Temperature- and pressure-induced unfolding of α-chymotrypsin

The temperature and pressure dependence on the secondary structure of alpha-chymotrypsin was studied by FT-IR spectroscopy. The temperature dependence of the secondary structures of alpha-chymotrypsin indicates that the temperature-induced unfolding of alpha-chymotrypsin sets in at 41degreesC and pD 7.0 at ambient pressure. Upon unfolding, the content of intermolecular beta-sheet structures increases drastically, whereas that of intramolecular beta-sheets decrease concomitantly. At room temperature (21 degreesC), this protein denatures at similar to4.9 kbar. No aggregation occurs in the pressure-denaturated state. A tentative p-T stability diagram was obtained on the basis of pressure dependent FT-IR measurements at different temperatures.