Circular dichroism spectrum of the N-terminal fragment of ClpB (4.24 mg/mL in 50 mM Tris-HCl at pH 7.5, 0.2 M KCl, 20 mM MgCl2, 10% glycerol, 1 mM EDTA, 1 mM DTT) expressed as mean molar residue ellipticity (θ), measured at 25°C (solid line) and 85 °C (broken line).