpI (P. furiosus protease I) (S. B. Halio, I. I. Blumentals, S. A. Short, B. M. Merrill, and R. M. Kelly, J. Bacteriol. 178:2605-2612, 1996). The protease contains a single subunit with a molecular mass of...