FIG. 2.

Temperature-dependent unfolding and refolding of phytases and pH 2.5 acid phosphatase as determined by CD measurements. (A and B) A. fumigatus phytase. (C and D) A. niger T213 phytase. (E and F) A. niger pH 2.5 acid phosphatase. The individual acid phosphatases were incubated for 20 min at 30°C (——), 50°C (––––), 70°C (······), 80°C (–·–·–), or 90°C (–···–···–). Then either the CD spectra were determined directly at the same temperatures (A, C, and E), or the phosphatases were allowed to renature for 1 h at 30°C, and then the spectra were determined at 30°C (B, D, and F). The isodichroitic point observed for A. fumigatus phytase is indicated by an arrow in panel A. θ, residual molar ellipticity.