Unfolding and nanotube formation of ovalbumin induced by pulsed electric field

Abstract It was investigated in this study that the effect of pulsed electric field (PEF) on the structure of ovalbumin with or without adding Ca 2 + ion. Results showed that for the protein solution without Ca 2 + addition, the application of repeating PEF treatment and increasing PEF treatment intensity induced changes of the secondary and tertiary structure. The unfolded fraction of tertiary structure was bigger than that of the secondary structure. More changes in secondary structure of protein solution were observed with Ca 2 + addition. However, a new peak at 215 nm in CD spectrum was observed with synergistic effect of PEF and Ca 2 + ions. This peak was attributed to the increase of β-sheet structure. Transmission Electron Microscopy (TEM) images showed that the protein nanotube generated in protein solution was correspondingly related with the new peak appearance at 215 nm. These results suggested that PEF could be a novel processing technology for preparing protein nanotubes.