Baseline length and automated fitting of denaturation data

To understand relationships between protein sequence and stability, we often compare data from proteins that differ by the substitution of one amino acid. Frequently, an amino acid change causes the cooperative denaturation transitions to shift to lower temperatures, diminishing the signal from the native state. Here we show that apparent stability changes, i.e., the free energy of denaturation, Delta G(D), can also be caused by a deficiency of points in the low temperature end of the transition. In addition, we suggest a method for overcoming this problem.