Structural information on partially folded forms is important for a deeper understanding of the folding mechanism(s) and the factors affecting protein stabilization. The non-native compact state of equine cytochromecstabil-ized by salts in an acidic environment (pH –), called the A-state, is considered a suitable model for the molten globule of cytochromec,asit possesses a native-likea-helix conformation but a fluctuating tertiary struc-ture.