Abstract:

In order to examine the impact of ultra high pressure (UHP) on the enzyme activity and conformational change of
papain, infrared spectroscopy and fluorescence spectroscopy were used to analyze structural and specific amino acid changes
in UHP-treated papain. The results showed that compared with untreated sample, UHP treatments at various pressure had
a significant effect on papain activity (P < 0.05). After being treated with 200 MPa, at 37 ℃ for 20 min, the activity of
papain reached the maximum level, indicating a 6.8% increase compared with the untreated one. The infrared spectroscopic
showed that there was a poor relationship between papain activity and conformation. The fluorescence spectroscopic analysis
suggested that the exogenous fluorescence intensity of papain treated with 200 MPa at 37 ℃ for 20 min reached the minimum
level (2 023) at an excitation wavelength of 228 nm. There was an excellent correlation between papain activity and fluorescence
intensity. Therefore, papain activity was negatively related to the exposure degree of hydrophobic amino acids.

Key words: high-pressure technology, papain, enzyme activity, spatial conformation, infrared spectroscopy, fluorescence spectroscopy