The heat- and pressure-induced unfolding of the glycosyl-ated and unglycosylated forms of mature carboxypeptidase Y and the precursor procarboxypeptidase Y were analysed by differential scanning calorimetry and/or by their intrinsic fluorescence in the temperature range of 20–75 Corthe pressure range of –700 MPa. Under all conditions, the precursor form showed a clear two-state transition from a folded to an unfolded state, regardless of the presence of the carbohydrate moiety.