The effect of pulsed electric fields on the inactivation and structure of lysozyme

The effect of pulsed electric fields (PEF) on the activity and structure of lysozyme selected as a model enzyme was investigated. The inactivation of lysozyme in phosphate buffer was a function of electric field strength, treatment time, electrical conductivity, and enzyme concentration. No significant (p>0.05) change in the activity of PEF-treated lysozyme was found after storage for 12, 24 and 48h at 4°C. The effect of PEF on tertiary structure of lysozyme was demonstrated by second-derivative UV spectra and intrinsic fluorescence. The results indicated that the unfolding of tertiary structure was induced by PEF treatment at 35kV/cm for 1200μs, and more tyrosine residues were buried inside the protein after PEF treatment, accompanied by the exposure of more tryptophan residues. CD spectra suggested that the inactivation of lysozyme by PEF was closely related to the loss of α-helix of secondary structure.