PRESSURE EFFECTS ON THE STABILITY OF LIPOXYGENASE - FOURIER TRANSFORM-INFRARED SPECTROSCOPY (FT-IR) AND ENZYME-ACTIVITY STUDIES

Fourier transform infrared spectroscopy (FT-IR) studies of lipoxygenas e at pressures of up to 1.2 GPa have shown changes in the amide I' ban d which correlate to structural changes of the enzyme. The shift of th e frequency maximum of the amide I' band at about 600 MPa suggests a c ooperative change in the secondary structure of the protein. Studies o f the changes in band width have shown the structural changes at 600 M Pa to be irreversible. This has been confirmed by studies of enzyme ac tivity after pressure treatment: exposure to 600 MPa for 30 min (40 de grees C) clearly reduced the activity of lipoxygenase. Anodic gel elec trophoresis under non-denaturating conditions revealed a decrease in n ative protein parallel to the activity loss. A pressure-temperature-ph ase diagram for soybean lipoxygenase was established.