Abstract:In order to explore the inhibitory mechanism of acidic pH conditions for spore germination, the study investigated effects of different pH treatments on the activity and structure of spore cortical lyase (CwlJ). Using Fourier transform infrared spectroscopy and fluorescence spectroscopy, the relationship between the secondary and tertiary structures of CwlJ and its activity was analyzed. The pH values were set to 3, 5, 7, 9 and 11 in the experiment. The results showed that: 1) CwlJ was activated over time with pH 3 and 5; 2) The activity of CwlJ was closely related to the content of alpha-helix in its secondary structure; when pH value increased from 3 to 5, the content of alpha-helix also increased from 36.15% to 37.29%; when pH increased from 5 to 7, the content of alpha-helix basically unchanged; when pH increased from 7 to 11, the content of alpha-helix decreased; therefore, the enzyme may be activated in the pH range of 3-5; 3) the fluorescence intensity in pH 5 was strongest, the internal protein was fully unfolded, and the spatial structure was more loosely expanded, and the tertiary structure was more stable. In conclusion, the structure of CwlJ was stable and its activity was high in acidic pH conditions, so it was speculated that the inhibition of acidity for spore germination was not due to its inhibition for the activity of cortical lyase.
