Tm pH7.0


Melting Temperature (Tm)

°C (Celsius)

Circular Dichroism (CD)

0.1 M sodium cacodylate–HCl (pH 7.0)


4 μM

222.6 nm

Thermal unfolding transitions of 4 μM protein in 0.1 M sodium cacodylate–HCl (pH 7.0) and different concentra- tions of NaCl were followed by circular dichroism at 222.6 nm with a 1 nm bandwidth in 10 mm cells using a Jasco J-600A spectropolarimeter equipped with a PTC-348 WI Peltier device. The data were analyzed according to a two-state model using non-linear regression and the program Grafit (Erithacus Software, Staines, UK). The heat capacity change ΔCp was held constant at 4000 J mol− 1 K− 1. The reversibility of thermal unfolding was examined by heating protein samples for 5 min at a temperature that was 10 °C above its Tm value, followed by rapid cooling to 20 °C. The subsequent thermal unfolding transitions were identical with those obtained for a sample without pre-heating.