kd: Inactivation rate constant

Stability/Folding

Inactivation Rate Constant (kd)

1/(%·min)

Chromatography (HPLC, TLC)

50 mM Tris-HCl

60 °C

7.0

None

None

None

The half-life of protein activity was measured by placing 100 µL of proteins at 60 °C. Samples were removed at different times and then cooled to 22 °C. Second-order thermal deactivation was fitted to:

1/A(t) = 1/A0 + kt

where A(t) is the activity at time t of the heat treatment, A0 is the initial activity before heat treatment, and k is the inactivation rate constant. Half-life (t1/2) at 60 °C was calculated as t1/2 = 1/(100*kd). Retained activity (RA) after time t of heating was calculated as A(t)/A0.