Effects Of Ultra-high Pressure And PH On The Activity,the Secondary And Tertiary Structure Of Spore's Cortex Lyase

The juice can be preserved for a long time after being treated by ultra-high pressure.The spores in the juice will not germinate and grow and cause juice to be spoiled.The cortical lyase is a key enzyme for spore germination.It is presumed that the spore cortex lyase CwlJ is under the condition of ultra-high pressure and acid treatment.In order to confirm this hypothesis,the spore cortex lyase CwlJ extracted from Bacillus subtilis spores was used as the target enzyme protein,respectively,using Fourier transform infrared spectroscopy,circular dichroism spectroscopy and fluorescence spectroscopy.The method was applied to detect the correlation between pH,ultra-high pressure,pH and ultra-high pressure treatment on the structure and vigor of spore cortex lyase CwlJ.The specific research contents and main conclusions are as follows:(1)The effects of different pH treatment conditions on the activity of spore cortex lyase CwlJ were studied.The second and third order structures of spore cortex lyase CwlJ were analyzed by Fourier transform infrared spectroscopy,circular dichroism spectroscopy and fluorescence spectroscopy.Its relationship with the vitality of the enzyme.Through research,it was found that different pH treatments changed the vigor,secondary structure and tertiary structure of the spore cortex lyase CwlJ.The activity of the cortical lyase CwlJ was positively correlated with the structure.The more stable the structure,the stronger the vigor.When pH=3 and 5,the activity of cortical lyase CwlJ is high.When pH=9,the activity of cortical lyase CwlJ is the lowest.It can be speculated that the inhibitory effect of acid on spore germination is not because it inhibits cortical lyase CwlJ.Vitality,which demonstrates that acidic pH inhibits spore germination regardless of its effect on cortical lyase CwlJ activity.(2)The effects of different pressure treatment conditions on the activity of spore cortex lyase CwlJ were studied.The second and third order structures of spore cortex lyase CwlJ were analyzed by Fourier transform infrared spectroscopy,circular dichroism spectroscopy and fluorescence spectroscopy.Its relationship with the vitality of the enzyme.Through research,it was found that ultra-high pressure treatment changed the vigor,secondary structure and tertiary structure of the spore cortex lyase CwlJ.When the treatment time was 10 min,the cortical lyase CwlJ had the strongest vigor at 600 MPa and the structure was the most stable.At 100?500 MPa,with the increase of pressure,the activity gradually increases and the structure becomes more and more stable.When the treatment time is extended to 25 min,the cortical lyase CwlJ has the strongest activity at 100 MPa and the structure is the most stable,at 200-600.Under the condition of MPa,the activity gradually increases with the increase of pressure,but the increase is not obvious,and the structure is more and more stable.It indicated that ultrahigh pressure treatment had a significant effect on the viability and structure of cortical lyase CwlJ.(3)The effects of different pH combined pressure treatment conditions on the activity of spore cortex lyase CwlJ were studied.Fourier transform infrared spectroscopy,circular dichroism spectroscopy and fluorescence spectroscopy were used to analyze the second and third grades of spore cortex lyase CwlJ.Structure and its relationship to the activity of the enzyme.The enzyme activities and structures of the spore cortex lyase CwlJ were studied under different treatment pressures(100 MPa,600 MPa),treatment time(10 min,25 min)and pH(pH=3,5,7,9,11).Influence,the study found that with the increase of pH value,the enzyme activity is continuously decreasing,the activity of cortical lyase CwlJ is positively correlated with the secondary structure,the more stable the secondary structure,the stronger the vigor,and the third-order structure is not positive,relationship.It indicated that the low pH value combined with ultra-high pressure treatment conditions can activate the activity of spore cortex lyase CwlJ.The lower the pH,the higher the pressure,the stronger the activity of cortical lyase CwlJ and the more stable the structure,indicating the spore under the treatment condition of ultra-high pressure combined with acid.The reason for the inhibition of germination was independent of the effect of the viability of the spore cortex lyase CwlJ.This study strengthens the theoretical basis of the application of ultra-high pressure sterilization technology in the processing of juice-based acidic foods,and is conducive to the further promotion and application of ultra-high pressure technology.