Abstract: Ultrasonic wave (UW) and ultra-high pressure (UHP) were used for the treatment of lipoxygenase (LOX) from silver carp muscle. Our present work was undertaken to evaluate the effects of UW and UHP treatment on the conformation and enzyme activity of LOX using circular dichroism and fluorescence spectroscopy. The results showed that as the UW power and irradiation time increased, the contents of α-helix and β-sheet in LOX decreased and fluorescence intensity increased, indicating that the secondary and tertiary structures of LOX were greatly changed, leading to a gradual reduction in LOX activity. The optimal UW conditions were 300 W and 3 h, resulting in a decrease in LOX activity of 66.07% when compared with the untreated sample. Moreover, as the UHP processing pressure and time increased, the contents of α-helix and β-sheet decreased and fluorescence intensity steeply declined, suggesting that the secondary and tertiary structures of LOX were greatly changed and consequently LOX activity rapidly dropped. Under the optimum UHP conditions of 300 MPa and 20 min, LOX activity was decreased by 93.10% when compared with the untreated sample.

Key words: silver carp muscle lipoxygenase, ultrasonic wave, ultra high pressure, enzyme activity, conformation